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R/E/P => R/E/P Archives => Reason In Audio => Topic started by: jazzius on May 14, 2004, 12:56:30 pm

Title: George....what's the resolution of analog?
Post by: jazzius on May 14, 2004, 12:56:30 pm
George, we hear about the resolution of digital all the time.....24 bits, 44.1, 192.....2.8 million whatevers....

...do you know if anyone has ever worked out the resolution of analog?.....how many bits would it be equivelent to?.....i know this is bit of a strange question, but i'd love to be able to give my customers a smart-arse answer for why analog sounds better then digital...

...cheers.....Darius
Title: Re: George....what's the resolution of analog?
Post by: bblackwood on May 14, 2004, 01:12:18 pm
Well, I'm not GM, but resolution certainly isn't the answer as to why some feel analog sound better. IME, good analog machines have a S/N ratio of about 13 bit and a useable hi-freq limit of about 20kHz or so...
Title: Re: George....what's the resolution of analog?
Post by: Ethan Winer on May 14, 2004, 01:16:40 pm
Darius,

> do you know if anyone has ever worked out the resolution of analog? <

Yes, Arny Krueger from www.pcabx.com has assessed this and commented several times in the audio news groups.

> i'd love to be able to give my customers a smart-arse answer for why analog sounds better then digital <

Uh oh, then I'm afraid you won't like Arny's results. Cool

In any way you care to measure, even a $25 SoundBlaster sound card beats pretty much any analog tape recorder.

--Ethan
Title: Re: George....what's the resolution of analog?
Post by: malice on May 14, 2004, 01:44:01 pm
bblackwood wrote on Fri, 14 May 2004 19:12

Well, I'm not GM, but resolution certainly isn't the answer as to why some feel analog sound better. IME, good analog machines have a S/N ratio of about 13 bit and a useable hi-freq limit of about 20kHz or so...


Sometimes the bandwith is less than that (+/- 3db of course)

malice
Title: Re: George....what's the resolution of analog?
Post by: jazzius on May 14, 2004, 02:38:27 pm
why does it sound better then?

Surely analog works at a higher resolution then digital?....electrons, atoms, eeeerrrrrr.....quarks?! (yeah, i don't actually know what the hell i'm talking about!)
Title: Re: George....what's the resolution of analog?
Post by: Loco on May 14, 2004, 03:17:06 pm
jazzius wrote on Fri, 14 May 2004 14:38

why does it sound better then?


It's not that it's better. It's just easier to get more musical results.

Providing that you are working with a good piece of hardware, of course.
Title: Re: George....what's the resolution of analog?
Post by: jazzius on May 14, 2004, 03:22:40 pm
why why why?
Title: Re: George....what's the resolution of analog?
Post by: bblackwood on May 14, 2004, 03:32:27 pm
Tape saturation (essentially freq-dependant compression).
Title: Re: George....what's the resolution of analog?
Post by: ted nightshade on May 14, 2004, 03:41:51 pm
From what I understand, digital has no dimension called "resolution". There are sampling rates and wordlengths, but those are not "resolution". Nika has talked to me about this a bit, and my own experiences seem to corroborate it. There's no analogy between pixels in a digital picture and digital sound- when it's converted back to analog, it's continuous.

When you say analog, it seems everyone is assuming you mean analog tape- there are in fact many analog tape machines with frequency response well up above 20kHz, even up to 30 kHz. That's not really unusual. There is a noise floor that is rather high compared to digital, but infinitely more pleasant, and even musically useful.

Now if you are talking about analog in general, not just tape, the limits are pretty extreme- response up to 60hz and beyond happens, and down to 1 or 2 hz. Noise floors can be very, very low, but almost always higher than digital. Good thing the analog noise is there to mask the digital noise in most cases- the digital noise is pretty nasty.

There's a lot of stuff called digital out there, and a lot of stuff called analog. That by itself doesn't tell you much.

Title: Re: George....what's the resolution of analog?
Post by: jazzius on May 14, 2004, 03:53:59 pm
sorry...to clarify.....real tape compared to plugin tape simulation......same thing for comps, EQ's, FX, whatever....

Title: Re: George....what's the resolution of analog?
Post by: Nika Aldrich on May 14, 2004, 04:05:36 pm
jazzius wrote on Fri, 14 May 2004 19:38

why does it sound better then?

Surely analog works at a higher resolution then digital?....electrons, atoms, eeeerrrrrr.....quarks?! (yeah, i don't actually know what the hell i'm talking about!)


"Better" is a subjective term.

Some people may like analog equipment for some projects because the way that analog systems are implemented add noise and distortion in pleasing ways.  Some people like digital equipment because good digital systems do not add that distortion.

Clearly, for poorly designed analog or poorly designed digital systems the performance degrades, and digital systems, when poorly designed, generally add distortion that is very "non-musical."  Therefore, many people like analog equipment over mediocre digital equipment, and some people also like good analog equipment over good digital equipment just because they like the more "euphonic" noise and distortion.

Nika.
Title: Re: George....what's the resolution of analog?
Post by: ted nightshade on May 14, 2004, 04:14:27 pm
It's true, implementation is everything, and it's very difficult to do, analog or digital! Kudos to those who do it well.
Title: Re: George....what's the resolution of analog?
Post by: raw-tracks on May 14, 2004, 04:16:03 pm
I could be way off base here, but shouldn't the correct answer be that analog recording has INFINITE resolution. Here is the way I see it:

In a digital system, the sound is stored as samples. Each sample is basically a representation or picture of the audio at that given time. You have the sample rate, which is how many times a second a picture is taken. You also have the bit depth, which represents how many ones and zeros we have to take that picture with. The way I have always understood it, was that the bit depth is the resolution. Therefore, you can have 16 bit resolution, 20 bit, 24 bit, etc. At any given bit depth, the chances of that picture being a perfect representation of the actual audio that is taking place, are next to none. In other words, the system will have to decide how to represent a value that is in between the numbers it is given to work with. I guess this also applies to what is happening in between samples as well.

In an analog system, it is not taking snapshot of the audio. It is continuously representing what is happening. Therefore, it is my belief that analog resolution is infinite.

Title: Re: George....what's the resolution of analog?
Post by: malice on May 14, 2004, 04:34:17 pm
raw-tracks wrote on Fri, 14 May 2004 22:16

I could be way off base here, but shouldn't the correct answer be that analog recording has INFINITE resolution. Here is the way I see it:




Unfortunately it has not infinite resolution...

Unless I don't understand physics right

those quanta you know ...

well, even if they are very very small

Wink

malice

Title: Re: George....what's the resolution of analog?
Post by: sfdennis on May 14, 2004, 04:35:43 pm
I'm surprised the thread got this far without anyone mentioning this:

Digital Word Length <=> Analog Noise Floor
Digital Sample Rate <=> Analog Bandwidth

So for example, in an ideal converter system at 96kHz would correspond with an analog bandwidth of 0-48kHz. A digital word length of 24 bits would correspond with an analog noise floor of about -132dBFS, notwithstanding dither.

The correspondences are not perfect for many reasons, and you have to take some care in applying them, but I always start with these. Ignoring distortion for a moment, all real instruments are bandwidth limited and have a non-zero noise floor.

-Dennis
Title: Re: George....what's the resolution of analog?
Post by: Nika Aldrich on May 14, 2004, 04:39:51 pm
raw-tracks wrote on Fri, 14 May 2004 21:16

I could be way off base here, but shouldn't the correct answer be that analog recording has INFINITE resolution.


Essentially, no.

The accuracy of an system has do with the relationship between the original signal and the amount of error imparted on the signal due to the recording/reproduction process.  Digital systems have far less error than pure analog systems.  Ergo, we would feign to say that analog systems have "infinite resolution" if digital systems are constrained.  Thus, the posts above are far more correct.

We would be better to phrase it in terms other than the nebulous term "resolution" and instead by the actual effects on the waveforms.  Digital systems are capable of error signals being pure noise at levels in the audible range of -120dB, complete phase accuracy for audible range signals, and distortion levels below the noise floor.

Analog systems have a tough time getting the distortion and noise levels below -80dB of peak signal, incur various phase distortions in the audible range, and have distortion that is audibly apparent as opposed to below the noisefloor.

For these reasons, digital audio is capable of far more accuracy than analog audio.  I would probably keep it in these terms and avoid the term "resolution."

Nika.
Title: Re: George....what's the resolution of analog?
Post by: david gregORIO on May 14, 2004, 04:54:31 pm
From Mirriam-Webster online...
Resolution (noun)
1 : the act or process of reducing to simpler form: as a : the act of analyzing a complex notion into simpler ones b : the act of answering : SOLVING c : the act of determining

Digitization by nature depends on reducing a signal (or any information) to a form that a computer can process and store.

Analog Tape recording by nature requires that you add a bias signal which is the opposite of reducing the signal to a simpler form.

so, the answer is zero!.... or maybe.... infinity!

damn, I dunno what I'm talking about, maybe you should just ask George.



Title: Re: George....what's the resolution of analog?
Post by: raw-tracks on May 14, 2004, 04:56:48 pm
By no means was I implying that analog is more accurate. As Nika pointed out, it is the term "resolution" that compelled me to post.
Title: Re: George....what's the resolution of analog?
Post by: 12345 on May 14, 2004, 10:13:33 pm
Pretty straightforward answer.  The threshold of human hearing is in the 24-bit to 27-bit range (depending on the trained ears of the listener).  A 28-bit system (which equals 2 to the 28th power which equals 268,435,456 or 268,435,456 bitrate or 33554432 byterate) is beyond the range of human detection from all studies I have seen.  In this situation, all audible harmonics from a simple or complex source can be resolved within the ear.  

There is a similar analogue to vision.  The "resolution" of human eyesight is approximately 1400x1400 dots per inch (actually slightly skewed in the vertical direction like 1400x1398 due to the stereoscopy) at the focal length of our eyes, but can go higher for trained eyes.  

It's not rocket science.  Yes, analog has "infinite" resolution (but does it really because it is molecularly constrained to the nth molecule, electron, quark, etc., and are the "production" tape masters produced in a clean-room environment?), but the practical application is that if you attain 28-bit resolution, you are golden.  A 32-bit sound card on a computer refers to processing speed, not the signal path.  

When an analog harmonic takes place, the octave, octave-fifth, 2nd octave, etc. harmonics come into the spectrum until some nth divisor squeaks out, and we love it.  Digital is getting there, but not yet.  I have been "begging" sound processing companies for several years to develop 28-bit processors!  C'mon guys!  We're not that far away!  But even when we get there we'll need some clean, highly-controlled oscillations through our power sources, highly-shielded cables, etc.  Cold fusion, anyone?  

Here's a kicker: we hear in digital (the eardrum excites the cilia in our ears, which translate acoustical vibrations into electron flow within our neurotransmitters).  
The electron flow is represented by a series of moving charges, similar to a binary I/O DVD, CD, etc.  

Regards,
My World (yes, that's my name)
My World Studios
Los Angeles, CA
Title: Re: George....what's the resolution of analog?
Post by: Curve Dominant on May 15, 2004, 04:20:38 am
Quote:

posted by My World:
analog has "infinite" resolution


This is an extremely misleading statement. Analog tape has nothing close to "infinite" representation.

This term "resolution" itself is for the realm of the amature. We really should not be throwing this word around so liberally on a professional audio forum.

Do not confuse "infinite" with "random."

And take note of the noise floor.

The noise floor in analog tape is indeed random (Gaussian). But it is still noise, and you can hear it.

The noise floor in digital is not AS random (Triangular), but it is much lower than in analog tape. Used properly, you cannot hear it.

So you are faced with the difference between truly random noise which you can hear, and somewhat more calculatedly random noise, which you cannot.

In either case, do not be fooled into thinking there is something resembling infiteness. There is no infinity in analog tape. Just because your computer moniter "shows" you the finiteness of digital audio doesn't make it "worse" than the finiteness of analog tape. On the contrary. If your analog tape machine could "show" you all of its anamolies, you would run to digital, pronto.

What this should tell you, is that there are some infinities that are bigger than others. How is that possible? Simple:

Take simple numbers. There are an infinte number of simple numbers, right? You start counting from one...and you can count onto infinity.

Now, take just the even numbers, and just count them exclusively. If you just count the even numbers...you can count them into infinity, right?

But when you compare the infinite numbers against the infinite even-only numbers, which is the greater infinity?

It's a brain-twister, right? Counter-intuitive as it is, it makes sense. Some infinities are indeed bigger than others.

And it tells you why people get so jammed on this analog/digital dilemma. You think you can "see" the finiteness of digital audio on your computer monitor. But that's not the whole picture. It's just a graphic representation of one part of the process.
Title: analog = magnetic filed ; digital = square
Post by: Chuck on May 15, 2004, 08:26:47 am
Hi there,,

every representation of analog is connected to the instance that the signal is at one or more points in the chain:

A magnetic field.

Examples: Microphones, tubes, transformers, tape heads, pickup-cartridges, loudspeakers.

When we listen to analog recordings, we could have the insight, that the better the recording, the more often the signal passed through as a field.

I you compare f.e. the Eagles records, you get a very good feeling for the decline of audio quality that has happened over the years.

The record Eagles from '72 sounds wonderful.
Desperado '73 very very good.
On the border '74 very good.
One of these nights '75, still good, but now it starts becoming flat.
Hotel California '76, well many think it sounds good, actually not far as good as the old ones.
The Long Run '79 has lost all of the original Eagles quality sound.

I have all those records and can clearly hear the decline in quality that I point down to the fact, that tube-equipment was replaced in favor of transistor equipment.

The effect is that many parts in the whole recording chain, where the signal originally passed as a magnetic field, now it just passes as electric current through silicon transistors.

Although as measurements suggest that devices operating on a field create distortion and transistors are much more accurate, we know that without those fields, we cannot enjoy music at all.

Look at todays desperate attempts to get that kind of magnetic field sound with digital means.

You can indeed say, that the resolution of a field is indeed infinite or at least: it cannot be captured with bits and sample-rates.

But this is not necessary, as the purpose of playback equipment is to reintroduce those subtle harmonic structures.

The problem of digital playback is just ONE:

Square Waves.

All that we try to capture are sinewaves, and all our converters put out are square waves.

As you all know, squares consist of odd harmonics alltogether, so the main job of digital reproduction is filtering out those high-order odd stuff.

You can imagine that the larger the squares, the more difficult it is to filter them into a round wave-form.

Now can you reduce the size of the squares by going from 16 to 20 or 24 bits ? Indeed not.

If you want to have smaller squares, you need to increase sampling rate.

Charles Smile

Title: Re: analog = magnetic filed ; digital = square
Post by: Nika Aldrich on May 15, 2004, 08:34:00 am
Chuck wrote on Sat, 15 May 2004 13:26

You can imagine that the larger the squares, the more difficult it is to filter them into a round wave-form.


Chuck,

This is a completely erroneous and misleading statement.  

Nika.

Title: Re: analog = magnetic filed ; digital = square
Post by: Chuck on May 15, 2004, 09:03:42 am
Nika Aldrich wrote on Sat, 15 May 2004 14:34

Chuck wrote on Sat, 15 May 2004 13:26

You can imagine that the larger the squares, the more difficult it is to filter them into a round wave-form.


Chuck,

This is a completely erroneous and misleading statement.  

Nika.




Hi Nika,,

Try to think about it again, but an octave higher.

Charles Smile
Title: Re: George....what's the resolution of analog?
Post by: Former Oceanway drone on May 15, 2004, 11:17:51 am
Chuck wrote:

"I you compare f.e. the Eagles records, you get a very good feeling for the decline of audio quality that has happened over the years.

The record Eagles from '72 sounds wonderful.
Desperado '73 very very good.
On the border '74 very good.
One of these nights '75, still good, but now it starts becoming flat.
Hotel California '76, well many think it sounds good, actually not far as good as the old ones.
The Long Run '79 has lost all of the original Eagles quality sound."


I certainly have opinions about analog vs. digital and I have no intention of talking about them right now. That said, I do have a problem with Chuck's connecting the declining recording quality of Eagles albums with a "decline" in analog.

First, and more importantly, the first two Eagles albums were recorded by Glyn Johns. An engineer who aside from having great ears, also tended to record things simply, but with very good gear. After that Bill Szymzyck took over and started using MCI inline consoles, which, while quite versatile, can not be easily confused for Neves.

Second, Ampex ATR-124s came out at the beginning of the 1980s and can in no way be connected with the "decline" of analog. Indeed I would argue that it symbolized the apex of the analog tape machine. More generally, some amazing analog recordings came out in the early 1980s (e.g. Joni Mitchell "Wild Things Run Fast"; Dire Straits "Love Over Gold"; etc.

I disagree fundamentally with the premise that analog got worse over time.

Cheers,

Alan Tomlinson
Title: Re: George....what's the resolution of analog?
Post by: Curve Dominant on May 15, 2004, 12:24:26 pm
Quote:

posted by Charles:
Nika Aldrich wrote on Sat, 15 May 2004 14:34
Chuck wrote on Sat, 15 May 2004 13:26

You can imagine that the larger the squares, the more difficult it is to filter them into a round wave-form.

Chuck,

This is a completely erroneous and misleading statement.

Nika.



Hi Nika,,

Try to think about it again, but an octave higher.

Charles



Nika,

I got your message yesterday.

Good lord, no wonder you're exhausted. It seems they have us outnumbered.
Title: Re: George....what's the resolution of analog?
Post by: David Bock on May 15, 2004, 12:35:30 pm
"In any way you care to measure, even a $25 SoundBlaster sound card beats pretty much any analog tape recorder."
Wow, I thought it was pretty well known that we did not have, as of yet, a real complete set of tools to measure things we can hear (including compensation for the dramatic non-linearities of each person's hearing). Yes, we have many tests (measurements) that are useful and give some indications of device behavior, but they are simply "easiest path" devices, that is, measurements we CAN make but not really all the measurements we would WANT to make. So knowing that mankind's AVAILABLE audio measurement systems crudely scratch the surface of audio behaviour, one would then have to factor in one's experience to assist them in navigating the darkness of the audio jungle. My experience has shown:
Vinyl records (good & bad): more fun than CD's
Multitrack tapedeck: always elicits shock and awe from daw fed engineers
Musicians: very sensitive, and are responding to the awesome editing power of daw with some of the most uninteresting music ever.
Regards,
David Bock


Title: Re: George....what's the resolution of analog?
Post by: Chuck on May 15, 2004, 12:43:45 pm
Former Oceanway drone wrote on Sat, 15 May 2004 17:17


I certainly have opinions about analog vs. digital and I have no intention of talking about them right now. That said, I do have a problem with Chuck's connecting the declining recording quality of Eagles albums with a "decline" in analog.



Hi Alan,,

thanks for filling in the info on recording gear and engineers.

Of course there are great recordings being made after the 70's.

I did not want to say that available analog equipment is getting worse over time.

But in general terms, while cruising through my record collection, I am expecting good sound from late 60's to late 70's some to '82, then it appears to become increasingly difficult to obtain that rich hi-fidelity sound quality.

Btw. I also have the early Eagles records on CD with a sticker on them that says:"digitally remastered", and if you know and have the records, I would say the CDs are just unlistenable.

I don't blame it on digital or the CD format. But actually, I don't know who or what I would want to blame for it. For me, subjectively, it is just a decline in audio quality.

I have Joni Mitchell Hejira on vinyl, and I have the Travelogue album on CD. Both excellent, really very very good.

Lately I bought Joni Mitchell 'Both sides now' as 24/96 DVD-A. As I have Chesky 24/96 DVDs that are really excellent, I expected something.

But the Joni Mitchel DVD-A sounds like crap. I read the names Geoff Foster, Allen Sides and Bernie Grundman on the inlet. I don't know these guys personally, maybe you know them...

I have just no comprehension and no words for the decline in audio quality, that I have to face today.

I just wonder: "How did they manage to have that wonderful sound, almost half a century ago, and what are the reasons, that make it so difficult to achieve today ?"

Charles Smile
Title: Re: George....what's the resolution of analog?
Post by: ted nightshade on May 15, 2004, 12:54:41 pm
I well believe that those pushing 192 as a *standard* have ulterior financial motives in doing so.

I also believe that many of those posting here are pleased to be able to prove on paper that theoretically the digital systems they have invested in are superior to any and all analong tape machines- this may well serve as a way of rationalizing not undertaking the pain in the ass that is analog tape recording. A pain in the ass, but with excellent machines and some work you can give a lot of your signal processors a rest and achieve qualities of sound very pleasant to humans- I can't help but notice there's a lot of wannabe analog systems available for digital these days...

I'm talking about tracking to analog, not dumping digital stuff onto analog tape as an effect. Actually I very much appreciate the relative transparency of exceptional digital recorders (no others need apply), to the extent that that transparency exists, when it comes to mixdown- one generation of analog tape suits me fine.

Anybody care to prove on paper that photography is superior to oil painting?
Title: Re: George....what's the resolution of analog?
Post by: chrisj on May 15, 2004, 02:32:46 pm
Ethan Winer wrote on Fri, 14 May 2004 13:16


In any way you care to measure, even a $25 SoundBlaster sound card beats pretty much any analog tape recorder.


Um- I don't think so. I think perhaps what you mean is, <i>'with regard to the accuracy of continuous test tones over a frequency range of arguably 20-20K, a $25 SoundBlaster sound card beats pretty much any analog tape recorder.'</i>

You can measure truncation artifacts. You can measure jitter. You CAN measure some of the phenomena that are good at making digital audio unpleasant. For that matter, you can measure reconstruction filter 'ringing' (really the aftereffect of a brickwall filter, and not a resonance like other sorts of 'ringing') to the point where you can tell when it's going to distort the DAC. You can measure that down to ten decimal places for a given signal- and such signals are hardly impossible- modern pop and rock is loaded with that stuff thanks to overcompression and overlimiting.

I'm sorry, but there is no scientific basis for behaving like a Sound Blaster beats a Studer. You're looking at way too narrow a set of criteria. Hell, it's well known that inharmonic distortion is much easier to hear than harmonic distortion. Phenomena like the tape machine head bump the Studer would have is significant in frequency response terms, but extremely unobjectionable. What about the on-the-fly SRC built into some Sound Blaster Audigys? These things can be both measurable, and acutely unpleasant. Please don't behave like 10% of second harmonic distortion is more obnoxious than 5% of five and 3/8ths harmonic distortion- or a mathematically related, not harmonically related, distortion (akin to ring modulation)

As far as the resolution of analog- you can hear through noise, otherwise we'd be going constantly deaf everytime a car or airplane passed by. It's not so much about noise, still less about analog really delivering a wider frequency range. It's more about the KINDS of distortion analog is subject to, being a heck of a lot less objectionable than the KINDS of distortion even the best digital is subject to.

Title: Re: analog = magnetic filed ; digital = square
Post by: chrisj on May 15, 2004, 02:40:53 pm
Chuck wrote on Sat, 15 May 2004 08:26


All that we try to capture are sinewaves, and all our converters put out are square waves.
As you all know, squares consist of odd harmonics alltogether, so the main job of digital reproduction is filtering out those high-order odd stuff.



Mm. No. Let me put it this way:
There are no squares, really. You're looking at the visual representation of a bunch of numbers designed to tell the converter what kind of SINES to put out.
The only time you'd be hearing squares is if you were using one of those funky DACs with no reconstruction filter. And that's actually not technically correct, though there are some things about it that count as advantages...
The squares you're thinking of, you might be better served by thinking of them as lists of numbers, not as a waveform. Nothing is ever about trying to present that information as squares. The DAC wants to present it as sines again, that's what it's for. That's what a reconstruction filter is for.
What you should be looking into is not 'squares', not increasing frequency range (necessarily), but the types of harmonic and inharmonic distortion generated by each kind of recording.
Title: Re: George....what's the resolution of analog?
Post by: Han S. on May 15, 2004, 05:34:13 pm
Quote:

I just wonder: "How did they manage to have that wonderful sound, almost half a century ago, and what are the reasons, that make it so difficult to achieve today ?"

Charles Smile


That's a very good point and it makes me wonder as well.
In the late 50's there wasn't any multitrack, just two tracks and some recordings of that era sound much better than anything of today. Musta been the engineers (like Bill Putnam sr).
Title: Re: George....what's the resolution of analog?
Post by: Brent Handy on May 15, 2004, 06:08:10 pm
My World wrote on Sat, 15 May 2004 03:13

I have been "begging" sound processing companies for several years to develop 28-bit processors!  C'mon guys!


I believe that there is a 28-bit processor.  But it is not a true usable 28-bit any more than a 24 is really 24.

Lets say that they get to 32, so that it performs at 28.  Will the microphones used to record hinder the process?
Title: Re: George....what's the resolution of analog?
Post by: Phillip Graham on May 15, 2004, 10:20:18 pm
jazzius wrote on Fri, 14 May 2004 12:56

George, we hear about the resolution of digital all the time.....24 bits, 44.1, 192.....2.8 million whatevers....

...do you know if anyone has ever worked out the resolution of analog?.....how many bits would it be equivelent to?.....i know this is bit of a strange question, but i'd love to be able to give my customers a smart-arse answer for why analog sounds better then digital...

...cheers.....Darius


Hello Darius,

I am going to attempt to answer your original question, since this thread has nearly as much erronius information as the entire 192khz thread.  I think you will find this post far reaching, and hopefully educational.

Let's start by trying to define "resolution."  A common definition for this in physics is the Ralyeigh limit for optical "resolution."  It is approximately equal to .66*lambda.  It says that two objects closer together than .66*wavelength cannot be focused on well enough to tell one from the other.

In some sense the Nyquist frequency can be thought of as the limit of the (frequency,wavelength,length-however you want to look at it) "resolution" of a discrete time system.  Below the nyquist frequency all waveform content is completely captured, and above the nyquist frequency it aliases back into the lower frequencies (an erronius result).

It is important to understand that there is a difference between "discrete time" systems and "digital" systems.  Quantitization is a completely separate process from discrete time sampling.

Your ADC takes an "analog" voltage measurement at each sample, and then represents that as digital word of given length.  The longer the world length, the greater the difference in level between the quietest and loudest sounds.  You could view this differential as a measure of "resolution" if you wanted.

In the ancient world, Descarte proposed that the number line was continuous, a revolutionary idea.  But, as science and math progressed, many situations where discrete solutions, and phenomena, were observed.

So, with that in mind, we now shift to some physics behind "analog" electronics.

The fundamental magnetic moment observable in the known universe is that of an electron.  This number is known as the Bohr Magneton, and its value is 9.27x10-24 Joules/Tesla.

Materials used for magnetic properties have varying degrees of unpaired electrons, and the orientation of the quantum "spin" of these electrons eventually determines on a macroscale the magnetic behavior involved.  The formation of magnetic domains is the topic of full books.  I personally recommend the classic "Physical Properties of Crystals: Their Representation by Tensors and Matrices" by J. F. Nye.

The formation of magnetic domains is a dissipative and nonlinear process.  This can be represented by a hysteresis loop.  This hysteresis loop shows the nonlinear behavior of the magnetic media with applied field.  The positive portion of the curve looks something like the compressor curve you would draw in a DAW.  They do form a complete loop, though, and the volume of the center of the loop tells you how much energy was lost in the whole write/unwrite process.

While there are other magnetic responses (magnetoresistance for example), I believe the analog tape recorders of the recording world used simple induction to read and write their data.  A similar "read/write" process is the process of transferring the magnetic field from the primary of a guitar amplifier output transformer to the secondary, coupled by a magnetizable core material.  The nonlinear nature of the hysteresis curve gives much of the warm gooeyness of the analog medium.

I am tempted to talk about other subjects, such as electron thermalization, johnson noise, etc. but I don't want to devote further time to this before I see if it is heading in the direction you were looking to comprehend.
Title: Re: George....what's the resolution of analog?
Post by: jackpine on May 15, 2004, 11:07:36 pm
 He took the words right out of my mouth. Razz
Title: Re: George....what's the resolution of analog?
Post by: Zack Reinig on May 16, 2004, 12:49:32 am
I think what darius was referring to as 'better' is the three dimensional throw of analog (resulting from frequency dependent tape compression effect on transients) vs. the flat 2 dimensional feel of digital, and the lack of the easily audible distorted high end above 8k you can hear in straight digital 2 track mixes (even thru fantastic converters).  In my opinion, analog sounds more life like at times due to the same sort of distortion that occurs when the human ear is subject to overbearing spl (drum kit being played).
Title: Re: George....what's the resolution of analog?
Post by: jazzius on May 16, 2004, 03:48:03 am
Thanks Phill......yeah, that's more what i meant....i wasn't asking about how well analog can be captured in the digital domain....only about the resolution of analog itself....looks like you're the only one who got it!.....i'm afraid most of what you wrote flew over my head but it was an interesting read, anyway!.....cheers!
Title: Re: analog = magnetic filed ; digital = square
Post by: Chuck on May 16, 2004, 08:29:43 am
chrisj wrote on Sat, 15 May 2004 20:40


There are no squares, really. You're looking at the visual representation of a bunch of numbers designed to tell the converter what kind of SINES to put out.
The only time you'd be hearing squares is if you were using one of those funky DACs with no reconstruction filter. And that's actually not technically correct, though there are some things about it that count as advantages...
The squares you're thinking of, you might be better served by thinking of them as lists of numbers, not as a waveform. Nothing is ever about trying to present that information as squares. The DAC wants to present it as sines again, that's what it's for. That's what a reconstruction filter is for.
What you should be looking into is not 'squares', not increasing frequency range (necessarily), but the types of harmonic and inharmonic distortion generated by each kind of recording.



Hi Chris,,

yes, I'm a funky guy with funky converters that put out funky squares that one may find many different ways in interpreting them into funky sines.

http://amm.haan.de/pn/0-ovs.jpg

In the pic I have used a not-so-good audio transformer, and tuned the circuit to ring a little at fs (in this case 44.1kHz). What you see on the top trace is the "filtered output". This is a very good sounding filter. The only problem is to get those bad transformers. With good transformers it don't work right...

You may think that modern DACs don't work with squares, because at the output you see sines plus noise, but they do. And the noise at the output are the HF residuum of the square-filtering-process.

By increasing the sampling frequency we get more but smaller squares. Oversampling does the same, except that the smaller squares are invented in between the real samples.

It is easier to filter small amplitude squares and on the other hand almost impossible to filter a 1-bit signal - like DSD - into fidelity.

Charles Smile
Title: Re: George....what's the resolution of analog?
Post by: sfdennis on May 16, 2004, 09:31:55 am
Hey Charles, that is a very funky converter indeed. What is it exactly? At first blush, it looks like there is absolutely no reconstruction filter working. Also please let us know the time & voltage division settings are on that picture. -Dennis
Title: Re: George....what's the resolution of analog?
Post by: Chuck on May 16, 2004, 11:45:11 am
sfdennis wrote on Sun, 16 May 2004 15:31

Hey Charles, that is a very funky converter indeed. What is it exactly? At first blush, it looks like there is absolutely no reconstruction filter working. Also please let us know the time & voltage division settings are on that picture. -Dennis


Hi Dennis,,

it is the output of a Burr-Brown PCM1704. I did some glue logic, and so was able to remove the DF1704 oversampling filter, that I was used to employ.

So the stair that you see, is just the exact amplitudes, stored on the CD. The stair signal unfiltered sounds not so good, as you might guess, and with RC filters, you only smooth the first edge, but not the second.

So I tried this audio-transformer and it works and sounds very good.

I like higher sampling rates, because not only more information is captured, but also with higher sampling frequencies the steps are smaller in amplitude and filtering is much easier.

One of the big advantages of higher sampling rates is that digital- or oversampling-filters (with their look-ahead and start ringing before the signal) become obsolete.

Well, in my opinion, they should not be used anymore - in other words: don't let a mathematician interpret audio signals.

I don't remember the scope settings, but at 44.1kHz each stair should be about 23
Title: Re: George....what's the resolution of analog?
Post by: Ethan Winer on May 16, 2004, 12:34:46 pm
David,

> Yes, we have many tests (measurements) that are useful and give some indications of device behavior, but they are simply "easiest path" devices, that is, measurements we CAN make but not really all the measurements we would WANT to make. <

Everything important in audio that needs to be measured can be measured using currently available tools. These measurements can resolve to a level much finer/lower than anyone's ear can hear. There are no magical properties that we can hear, but which science has not yet identified. If you believe otherwise, I'd love to see some evidence.

--Ethan
Title: Re: George....what's the resolution of analog?
Post by: Ethan Winer on May 16, 2004, 12:41:43 pm
Charles,

> How did they manage to have that wonderful sound, almost half a century ago, and what are the reasons, that make it so difficult to achieve today? <

Years ago music was recorded and mixed in real recording studios that had large rooms. The better studios also had sufficient bass trapping and other acoustic treatment so the recordings were not permeated with the "small room" sound we hear so much today. And the mix engineers were able to hear what they were doing much more accurately than folks today who work in small untreated bedrooms.

All of the gear used today beats all of the gear used years ago in every way you care to assess gear. But the rooms have gotten much smaller, and a lack of proper acoustic treatment compounds the problem.

--Ethan
Title: Re: George....what's the resolution of analog?
Post by: Ethan Winer on May 16, 2004, 12:49:59 pm
Chris,

> You can measure truncation artifacts. You can measure jitter. <

You can measure noise, distortion, and timing errors like jitter on a Studer too. The jitter caused by tape scrape on even the best analog tape recorder is 100 times worse than the jitter of an SB Live sound card.

> there is no scientific basis for behaving like a Sound Blaster beats a Studer. <

And there is no scientific basis for behaving like a Studer beats a SoundBlaster. If you believe you know of such a basis, I'd love to hear it.

> the tape machine head bump the Studer would have is significant in frequency response terms, but extremely unobjectionable. <

Okay, you may well enjoy hearing a slight bass boost at a pleasant frequency. So why not just add that with EQ? How can you argue with a straight face that an obvious flaw like a skewed frequency response is a feature or not objectionable?

> What about the on-the-fly SRC built into some Sound Blaster Audigys? These things can be both measurable, and acutely unpleasant. <

A proper double-blind test will put that to bed quickly.

--Ethan
Title: Re: George....what's the resolution of analog?
Post by: dwoz on May 16, 2004, 01:35:41 pm


Let me give a shot at it...what the hey, eH?


Ok, "resolution".

when an analog signal is sampled, it is essentially 'sliced' into segments, each of which has a certain width in time. The width of the 'slice' is dependent on how many slices you make in a second...the sample rate.

These 'slices' have to be made small enough that the signal being sampled cannot change direction TWICE inside the slice. (that's the nyquist thingy).  Another way of saying this is that the frequency of the signal must be limited so it CAN'T go south then north inside a single slice.

OK, so when we check the voltage of this sample, we really have to make TWO measurements...the absolute level, and also the slope of the wave. without these two, we don't really know the complete behavior of that signal. But the measure we take is only the level.  BUT, because of the definition we've given, that the signal will only go up, or go down, or go up and down ONCE within the sample, we can check the samples on either side and infer a slope for the width of the sample.  It isn't perfect, but its pretty much good enough for our purposes.

What we're talking about here is QUANTIZATION ERROR.  by knowing both the absolute value of the sample (either the leading edge, the exact middle, or the tail edge) and the interpolated slope, we can make some pretty good guesses about what "number" we should put in the output stream, so our DAC can reconstruct an analog signal that is very much like our input.

So, the sample rate controls HOW WIDE (or long) that sample is in time.

The bit depth controls how fine the discrete measurements we can make can be accurately captured.  If we're trying to represent the whole dynamic range of the signal with just 8 bits, then we have to make some pretty gross approximations of the value of the particular we just measured. If we're using 28 bits, then the chance that the EXACT value of the sample that we just measured is only a tiny bit off a discrete integer that we can record, is much better.


It should be obvious that BOTH the sample rate, and the bit rate, contribute to the QUANTIZATION ERROR.  If I have a very high sample rate, then the more likely that my measurement of the slope is close to the actual value. I can rely on the absolute value of the sample, and less on the slope...and the higher the bit depth, the closer the measured value will be to one I can record.  Remember, I have to round any 'inbetween' floating point value to an integer.

But, being able to calculate the slope of the signal, lets me "find" a lot more information about that analog signal than is immediately apparent in the raw data.

So, resolution of digital signals is dependent on both the sample rate, and the bit depth, to some extent.

In the context of what I've just said, the "resolution" of analog signals would be to all intents and purposes, infinite. Not REALLY infinite of course, and when I can count individual electrons and quanta, then we can enter that discussion of just HOW INFINITE it is.

As a little social aside...so good to have curveDominant around to save us newbies from ourselves.

Reread Zoesch's comments...

dwoz
david wozmak
Title: Re: George....what's the resolution of analog?
Post by: Bill Mueller on May 16, 2004, 01:48:35 pm
Wow,

This thread is all over the place. I am most comfortable with Phill Graham's response however I would like to add a couple of things.

First lets define "analog". Are we speaking of analog electronics or storage?

In analog electronics, functional resolution (detail) is determined by high frequency bandwidth. If high frequencies come in but do not go out of a circuit, the resolution is reduced. Noise and distortion both limit resolution by introducing signal components not found in the source.

In order to create an "analog" (aproximate representation) of an acoustical event, there needs to be a series of conversions of energy (transductance), by a series of transducers, each with unique resolution limiting parameters.

The first transducer stage is mechanical. The diaphram of your microphone moves in approximate syncronicity with compression and rarefaction states of molecular movement in the air. The resolution limiting factor here is mass. The heavier the diaphram, the slower its response and the more bandwidth limiting is its perfomance.

The second stage is either magnetic or electrical. Ribbon and dynamic mics transduce mechanical motion into magnetic energy and condenser mics convert that motion directly into electrical energy. Phil's description regarding magnetic transfer applies wherever transformers are used. Nonlinear transfer due to the hysteresis curve adds both noise and distortion, both resolution limiting factors.

Once into the electronic stage, there are any number of limiting factors regarding high frequency response however, my view has always been that noise is a major mitigating factor regarding high frequency performance. Since noise is associated with all frequencies in a circuit, making a circuit's high frequency performance wider than necessary, will introduce noise unnecessarily. Building a circuit both wide and quiet is the trick. I won't go any further here because the best of the best can give their views on how they accomplish this.

With analog STORAGE high frequency performance is limited by the speed of the individual magnetic domains on the tape as they go by the record/play heads. There are two ways of increasing high frequency performance. First you can move the domains by the head at a faster pace thereby spreading the high frequency signals over more physical domains. This is why a 30ips Studer A-80 MkIII can record 30khz and your analog cassette machine is limited to about 12khz. The other way is to reduce the individual size of the domains. The problem here is to maintain sufficient "retention" in the domains so that they will not loose their magnetic energy. Larger domains naturally have better retention. Better retention means better signal to noise specs.

Again, the magnetic hysteresis curve defines the linear transfer capability of a magnetic medium. We use biasing to linearize magnetic tape, but at the cost of adding noise. Designing the best compromize between noise, distortion and bandwidth is the art.

I see the domain size/speed issue as being the analog storage analogy (sorry) to sample rate in a digital system. The higher the sample rate (analog tape speed) the better the high frequency performance.

As regards to the sine/square wave storage issue. Anyone who believes that we store perfect waveforms on an analog recorder better take a closer look at a 20khz sine wave at +4 on almost any analog recorder output.

One last pet peeve. It is necessary to have ALL test parameters available to believe ANY stated performance specs and ANY piece of gear, analog or digital.

Best regards,

Bill

Title: Re: George....what's the resolution of analog?
Post by: George Massenburg on May 16, 2004, 01:58:07 pm
gtphill wrote on Sat, 15 May 2004 21:20


[...]
Let's start by trying to define "resolution."  A common definition for this in physics is the Ralyeigh limit for optical "resolution."  It is approximately equal to .66*lambda.  It says that two objects closer together than .66*wavelength cannot be focused on well enough to tell one from the other.

In some sense the Nyquist frequency can be thought of as the limit of the (frequency,wavelength,length-however you want to look at it) "resolution" of a discrete time system.  Below the nyquist frequency all waveform content is completely captured, and above the nyquist frequency it aliases back into the lower frequencies (an erronius result).
[...]
I am tempted to talk about other subjects, such as electron thermalization, johnson noise, etc. but I don't want to devote further time to this before I see if it is heading in the direction you were looking to comprehend.

Phil,

Thanks very much for your notes.  Now, this is alot closer to the discussion that I think  we should be having about digital audio.  I'm currently having a enlightening discussion off-line with Jim Johnston about quantizing multi-channel audio and differential resolution in the time-domain.

To those of you who are dreaming of perfect waveforms, I have to reiterate what others in these two threads are saying very clearly, "You're barking up the wrong tree."  IT'S NOT BANDWIDTH.  I, like others, wish you guys would first just do the reading leaving your at-best-unproductive prejudices behind.

Perhaps what we should do is to start a thread where we do not allow any of the "magic thinking" stuff.

Stay tuned.

George
Title: Re: George....what's the resolution of analog?
Post by: Nika Aldrich on May 16, 2004, 02:05:20 pm
David,

It's a good attempt.  Allow me to throw in some corrections below.

dwoz wrote on Sun, 16 May 2004 18:35



when an analog signal is sampled, it is essentially 'sliced' into segments, each of which has a certain width in time.


No.  The samples have no "width" in time at all.  They are momentary and instantaneous samples of the amplitude of the waveform at moments in time and do not imply what comes before or after them.  Only on a computer screen are we led to think that the samples have width, because a computer screen tries to draw it up there in a way that is pleasing to the eye.  In reality, sample points should be given to us as mere dots in space with no connecting line between them at all.  That would help drive home the point that the samples are infinitely short in time.

Quote:

These 'slices' have to be made small enough that the signal being sampled cannot change direction TWICE inside the slice. (that's the nyquist thingy).  Another way of saying this is that the frequency of the signal must be limited so it CAN'T go south then north inside a single slice.


More complicated than just going north and then south between two samples.  Higher frequency content doesn't always manifest itself like that.  Higher frequency content also causes steep angles and corners and much more.  All of those behaviors are illegal also.  Trying to adhere to Nyquist by means of discussing movement between samples implies a degree of misunderstanding about the genius of Nyquist and the role of reconstruction filters.  

Quote:

OK, so when we check the voltage of this sample, we really have to make TWO measurements...the absolute level, and also the slope of the wave. without these two, we don't really know the complete behavior of that signal. But the measure we take is only the level.  BUT, because of the definition we've given, that the signal will only go up, or go down, or go up and down ONCE within the sample, we can check the samples on either side and infer a slope for the width of the sample.  It isn't perfect, but its pretty much good enough for our purposes.


No no no, and this is the dangerous part that people are led to believe.  This is also the beauty of Nyquist.  Nyquist came forth with a radical theory that you can know only ONE piece of information in order to completely accurately reconstruct the waveform, and that one piece is the amplitude at regular intervals of time.  With a little trick math the ENTIRE rest of the waveform can be 100% of the waveform can be entirely and accurately reconstructed with proper amplitude, frequencies, and phase.  In other words, we don't need to know the slope!!  If we know only the amplitude of regular intervals Nyquist tells us that we can figure out the slope.  You must admit that this is a pretty revolutionary concept - one that defies common logic and simple intuition.  And THAT is why it took over 20 years before a mathematician proved Nyquist correct.

So the point is that digital audio is not at all imperfect as you imply because we have all the information needed to reconstruct the waveform.

Quote:

What we're talking about here is QUANTIZATION ERROR.  by knowing both the absolute value of the sample (either the leading edge, the exact middle, or the tail edge) and the interpolated slope, we can make some pretty good guesses about what "number" we should put in the output stream, so our DAC can reconstruct an analog signal that is very much like our input.


I'm not following this yet but I don't believe you're on the right path?  Quantization error is only the error yielded by having to round the sample up or down to the latest quantization step when we take the sample.

Quote:

So, the sample rate controls HOW WIDE (or long) that sample is in time.


Semantical correction - it controls HOW OFTEN the samples are taken, not how wide the samples are.

Quote:

The bit depth controls how fine the discrete measurements we can make can be accurately captured.  If we're trying to represent the whole dynamic range of the signal with just 8 bits, then we have to make some pretty gross approximations of the value of the particular we just measured. If we're using 28 bits, then the chance that the EXACT value of the sample that we just measured is only a tiny bit off a discrete integer that we can record, is much better.


Right!

Quote:

It should be obvious that BOTH the sample rate, and the bit rate, contribute to the QUANTIZATION ERROR.


Absolutely not!!!  Only the bit depth relates to quantization error.  Sample rate is completely unrelated.

Quote:

If I have a very high sample rate, then the more likely that my measurement of the slope is close to the actual value. I can rely on the absolute value of the sample, and less on the slope...and the higher the bit depth, the closer the measured value will be to one I can record.  Remember, I have to round any 'inbetween' floating point value to an integer.


no, no, no, as I explained above.

Quote:

So, resolution of digital signals is dependent on both the sample rate, and the bit depth, to some extent.


Errr...language like this is specious and not the most descriptive way to describe what is happening.  

Quote:

In the context of what I've just said, the "resolution" of analog signals would be to all intents and purposes, infinite. Not REALLY infinite of course, and when I can count individual electrons and quanta, then we can enter that discussion of just HOW INFINITE it is.


Again, not the best way to describe, for it denies the reduction in accuracy on the analog signal due to added noise and distortion.  Since digital signals add less noise and distortion it is hardly accurate to say that analog signals have more "resolution," and is one of the reasons why it is best to shy away from that term - it does not do an accurate job of communicating anything pertinent about waveforms.  While one can look at dictionary definitions and find that the term is theoretically relevant, it is actually quite inappropriate and doesn't adequately describe useful information in the context of analog vs. digital recordings.

Nika.
Title: Re: George....what's the resolution of analog?
Post by: dwoz on May 16, 2004, 02:26:39 pm
I don't agree that noise is a limiter of resolution.  I find that to be a red herring.  Of course noise is a factor, but as many others have noted, and as many including myself have heard time and time again, content can be discerned under the noise floor.

Noise is never good, but noise floor isn't necessarily a boundary.


also, I completely understand that a sample is an instant, without width...thus my "leading edge, middle, trailing edge" qualification of the "width" of a sample.  the sample represents a choice of a single value among perhaps many inside the span of time being represented by that sample.

I stand by my assertion that sample rate has to do with quantization error...as the more time between samples, the more opportunity to pick a value that doesn't represent the activity within the sample.  I definitely grant to you the point that bit depth has more effect on quantization error, perhaps by an order of magnitude or more, but still it IS A FACTOR.


And again, I stated that we only record the absolute value, not the slope, because we can interpolate slope using adjacent values, not having to resort to "complex" calculus and defining slope and value....as you state, after all, that because of nyquist, we don't see real values of slopes that diverge significantly from our ability to interpolate their values.


thanks for your reply.

dwoz
Title: Re: George....what's the resolution of analog?
Post by: dwoz on May 16, 2004, 02:31:10 pm


Another thing....


ANALOG RESOLUTION.   I suppose that a 1/2" 2 track tape that is capable of slurping up +18db peaks, would "beat" a cassette deck running 1/16" track width that can barely manage -10db levels?

Or, a board with 24volt rails, compared to one with 12 volt rails...being able to pass +24db signal without mangling it, compared to one that decapitates a +12db signal as a matter of course?

Is there fodder for discussion there?

dwoz
Title: Re: George....what's the resolution of analog?
Post by: sfdennis on May 16, 2004, 02:50:51 pm
Charles, I just had to retract this post. It was all wet. -Dennis
Title: Re: George....what's the resolution of analog?
Post by: Jim Dugger on May 16, 2004, 04:35:39 pm
dwoz wrote on Sun, 16 May 2004 13:26

I stand by my assertion that sample rate has to do with quantization error...


May I ask Nika or one of the others here to help explain something to me in clearer (layman) terms?

It is true that the time and frequency domain are quite linked, correct?  Afterall, there are well known ways to covert information of one kind into the other.

So, does it stand that increasing the sampling rate is somehow (within some reasonable limits) equal to adding one bit to the frequency domain?

In other words, is a signal, optimally represented at 16/88.2, essentially equal to a signal optimally represented at 17/44.1?  You may assume the signal not to contain out-of-bandwidth information.

If not, where in the system of A2D, DSP then D2A do the time/frequency domain correlations break down?  Or, did they never exist at all, and are only available using math on already digital signals?

The answer may help several pieces of stone presently rattling around in my head come together...

--Jim
Title: Re: George....what's the resolution of analog?
Post by: Bill Mueller on May 16, 2004, 07:56:20 pm
dwoz,

I'm not sure by your post if you were answering me regarding noise being a limiting factor to resolution, however if we define resolution as fidelity (the truest possible conversion of an acoustic event) then noise is a limiting factor. Any signal coming out of a device that is not present at the input, limits fidelity.

I absolutely agree that signal can be heard below noise in an analog system. If the signal is at a different frequency than the noise, then it can be heard even better. This is called the masking effect. If I recall, the masking effect works down to about 6 db below signal, meaning that you can hear signal about 6 db below noise if that noise is present at that frequency. If anyone has better figures here I would appreciate it.

To me analog noise is sort of like digital bit depth in its affect on the signal. While you can hear low level signal in both analog and digital systems, they are each distorted by the medium.

Many don't seem to realize that recordings made 6 db below clip on digital systems, result in one less bit than maximum, ie -6 db on a 16 bit system results in a 15 bit (1/2 resolution) recording, -12 db results in a 14 bit recording (1/2 resolution of the 15 bit recording) and so on. Therefor as you fade out a signal, the resolution drops precipitously. Crank up your fades sometime for a truly horible experience.

A similar thing happens in analog except that to my ear, it sounds significantly better.

Best regards,

Bill
Title: Re: George....what's the resolution of analog?
Post by: Zoesch on May 16, 2004, 09:36:19 pm
Bill Mueller wrote on Mon, 17 May 2004 09:56

dwoz,

I'm not sure by your post if you were answering me regarding noise being a limiting factor to resolution, however if we define resolution as fidelity (the truest possible conversion of an acoustic event) then noise is a limiting factor. Any signal coming out of a device that is not present at the input, limits fidelity.


Resolution is your ability to resolve, noise does indeed limit what you can resolve due to masking, but it doesn't really change your measurement resolution.

Quote:


To me analog noise is sort of like digital bit depth in its affect on the signal. While you can hear low level signal in both analog and digital systems, they are each distorted by the medium.


I don't follow this... the noise floor has an effect on headroom, say if you calibrate your A/D chain to reach 0dBFS exactly when you top in headroom then yes, analog noise will definitely have an effect on how well you can convert the signal, the lower the noise the more precise your sampling would be at lower levels.

Quote:


Many don't seem to realize that recordings made 6 db below clip on digital systems, result in one less bit than maximum, ie -6 db on a 16 bit system results in a 15 bit (1/2 resolution) recording, -12 db results in a 14 bit recording (1/2 resolution of the 15 bit recording) and so on. Therefor as you fade out a signal, the resolution drops precipitously. Crank up your fades sometime for a truly horible experience.



Yep, we all know the beauties of hard bound linear systems... that's why that BS about recording hot to digital was so wrong, but it was perpetuated around without people questioning it. Then you need to take into account how summing is implemented in your DAW of choice, but that is for another (presumably lenghty) debate.

Quote:


A similar thing happens in analog except that to my ear, it sounds significantly better.



Simply because in the analog domain the transfer curves aren't fully linear, so at high gain you are compressing the signal. And, the signal you clip once you run out of headroom has a more balanced content of odd and even harmonics as opposed to a hard-clipped digital signal which contains mainly odd harmonics.

A good designed system should avoid that, but again that's been debated 'till kingdom come, and some people are quite religious about their DAWs.
Title: Re: George....what's the resolution of analog?
Post by: hollywood_steve on May 16, 2004, 10:20:46 pm
All of the gear used today beats all of the gear used years ago in every way you care to assess gear. But the rooms have gotten much smaller, and a lack of proper acoustic treatment compounds the problem.

That first sentence is a loaded statement that shouldn't pass without comment.  

every way you care to assess gear

the only way that really matters is how it sounds.  And I'll take the SOUND of classic analog gear any day, and so will a lot of people who might think otherwise.

for example, I'll take

mics: a pair of (you choose: Neumann u47/48/M49/M50, RCA 44/77d, AKG c12 / Telefunken 251, among others)

console:  API 1604 or EMI REDD37

recorder: Studer A800 1" 8trk and Ampex ATR102 2trk

in any room at any time against the best of 2004 (and there is some AMAZING gear made by some small companies these days).  At some point the only "improvements" are discerned by test equipment.  I'm not the only one who thinks the best analog gear of the 70s was already as good as gear needed to be; it was just too expensive for all but the best studios. All we've done since then is made decent gear available to the masses; unfortunately, at the same time we have lowered the bar for what passes as acceptable commercial "product."



Title: Re: George....what's the resolution of analog?
Post by: Brent Handy on May 16, 2004, 10:44:04 pm
Chuck wrote on Sat, 15 May 2004 17:43

Former Oceanway drone wrote on Sat, 15 May 2004 17:17


I certainly have opinions about analog vs. digital and I have no intention of talking about them right now. That said, I do have a problem with Chuck's connecting the declining recording quality of Eagles albums with a "decline" in analog.



Hi Alan,,

thanks for filling in the info on recording gear and engineers.

Of course there are great recordings being made after the 70's.

I did not want to say that available analog equipment is getting worse over time.

But in general terms, while cruising through my record collection, I am expecting good sound from late 60's to late 70's some to '82, then it appears to become increasingly difficult to obtain that rich hi-fidelity sound quality.

Btw. I also have the early Eagles records on CD with a sticker on them that says:"digitally remastered", and if you know and have the records, I would say the CDs are just unlistenable.

I don't blame it on digital or the CD format. But actually, I don't know who or what I would want to blame for it. For me, subjectively, it is just a decline in audio quality.

I have Joni Mitchell Hejira on vinyl, and I have the Travelogue album on CD. Both excellent, really very very good.

Lately I bought Joni Mitchell 'Both sides now' as 24/96 DVD-A. As I have Chesky 24/96 DVDs that are really excellent, I expected something.

But the Joni Mitchel DVD-A sounds like crap. I read the names Geoff Foster, Allen Sides and Bernie Grundman on the inlet. I don't know these guys personally, maybe you know them...

I have just no comprehension and no words for the decline in audio quality, that I have to face today.

I just wonder: "How did they manage to have that wonderful sound, almost half a century ago, and what are the reasons, that make it so difficult to achieve today ?"

Charles Smile


And to think that all those great, flat records were mixed and monitored on those  JBL 4311's and the like.  What a testament to fine skill.

This is what blows me away about people critiquing other's work.  Maybe, just maybe the artist/engineer wanted the result that you hear?  Maybe your hearing is jaded by the romance (or lack there of) of a particluar time in your life.  Or maybe, that your "crap" sound from the LP's might be related to the mastering/pressing from a record club, etc.

I have listened to records from my youth, and remember them being much better than what they actually sound.  Granted CD's do sound different than records, and you don't get the words that you can read without a magnifying glass, the cool artwork, and the smell of vinyl. I don't know about you, but I gave up the Grado turntable long ago.  I enjoy pop free, rumble free, scratch free music.  What I like best is that I can get 10x in the peach crates. LOL
Title: Re: George....what's the resolution of analog?
Post by: Zoesch on May 16, 2004, 11:37:25 pm
hollywood_steve wrote on Mon, 17 May 2004 12:20

the only way that really matters is how it sounds.  And I'll take the SOUND of classic analog gear any day, and so will a lot of people who might think otherwise.

for example, I'll take

mics: a pair of (you choose: Neumann u47/48/M49/M50, RCA 44/77d, AKG c12 / Telefunken 251, among others)

console:  API 1604 or EMI REDD37

recorder: Studer A800 1" 8trk and Ampex ATR102 2trk

in any room at any time against the best of 2004 (and there is some AMAZING gear made by some small companies these days).  At some point the only "improvements" are discerned by test equipment.  I'm not the only one who thinks the best analog gear of the 70s was already as good as gear needed to be; it was just too expensive for all but the best studios. All we've done since then is made decent gear available to the masses; unfortunately, at the same time we have lowered the bar for what passes as acceptable commercial "product."






I think you are right from the sonics point of view, there was of course very good equipment made in the 80's and 90's (Mainly FX boxes) but when it came down to consoles I think the late 70's and early 80's produced the best designs of them all.

One problem though, although it'd make sense for analog consoles to have become cheaper over time, the reality is, good designs are hard to manufacture and require extensive design resources, most mass produced consoles tend to sound bad just because they were designed with cheap and quick manufacturing in mind,
Title: Re: George....what's the resolution of analog?
Post by: oudplayer on May 17, 2004, 02:13:55 am
Ethan Winer wrote on Sun, 16 May 2004 09:41

Charles,

> How did they manage to have that wonderful sound, almost half a century ago, and what are the reasons, that make it so difficult to achieve today? <

Years ago music was recorded and mixed in real recording studios that had large rooms. The better studios also had sufficient bass trapping and other acoustic treatment so the recordings were not permeated with the "small room" sound we hear so much today. And the mix engineers were able to hear what they were doing much more accurately than folks today who work in small untreated bedrooms.


I don't believe that a comparison of today's bedrooms and yesteryear's top-flight studios is reasonable. There are many people that are a part of this discussion (myself included) who regularly work in quite large recording facilities, in amply-sized concert halls, and basically in spaces that are no larger nor smaller than those of yesteryear. Working in those spaces one doesn't "automatically" get that sound of half a century ago.

Quote:


All of the gear used today beats all of the gear used years ago in every way you care to assess gear. But the rooms have gotten much smaller, and a lack of proper acoustic treatment compounds the problem.



I entirely, thoroughly disagree. The way current digital gear offerings handle overs is entirely ungraceful and destroys the data thoroughly. Digital gear may offer certain kinds of fidelity or precision during "optimum use," but until it is implemented in a way that matches the kinds of quick decision-making and equipment adjustment that characterize certain active recording and mixing techniques, it doesn't integrate uniformly into many recording workflows. I think this may change with new products and a different design philosophy, but until then...

You can design a hand saw that makes the most incredibly precise cut when cutting strictly with the grain, but that totally destroys the piece of wood when used at a slight angle across grain. Is this a better saw? Sometimes we need to cut across the grain - the new hand saw is not the tool for all jobs.

-eliot bates
Title: Re: George....what's the resolution of analog?
Post by: oudplayer on May 17, 2004, 02:20:01 am
Brent wrote on Sun, 16 May 2004 19:44

I have listened to records from my youth, and remember them being much better than what they actually sound.  Granted CD's do sound different than records, and you don't get the words that you can read without a magnifying glass, the cool artwork, and the smell of vinyl. I don't know about you, but I gave up the Grado turntable long ago.  I enjoy pop free, rumble free, scratch free music.  What I like best is that I can get 10x in the peach crates. LOL


I have a good-sized collection of orchestral, Chinese, and Armenian music on 78s - the pops and rumble do not at all get in the way of my enjoyment of the music. And nothing made today sounds like it (with the exception of the 78s that the Cheap Suit Serenaders released a few years back). Not that they're the best sonics - obviously the dynamic range is, like, 10dB, and the frequency response... you can count it on one hand. But the effect of the recording focuses your attention on certain aspects of the music - the effect of modern CDs is entirely different.
Title: Re: George....what's the resolution of analog?
Post by: davidc on May 17, 2004, 04:09:59 am
oudplayer wrote on Mon, 17 May 2004 07:20

I have a good-sized collection of orchestral, Chinese, and Armenian music on 78s - the pops and rumble do not at all get in the way of my enjoyment of the music. And nothing made today sounds like it (with the exception of the 78s that the Cheap Suit Serenaders released a few years back). Not that they're the best sonics - obviously the dynamic range is, like, 10dB, and the frequency response... you can count it on one hand. But the effect of the recording focuses your attention on certain aspects of the music - the effect of modern CDs is entirely different.


I agree with you completely, oudplayer. It is not the resolution, or clarity that makes great music amazing to listen to. Do you think that higher resolution digital formats are any better in this regard?

I think that it is erroneous to think that analog tape has distortion (pleasing never the less), whilst digital is accurate. Digital has all kinds of distortions, that are not as well understood, and can have the effect of lowering the musical impact.

Best Regards

David C
Title: Re: George....what's the resolution of analog?
Post by: Nika Aldrich on May 17, 2004, 10:04:38 am
dwoz wrote on Sun, 16 May 2004 19:26

I don't agree that noise is a limiter of resolution.  I find that to be a red herring.  Of course noise is a factor, but as many others have noted, and as many including myself have heard time and time again, content can be discerned under the noise floor.


Yes.  The noise floor is not the bottom of hearing ability, but it marks the bottom.  Humans can hear generally about 20dB below the noise floor under ideal conditions, and mathematical proof has that amount limited to something like 30dB.  Thus, the level of noise is still the arbiting factor of dynamic range (what some choose to call "resolution") though the actual value is 20dB to 30dB lower than that, though heavily dependant upon signal content and other conditions (like the amplitude of the signal).

Quote:

Noise is never good, but noise floor isn't necessarily a boundary.


It marks the boundary and indicates where it is.


Quote:

also, I completely understand that a sample is an instant, without width...thus my "leading edge, middle, trailing edge" qualification of the "width" of a sample.  the sample represents a choice of a single value among perhaps many inside the span of time being represented by that sample.


No.  The sample represents the amplitude at an infinitely small moment in time which is at an equal distance from the last sample and the next sample.

Quote:

I stand by my assertion that sample rate has to do with quantization error...


You may stand by this but it is absolutely erroneous.  Sample rate has absolutely nothing to do with quantization error.  Ask about it and I will explain but I'm not sure what allows you to draw this assessment as of yet.

Quote:

as the more time between samples, the more opportunity to pick a value that doesn't represent the activity within the sample.


Totally lost on this phrase.  There is no "picking" of samples.  At the moment a sample is to be taken a sample is taken.  I don't get your phrase "activity within the sample?"

Quote:

And again, I stated that we only record the absolute value, not the slope, because we can interpolate slope using adjacent values, not having to resort to "complex" calculus and defining slope and value....as you state, after all, that because of nyquist, we don't see real values of slopes that diverge significantly from our ability to interpolate their values.


We don't see ANY values of slopes that diverge, because Nyquist's data is enough to completely reconstruct the waveform with 100% accuracy.

Trying to help - let me know where I'm breaking down in communication.

Nika.
Title: Re: George....what's the resolution of analog?
Post by: Nika Aldrich on May 17, 2004, 10:17:23 am
Jim Dugger wrote on Sun, 16 May 2004 21:35


May I ask Nika or one of the others here to help explain something to me in clearer (layman) terms?


I will try.

Quote:

It is true that the time and frequency domain are quite linked, correct?  Afterall, there are well known ways to covert information of one kind into the other.

So, does it stand that increasing the sampling rate is somehow (within some reasonable limits) equal to adding one bit to the frequency domain?


Yes.  This is correct.  Remember that the sampling process adds error (we call it "quantization error") to the signal at an amplitude that is determinable by the bit depth.  In a 1 bit signal the error amplitude is -6dBFS.  For a 16 bit signal it is -96dBFS, etc.  That noise level is, for the sake of this discussion, white noise covering the range between DC and Nyquist.  So let's take a 16 bit 48KS/s situation for starters.  We have a noise floor in there that exists at a level of -96dB and covers the range of OHz to 24KHz.  

If we increase the sample rate to 96KS/s then the noise is now -96dB from 0Hz to 48KHz.  We know that white noise is equal amplitude at all frequency bands, so half of the noise is present from 0Hz to 24KHz, and the other half of the noise there is present from 24KHz to 48KHz.  Half of the noise amplitude is equivalent to lowering the noise 3dB.  Since the broadband noise is -96dB, each half of the range only has noise at -99dBFS.  In otherwords, with a 16 bit 96KS/s signal the noise from 0Hz to 24KHz is -99dBFS and the noise from 24KHz to 48KHz is -99dBFS, and when you add the two together the total noise from 0Hz to 48KHz is -96dBFS (double the noise, add 3dB).  

Notice that when we doubled the sample rate from 48KS/s to 96KS/s the noise in the audible range lowered by 3dB even though the broadband noise level stayed at the same amount (-96dBFS).  This is how doubling the sample rate can effectively lower the audible noise.  It is not that doubling the sample rate lowers the total noise level, but it instead spreads it across a wider range so that the audible noise level is reduced.  If you double the sample rate twice then you increase the audible dynamic range by 6dB, or 1 bit's worth.  So going from 48KS/s to 192KS/s does, in theory, increase your dynamic range by 1 bit, but with today's converters this is mitigated in other ways.  Further, with 24 bit protocols it is irrelevant as the bit depth already exceeds the dynamic range we can hear.

Nika.
Title: Re: George....what's the resolution of analog?
Post by: ted nightshade on May 17, 2004, 11:31:28 am
Indeed some recordings from 45 years ago are things to stand in awe of.

I certainly do.

Bob Olhsson pointed out to me once that one of the main reasons why was that every attempt was made to procure a first generation master, straight from recording- the 3 track functioned as a safety if the engineer muffed the ride on the vocal.

What we have now is a mania for manipulation of the sound after recording it. Very different approach.

I'm very intrigued that probably the finest digital recording I've ever heard is a very early digital recording indeed- I think it's about 1984 and is a Decca recording of the Rite of Spring. I'm very intrigued to find that it is in many ways superior to any more recent digital recordings I can find! My guess is, that they created a first generation master directly from recording, and that's bit-identical to what's on the CD. That and some fantastic analog engineering on the front end.
Title: Re: George....what's the resolution of analog?
Post by: Jim Dugger on May 17, 2004, 11:40:06 am
Nika Aldrich wrote on Mon, 17 May 2004 09:17

So going from 48KS/s to 192KS/s does, in theory, increase your dynamic range by 1 bit, but with today's converters this is mitigated in other ways.  Further, with 24 bit protocols it is irrelevant as the bit depth already exceeds the dynamic range we can hear.


Thank you.  This is becoming clearer.

To summarize:

1.  We can decrease the amount of quantization noise (error?) by doubling the sampling rate or adding bits to the sample quantity.

2.  The value of doing this tails off quickly as we push the level of the noise a few db below that of the analog electronics on either side and the sampling rate at just a bit over double where the energy is we want to capture.




Title: Re: George....what's the resolution of analog?
Post by: Nika Aldrich on May 17, 2004, 11:53:16 am
Jim,

Close - see below:

Jim Dugger wrote on Mon, 17 May 2004 16:40


1.  We can decrease the amount of quantization noise (error?) by doubling the sampling rate or adding bits to the sample quantity.


Not quite.  We can decrease the amount of quantization error in a specific frequency band (such as the audible band) by doubling the sample rate.

Quote:

2.  The value of doing this tails off quickly as we push the level of the noise a few db below that of the analog electronics on either side and the sampling rate at just a bit over double where the energy is we want to capture.


Yes.  Add this to the fact that in current converters we do not allow the quantization error to manifest itself as white noise.  We use tricks to "reshape" it so that doubling the sample rate no longer affects the noise floor in the same way.  It is no longer an increase of 3dB per doubling of the sample frequency.  This, on top of the issues you raised above.

Nika.
Title: Re: George....what's the resolution of analog?
Post by: Ernie on May 17, 2004, 12:26:12 pm
Quote:

What this should tell you, is that there are some infinities that are bigger than others. How is that possible? Simple:

Take simple numbers. There are an infinte number of simple numbers, right? You start counting from one...and you can count onto infinity.

Now, take just the even numbers, and just count them exclusively. If you just count the even numbers...you can count them into infinity, right?

But when you compare the infinite numbers against the infinite even-only numbers, which is the greater infinity?

It's a brain-twister, right? Counter-intuitive as it is, it makes sense. Some infinities are indeed bigger than others.

Yes and no. Some infinities are bigger than others, yes; this is the math of transfinite numbers or infinite set theory as developed by Georg Cantor. But no, the infinity of "simple" (natural) numbers is not greater than that of even-only numbers. Transfinite numbers can only be compared by placing the systems in one-to-one correspondence; in the case of natural (whole) numbers v. even numbers, you can draw the following correspondence: 1 | 2, 2 | 4, 3 | 6, 4 | 8, 5 | 10, 6 | 12, 7 | 14, etc. endlessly. In terms of infinity, a part is equal to the whole; divide infinity and you still have infinity. This extends to all integers and fractional numbers; this infinite set is known as aleph-0 (represented with the Hebrew letter aleph).

However, there is no one-to-one correspondence between all rational numbers (all integers and fractional numbers as above) and all the points on a line, plane, or in a cube; this second set is therefore known as aleph-1. Curiously, the infinite set of points on a line one inch long and a line one lightyear long is mathematically equal (i.e., infinite and uncountable); and, more so, the number of points on a plane or in a cube is no greater than that on a line. Yet larger than the infinite set of points in a line, plane or cube is the set of all possible geometrical curves, or aleph-2. (c.f. Georg Cantor on infinite sets; one source: http://mathworld.wolfram.com/Infinity.html)

How or if this applies to analog v. digital recording, I leave to you lot; this is fascinating reading to your humble webmaster.
Title: Re: George....what's the resolution of analog?
Post by: Bob Olhsson on May 17, 2004, 03:27:16 pm
ted nightshade wrote on Mon, 17 May 2004 10:31

 I'm very intrigued to find that it is in many ways superior to any more recent digital recordings I can find! My guess is, that they created a first generation master directly from recording, and that's bit-identical to what's on the CD. That and some fantastic analog engineering on the front end.

Approach is indeed a lot of it. Unfortunately every approach to recording technology also interacts with the performers. What I see today is mostly the extremes. We either process the heck out of stuff or else people are refusing to do enough production to eliminate distractions. There's vintage this or that yet much of it is head-tripping instead of simply responding to what we hear.
Title: Re: George....what's the resolution of analog?
Post by: Ethan Winer on May 17, 2004, 04:58:59 pm
Steve,

> the only way that really matters is how it sounds <

Sure, no argument there. But please distinguish between "pleasing" and "accurate" because they're not necessarily the same. If you like the way something sounds and what you like is its inaccuracy, then that device can be considered an effect. As an extreme example, I like the way a fuzztone sounds but I sure wouldn't record all my tracks through one.

Some may like the sound of tape's compression and distortion, and that's fine. But I prefer the recording medium to simply reproduce exactly what I send to it. I'll add the effects myself separately. And the medium is really what we're discussing here, not U47 microphones or API consoles.

--Ethan
Title: Re: George....what's the resolution of analog?
Post by: Ethan Winer on May 17, 2004, 05:27:44 pm
Eliot,

> Working in those spaces one doesn't "automatically" get that sound of half a century ago. <

I never said it did. But the small rooms many people use today are a huge impediment to capturing a good sound and creating good mixes. If you put a great mike and a fabulous performer in a small room, it will still sound small. If you mix in a small untreated room you'll have a hard time hearing what you're doing, especially at the low end, and your mixes will suffer. An awful of lot of people seem to miss this basic fact, and that's all I was addressing.

> The way current digital gear offerings handle overs is entirely ungraceful <

Okay. But what's that have to do with the price of tea in China? Eventually people learn to use the tools and realize that with digital it's best to record at -10 instead of trying to slam the meter all the time. Or you patch a compressor into the recording chain and hit that instead of hitting the tape.

If someone prefers to work with analog that's fine with me. But to blame digital gear for not being more forgiving of user error is a little disingenuous, no?

--Ethan
Title: Re: George....what's the resolution of analog?
Post by: ted nightshade on May 17, 2004, 06:36:35 pm
Hey Ethan, here's the dilemma. Vocalist sings into the nicest mic I can get my hands on  (Manley Gold). Vibraphonist plays into same mic. Drummer plays into same mic. Record to the nicest digital I can get my hands on (Radar S-Nyquist), record to a modest but healthy and well-implemented analog machine (1968 Sony 854-4, 4 tracks, 1/4", 15 ips).

The analog machine sounds a whole hell of a lot more like the vocalist there in the room. This is distortion? It may represent distortion in some technical terms, from the output of one of the finest microphones around, but it sounds more like the source, by far, than a rather well-implemented and well-regarded digital machine. On any source you can name. In as fanatically purist acoustic aesthetic terms, not fuzzbox terms.

So what am I to make of that?

I'm thinking, the digital recording system needs to be a goodly bit better than a Radar S-Nyquist, to make a recording that resembles the source as much as the humble (OK, it was top of the line once) 35 year old analog machine. I imagine such things exist. I'd love to get ahold of one. I'm searching for digital converters than can make me a 2 track recording into a Masterlink that lets me breathe a sigh of relief and put away the damned splicing tape, razor blades, and head cleaner. I won't miss those things at all.

I'm not after distortion in any way. I'm after strict fidelity to the acoustic source in the room. I'd love to lose the little bit of noise, and I'd love to have something that sounded better than a healthy well-implemented analog tape machine.
Title: Re: George....what's the resolution of analog?
Post by: Jim Dugger on May 17, 2004, 08:21:46 pm
ted nightshade wrote on Mon, 17 May 2004 17:36

I'm thinking, the digital recording system needs to be a goodly bit better than a Radar S-Nyquist


I've always approached recording with the mindset the tools were like paintbrushes and canvas.

Ever notice how different a painting can be from the source that inspired it, and yet it is still an amazing, beautiful painting, as good as the source itself?

To me, live performance and recordings are a very different media.  And, as different media, there's a very high probability a best-of-class example from each might not be all that similiar.

Maybe that helps explain how you feel?

That said, I've got an early 80s Teac A3340 with Simul-sync around here I'll be happy to trade for that RADAR system.  It's in great condition, all original.
Title: Re: George....what's the resolution of analog?
Post by: ted nightshade on May 17, 2004, 09:09:33 pm
Jim Dugger wrote on Mon, 17 May 2004 17:21

ted nightshade wrote on Mon, 17 May 2004 17:36

I'm thinking, the digital recording system needs to be a goodly bit better than a Radar S-Nyquist


I've always approached recording with the mindset the tools were like paintbrushes and canvas.

Ever notice how different a painting can be from the source that inspired it, and yet it is still an amazing, beautiful painting, as good as the source itself?

To me, live performance and recordings are a very different media.  And, as different media, there's a very high probability a best-of-class example from each might not be all that similiar.

Maybe that helps explain how you feel?

That said, I've got an early 80s Teac A3340 with Simul-sync around here I'll be happy to trade for that RADAR system.  It's in great condition, all original.



I have high hopes for the RADAR system. I really liked what it was like to work with. I will be very interested to see how it develops in the future. I think my old Sony might smoke that Teac... you might feel different about a different tape machine. As it is, I wouldn't trade mine, although it cost me $500 and the RADAR system is at least 20 times that... and worth it I'm sure.

I know what you're saying, Jim, and I can appreciate that approach. In that case, it would be missing the point entirely to call the variation from the original "distortion"- "interpretation" would be more like it. I may yet get into that whole approach to things, but for now, my modus operandi is to create gorgeous sounds in real time in real space, and capture it onto some recording medium in a way that sheds maximum light on what it was like to be there, while sounding "like an album" (!) ...it's just that certain slices of life are more suitable for framing than others.

I just thought that it was especially ironic, in light of Ethan's "fuzzbox" comments, that deviation from a naturalistic depiction of the source was in fact not at all what lead me to prefer this analog machine to any digital I have had a chance to use so far.
Title: Re: George....what's the resolution of analog?
Post by: dayvel on May 17, 2004, 10:53:29 pm
I've never heard a recording in any medium on any playback system that sounded like the real thing. At best, a recording can only create an illusion which requires a certain "willing suspension of disbelief". To engineers who have spent a lifetime developing the mental filters which enable them to create the best possible illusion using analog means, a digital recording may never sound "right"; they just bring a different set expectations to the listening experience. A generation raised on digital sound is likely hear things quite differently. Neither is right or wrong, they're just different.

Dave Latchaw
Not an engineer - just a musician.
Title: Re: George....what's the resolution of analog?
Post by: Curve Dominant on May 18, 2004, 01:44:55 am
Quote:

posted by Ernie:
Quote:

What this should tell you, is that there are some infinities that are bigger than others. How is that possible? Simple:

Take simple numbers. There are an infinte number of simple numbers, right? You start counting from one...and you can count onto infinity.

Now, take just the even numbers, and just count them exclusively. If you just count the even numbers...you can count them into infinity, right?

But when you compare the infinite numbers against the infinite even-only numbers, which is the greater infinity?

It's a brain-twister, right? Counter-intuitive as it is, it makes sense. Some infinities are indeed bigger than others.


Yes and no. Some infinities are bigger than others, yes; this is the math of transfinite numbers or infinite set theory as developed by Georg Cantor. But no, the infinity of "simple" (natural) numbers is not greater than that of even-only numbers. Transfinite numbers can only be compared by placing the systems in one-to-one correspondence; in the case of natural (whole) numbers v. even numbers, you can draw the following correspondence: 1 | 2, 2 | 4, 3 | 6, 4 | 8, 5 | 10, 6 | 12, 7 | 14, etc. endlessly. In terms of infinity, a part is equal to the whole; divide infinity and you still have infinity. This extends to all integers and fractional numbers; this infinite set is known as aleph-0 (represented with the Hebrew letter aleph).

However, there is no one-to-one correspondence between all rational numbers (all integers and fractional numbers as above) and all the points on a line, plane, or in a cube; this second set is therefore known as aleph-1. Curiously, the infinite set of points on a line one inch long and a line one lightyear long is mathematically equal (i.e., infinite and uncountable); and, more so, the number of points on a plane or in a cube is no greater than that on a line. Yet larger than the infinite set of points in a line, plane or cube is the set of all possible geometrical curves, or aleph-2. (c.f. Georg Cantor on infinite sets; one source: http://mathworld.wolfram.com/Infinity.html)

How or if this applies to analog v. digital recording, I leave to you lot; this is fascinating reading to your humble webmaster.

------------------------------------------------------------ ------------
Ernie, PSW Webmaster



Ernie,

Thanks for putting a finer point to that, and I'm glad to see another Stephen Wolfram fan lurking.

How I felt this applied to analog vs. digital recording, was sensing this impression we seem to have that anaolg is somehow "infinite" in "resolution," and so by default digital is not...a hypothesis which always seemed flawed to me on an intuitive level.

Fortunately this conversation has since yielded some perspective in that regard.

Reverting back to my original post...the difference between Gaussian noise and TPDF noise, much agonized over by digital audio skeptics, always seemed to me a matter of parsing degrees of infiniteness (or otherwise).
Title: Re: George....what's the resolution of analog?
Post by: Ethan Winer on May 18, 2004, 11:17:49 am
Ted,

> The analog machine sounds a whole hell of a lot more like the vocalist there in the room. <

That sure has not been my experience! When I used to own a pro studio with a 2-inch recorder I could always hear the degradation between monitoring the console while recording and tape playback later. Today, with even a modest digital sound card (Delta 66), I hear no difference.

> I'm thinking, the digital recording system needs to be a goodly bit better than a Radar S-Nyquist <

I admit I'm not familiar with that box. But I'm curious: In what way does it sound different / worse than the direct mike feed from the console? Maybe it's simply broken or faulty?

--Ethan
Title: Re: George....what's the resolution of analog?
Post by: ted nightshade on May 18, 2004, 11:44:29 am
Ethan Winer wrote on Tue, 18 May 2004 08:17

Ted,

> The analog machine sounds a whole hell of a lot more like the vocalist there in the room. <

That sure has not been my experience! When I used to own a pro studio with a 2-inch recorder I could always hear the degradation between monitoring the console while recording and tape playback later. Today, with even a modest digital sound card (Delta 66), I hear no difference.



Hi Ethan- I'm not talking about the sound of the mc through the console- I'm talking about the sound of the vocalist live in the flesh through nothing but the air. That's what I'm trying to capture.

Quote:


> I'm thinking, the digital recording system needs to be a goodly bit better than a Radar S-Nyquist <

I admit I'm not familiar with that box. But I'm curious: In what way does it sound different / worse than the direct mike feed from the console? Maybe it's simply broken or faulty?

--Ethan


It's a very nice box as digital goes. Nothing broken about the one I used. FWIW, no console, just a Manley 40dB preamp- and what I find using the tape machine is, it sounds damn near exactly off the tape like it did monitoring through the tape machine in record pause with headphones.

I have no doubt that your experience is genuine, and that whatever 2" machine you were using didn't sound as good to you as what you have now- but implementation is everything. I'd heard a few pretty-good tape machines in the past and never got that excited about it- this one I have, I fell in love with immediately.

Plus, I never use more than a few tracks, because the degradation is too much for my taste. Same with digital though, although I've never used a digital mixer better than RME Totalmix, which is pretty nicely done and very simple like I like it.

From Dave:

Quote:

I've never heard a recording in any medium on any playback system that sounded like the real thing. At best, a recording can only create an illusion which requires a certain "willing suspension of disbelief".


I've heard awfully damn close- part of the trick is, you have to play it back at genuine performance levels. Which are huge! Excellent recordings through Bose 901s and 40,000 watts of custom ultra-clean dead-silent amps- I've heard amazing, very lifelike things. More than a few people coming in were fully expecting to find the band playing live in the room. The giveaway was, no band!

But yes, that's an extremely exceptional playback situation, and you are absolutely right about the willing suspension of disbelief. Although what is it that we are disbelieving exactly when we put on an vivid album or look at an amazing photograph? I suppose to think we're actually there would be a leap- the usual disbelief with an overdubbed recording is that the event ever actually took place all at once! Still, my goal is to get it so natural that absolutely as little as possible is between the listener and the music, on whatever system they have.

Quote:

To engineers who have spent a lifetime developing the mental filters which enable them to create the best possible illusion using analog means, a digital recording may never sound "right"; they just bring a different set expectations to the listening experience. A generation raised on digital sound is likely hear things quite differently. Neither is right or wrong, they're just different.


I was an adolescent when the first CDs came out. A few of my friends' folks had super spendy stereos and we used to lay around listening to these CDs in awe... things we knew from cassette and LP, but in some ways had never heard before. Other than cassette though, I don't think I ever heard reel-to-reel tape until I was in my 20's...

On the other hand my friend with the 40,000 watt stereo had his first reel to reel when he was 10, and he likes all kinds of analog tape anomalies that I really don't care for except as an effect. Nostalgia I'm not part of!

But these kids raised on mp3s and plastic computer speakers, blowing out their ears with ipods... yeah, they're gonna hear differently alright, and not any better either.

Title: Re: George....what's the resolution of analog?
Post by: Bill Mueller on May 18, 2004, 09:22:23 pm
Dave Latchaw
Not an engineer - just a musician.

"with a $10 horse and a $40 saddle
I started out punching them long horn cattle..."

my friends call me Ted Nightshade, but it says Edward Bruce Cowan on my birth certificate (only my dad calls me Edward)

Dear Dave, Ted and Edward

I'm a little confused here. Could you please be a little more specific. Please describe in detail the Sony analog recorder you are using. It is a consumer deck if I recall. Had a signal to noise of about 62 db at 15ips. Are you using noise reduction? Are you simul syncing with it to do overdubs? What kind of tape are you using? What bias levels are you using? At what record levels have your aligned the machine? What are the frequency response specs you are seeing through your system? Did you use the Radar on the same session as the Sony 854-4? Do you own the Radar? How many sessions did you do through the Radar if you don't own it.

If you have discovered a way to make a 1968 consumer 1/4" tape deck sound more realistic than Radar, I would sure like to know what it is. I have a Studer B67 that I will set up exactly the same.

You also made mention of a Pair of Bose 901's and 40k watts. I'm sure you are pulling our legs here but the 901's are not noted as studio monitors. I don't want to disparage Dr. Bose (I know him) but those are ancient speakers with enough IM (due to excessive speaker excursion) to raise the dead. How do those mixes translate to other listening environments?

Thanks for your insight.

BTW. If anyone is in the DC area this weekend, Bill Plummer and I are mixing the live broadcast for the HFestival on 99.1. It will be a great line up this year. I hope you enjoy the mixes.

Best Regards,

Bill
Title: Re: George....what's the resolution of analog?
Post by: charles maynes on May 18, 2004, 10:54:39 pm
I think it has been touched on here in this thread, but the thing I am really intrigued by is how certain analog recordings- mainly orchestral and non-rock recordings just totally leap out of your speakers and shout "I'M BAD"!

A great example I came across of this type of recording is the Polydor release (429 333-2) of Weill & Brecht's "Seven Deadly SIns & The Berlin Requiem. Unfortuately, there are no details to the recording in the liner notes but it does mention that the digital mastering was done by Dennis M. Drake of Polygram.


So anyway, the reason I bring this up is that a lot of people seem to think that analog is really kind of "low-fi" and that the "sound" of analog can be imparted via dsp- I think that the illusion of analog might be possible, but there seem to be an awful lot of variables that are still variable- IE the quality of the mag stock, which will certainly change through time, and even the contribution of processes such as Dolby SR, Which I personally think is a very nice treatment.

In the 192k thread I think GM mentioned that he was really more in the mode of discovery when dealing with the high sample rate options that have become available- as opposed to simply building an artificial barrier and saying that nothing can be better.... It is sort of like having a P-51 Mustang, enjoying it a lot, but then bad mouthing An F-18 Honet because it goes faster-


Thank Goodness there have been gentleman like Rupert Neve and Bill Putnam (Sr) who kind of were the banner wavers for High Quality audio gear way back when (and I most definitely place George M. there too!, though not quite so "back then")


Onward to better sound-

charles maynes
Title: Re: George....what's the resolution of analog?
Post by: Loco on May 18, 2004, 11:29:16 pm
charles maynes wrote on Tue, 18 May 2004 22:54

I think it has been touched on here in this thread, but the thing I am really intrigued by is how certain analog recordings- mainly orchestral and non-rock recordings just totally leap out of your speakers and shout "I'M BAD"!


It's not the arrow. It's the indian.
Title: Re: George....what's the resolution of analog?
Post by: ted nightshade on May 19, 2004, 01:33:17 am
Bill- I edited Dave's name out of the signature of that post- a cut and paste oversight! My words, not his. Sorry Dave!

The 901's weren't studio monitors- they were a blissful big as life playback system. The work was mixed and tracked on monitors of an obscure and small-time handmake, but they translate pretty well. My nutso friend who customized the four 10,000 watt amps for a playback pleasure type system actually had 901's installed in Paramount studios when he engineered there back in the 70's, and the mixes did not translate at all. It was a big expensive mistake. Not recommended for studio monitors, but a great approach that can sound more like instruments in a room than the usual front-facing speakers.

I can't tell you too much of the technical stuff on the Sony 4 track- it's 0 VU is higher than intended, it's bias is standard, and yes, it has about 65 dB of dynamic range. It's definitely noisier than the RADAR! I only demo'ed the RADAR S-Nyquist for a week, mostly worked at 44.1, and I did not put the two systems head to head, a great regret of mine- but I did record a lot of the same sources in the same room and got very, very different results, and much preferred the Sony in all cases, as sounding more like life. Vocals was the killer- I couldn't get the vocals to sound human on that RADAR, but no problem to tape. If I had nice compressors and EQ and all that it might be a different story. If I was a different Indian it might be a different story! But that RADAR has loomed large for me for a long time, mostly because it was such a joy to work with, workflow wise. Analog tape is definitely a big big hassle in comparison. I would way rather work with a RADAR, if only it sounded close to as good to me, on my usual sources in my usual spaces...

So take it with a grain of salt, as well you should. FWIW, that tape machine was selected as exceptional out of 5 selected back in the day from many more of the same kind. I may just be a sweetheart of a machine- I don't know, I've only used one other like it, and it was rebuilt after being shot with a shotgun during a drug-related murder back in the day in LA... <shudder> it was pretty sweet to, but had some issues with the bias getting stable.

Still, I'm hoping to find some digital that makes me forget about the whole tedious analog tape business... and I'll be glad when I do!
Title: Re: George....what's the resolution of analog?
Post by: Ethan Winer on May 19, 2004, 10:25:29 am
Ted,

> I'm talking about the sound of the vocalist live in the flesh through nothing but the air. That's what I'm trying to capture. <

Then like me, you're looking for a recording medium that most closely reproduces what you recorded. Which takes us back to my original statement that in all ways you care to assess it, digital recorders beats analog every time. If you have a digital system that doesn't sound exactly what you sent it, then it's broken. Or it should be replaced with a newer and better recorder that lives up to digital's potential, which is total transparency.

--Ethan
Title: Re: George....what's the resolution of analog?
Post by: ted nightshade on May 19, 2004, 01:51:18 pm
Hi Ethan- still trying to make this distinction:

Not what the mic picked up, but the sound that occurred in the room. To the extent that such a thing is possible.

I have to disagree strongly that all digital systems that aren't broken represent the source better than all analog systems. The reverse isn't true either, by any means. Some digital systems represent the source better than others, and some analog systems represent the source better than others. Some digital systems represent the source better than some analog systems, and some analog systems represent the source better than some digital systems. That much ought to be beyond dispute.

To best represent real acoustic sounds, you need the finest from either category, or at least very well implemented examples, which are exceptional to the categories as a whole.
Title: Re: George....what's the resolution of analog?
Post by: Duardo on May 19, 2004, 04:26:37 pm
Quote:

In what way does it sound different / worse than the direct mike feed from the console? Maybe it's simply broken or faulty?


I don't know how to describe the difference, but I've done several listening tests of different converters, and while those of us who were involved didn't necessarily agree on which converter sounded "better", we all agreed that the biggest difference was not between the different converters, but between any of the converters and the analog signal coming into the console.  The differences between the converters were surprisingly subtle, but it was fairly obvious when we were listening to the analog singal as opposed to the ones that had gone through a round of conversion.

-Duardo
Title: Re: George....what's the resolution of analog?
Post by: David Bock on May 19, 2004, 04:51:27 pm
"Everything important in audio that needs to be measured can be measured using currently available tools. These measurements can resolve to a level much finer/lower than anyone's ear can hear. There are no magical properties that we can hear, but which science has not yet identified. If you believe otherwise, I'd love to see some evidence.
--Ethan"
Wow. I'm glad that when the xray machine was invented, doctors didn't have your attitude and think they had it all figured out yet. Thankfully, humans have pursued further and discovered that they hadn't even yet imagined what it turned out that they needed to know. Remind me not to hire you for my R&D dep't.
True we have tools that can resolve things beyond what we can easily discern, I use some of those tools every day (one of them is even in a computer!). And I can measure and hear many of the changes I might make in a product.
But not all audible changes can be measured!
Unless of course you are from the Hirsch school of sound where all amplifiers sound the same, just the specs change.
For me, different amps can sound different yet have similar specs & even similar detailed measurements. Yet they sound different and no one can provide measurements to provide documentation for why the two amps might clearly sound different.......I'm surprised you've never experienced that.
regards,
David Bock

Title: Re: George....what's the resolution of analog?
Post by: Johnny B on May 19, 2004, 05:36:00 pm
That's funny about the amps. One of my best friends is a double E, and he always tells me that an amp is one of the most simple  devices anyone can ever build. He likes to say to me, "You can't hear any differences, here I'll prove it to you with this O-scope and some meters." But I reply, "You may be a really smart SOB, but you are tone deaf and you cannot "hear" with your damn "eyes."

I don't think there is much debate that amps sound very different from one another for a whole host of reasons that are beyond the scope of the thread.

But are double E's with large egos part of the bottleneck?

Far wiser people with better minds than me will have to answer that one.


Title: Re: George....what's the resolution of analog?
Post by: Nika Aldrich on May 19, 2004, 05:56:44 pm
dbock wrote on Wed, 19 May 2004 21:51

But not all audible changes can be measured!


Such as?

Title: Re: George....what's the resolution of analog?
Post by: Han S. on May 19, 2004, 07:05:00 pm
Ethan Winer wrote on Wed, 19 May 2004 15:25

Ted,

> I'm talking about the sound of the vocalist live in the flesh through nothing but the air. That's what I'm trying to capture. <

Then like me, you're looking for a recording medium that most closely reproduces what you recorded. Which takes us back to my original statement that in all ways you care to assess it, digital recorders beats analog every time. If you have a digital system that doesn't sound exactly what you sent it, then it's broken. Or it should be replaced with a newer and better recorder that lives up to digital's potential, which is total transparency.

--Ethan


Ethan, I don't have that experience. When I record a band or whatever and record it with my DDA-AMR board to a 2" machine and to a DAW like Nuendo or an MX2424, in my opinion the 2" machine sound more true to the source. So I'm afraid I'm with Ted.

If the Nuendo or whatever DAW sounded so exactly like the source, then what's the use of DSD?

Cheers, Han Swagerman.
Title: Re: George....what's the resolution of analog?
Post by: hargerst on May 19, 2004, 09:49:22 pm
Nika Aldrich wrote on Wed, 19 May 2004 16:56

dbock wrote on Wed, 19 May 2004 21:51

But not all audible changes can be measured!


Such as?


I remember back when transistor amplifiers started appearing on the market.  Many of us heard differences between tube amps and transistor amps that measured "exactly the same".  Turned out we had to learn how to measure things differently, and we came up with TIM, slew rates, problems with massive amounts of negative feedback, and the actual individual harmonics that were distorting (instead of THD).  

Seems our ears were right.

Makes me wonder if changing them fast rising squares to a whole bunch of itty bitty ramping sine waves might be messing with the slew rate a bit.  

Ya reckon?
Title: Re: George....what's the resolution of analog?
Post by: Brent Handy on May 19, 2004, 10:41:47 pm
Read:

Coding for High Resolution Audio Systems by J. Stuart
Audio Analog to Digital Convertors by Mike Story

Order from AES.

Sorta quoting:

Analog domain: signals are continuous in voltage, infinate resolution and are continuous in time.  Digital domain: needs representation, samples, that have finite resolution (fixed number of bits) and are discrete in time. Samples are spaced evenly in time.

Title: Re: George....what's the resolution of analog?
Post by: Curve Dominant on May 19, 2004, 10:58:13 pm
Quote:

posted by Harvey Gerst:
Makes me wonder if changing them fast rising squares to a whole bunch of itty bitty ramping sine waves might be messing with the slew rate a bit.

Ya reckon?



Harvey,

I'm stumped. Please enlighten.

How does A-D conversion affect slew?
Title: Re: George....what's the resolution of analog?
Post by: hargerst on May 19, 2004, 11:36:41 pm
Eric Vincent wrote on Wed, 19 May 2004 21:58

Quote:

posted by Harvey Gerst:
Makes me wonder if changing them fast rising squares to a whole bunch of itty bitty ramping sine waves might be messing with the slew rate a bit.

Ya reckon?



Harvey,

I'm stumped. Please enlighten.

How does A-D conversion affect slew?


I think we're all agreed that a 7.4kHz square wave (kinda looks like the side of a building) comes out as a sine wave (kinda looks like a ski slope). One of the main things that's changed is the rise time, isn't it?

Call it slew rate, call it skew rate, call it rise time, but it ain't goin up as fast as it was.  I don't know what to call it, but when something comes out different from when it went in (and it's down low enough to hear), what would you call it?

Granted, I'm an old fart and I don't understand a lot of this digital stuff, but it seems logical to me that there is a difference between something that goes up like this: | and something that goes up like this: / - my only question is: at 7.4kHz, is it audible to some people?
Title: Re: George....what's the resolution of analog?
Post by: Zoesch on May 20, 2004, 12:14:02 am
hargerst wrote on Thu, 20 May 2004 11:49

I remember back when transistor amplifiers started appearing on the market.  Many of us heard differences between tube amps and transistor amps that measured "exactly the same".  Turned out we had to learn how to measure things differently, and we came up with TIM, slew rates, problems with massive amounts of negative feedback, and the actual individual harmonics that were distorting (instead of THD).  

Seems our ears were right.

Makes me wonder if changing them fast rising squares to a whole bunch of itty bitty ramping sine waves might be messing with the slew rate a bit.  

Ya reckon?



Not really but you're bound by the THF, topology, slew rate, frequency response and phase response of the reconstruction filter.

Discussing the performance of your DAC without discussing these (And other aspects like the anti-imaging filter, clocking, etc.) filter is pretty useless.
Title: Re: George....what's the resolution of analog?
Post by: Zoesch on May 20, 2004, 12:49:11 am
Harvey, seeing your clarification...

Mixed bag answer... Theoretically, no, the slew rate of the signal shoud remain unchanged as long as it's well within the frequency range of the converter.

In reality, yes, but not because the conversion process in itself introduces any changes, but simply because the reconstruction filter is subject to the same constraints as any other gyrator system
Title: Re: George....what's the resolution of analog?
Post by: Curve Dominant on May 20, 2004, 01:09:50 am
Quote:

posted by Harvey Gerst:
I think we're all agreed that a 7.4kHz square wave (kinda looks like the side of a building) comes out as a sine wave (kinda looks like a ski slope). One of the main things that's changed is the rise time, isn't it?


Harvey,

I dunno about that, without actually seeing that wave. Perhaps the part of that square wave which seems to have "gone missing" is simply information which is above the Nyquist limit. We wouldn't hear it, so it isn't represented (assuming your square wave is indeed including post-20Khz harmonics and that's what's missing from it).

"Rise time" is a factor in analog gear, mainly amps, right? The time it takes for the amp to respond to the incoming signal?

We cannot really transfer that sort of phenomenon to digital audio conversion quite the way you seem to be interpreting it. Perhaps the more expert minds can clarify this point.

Quote:

Call it slew rate, call it skew rate, call it rise time, but it ain't goin up as fast as it was. I don't know what to call it, but when something comes out different from when it went in (and it's down low enough to hear), what would you call it?


I would call it filtering out redundant information.

Quote:

Granted, I'm an old fart and I don't understand a lot of this digital stuff, but it seems logical to me that there is a difference between something that goes up like this: | and something that goes up like this: / - my only question is: at 7.4kHz, is it audible to some people?


I'm a semi-old fart, and I struggle to semi-understand it myself sometimes. In between writing and recording and cooking and shagging my girl (not necessarily in that order), I spend some time studying this stuff. Let's say that at this point, I semi-understand it. And my semi-understanding leads me to believe that seeing "|" going in and seeing "/" on the screen doesn't mean anything audible, let alone meaningful, has been lost. It simply means the computer screen is not showing me the whole picture, but rather the semi-whole picture. Which is semi-fine for my needs.

Does that semi-answer your question?
Title: Re: George....what's the resolution of analog?
Post by: Han S. on May 20, 2004, 06:40:47 am
In a dutch pro audio magazine there was a test with an Ampex ATR102 and a DAW. They recorded a 15khz square wave on both and in playback the ATR showed an almost perfect square wave while the DAW showed a kind of between square and a sinus on the scope.

I guess this phenomenon is what Harvey is pointing at. Most people can hear the difference between a square wave and a sinus.
Title: Re: George....what's the resolution of analog?
Post by: George Massenburg on May 20, 2004, 07:06:18 am
Han S. wrote on Thu, 20 May 2004 05:40

In a dutch pro audio magazine there was a test with an Ampex ATR102 and a DAW. They recorded a 15khz square wave on both and in playback the ATR showed an almost perfect square wave while the DAW showed a kind of between square and a sinus on the scope.

I guess this phenomenon is what Harvey is pointing at. Most people can hear the difference between a square wave and a sinus.


Well, yes.  But not at 15kHz.  Not unless there's something else wrong (like non-linearities).

GM
Title: Re: George....what's the resolution of analog?
Post by: Curve Dominant on May 20, 2004, 09:21:03 am
Quote:

posted by Han S:
In a dutch pro audio magazine there was a test with an Ampex ATR102 and a DAW. They recorded a 15khz square wave on both and in playback the ATR showed an almost perfect square wave while the DAW showed a kind of between square and a sinus on the scope.

I guess this phenomenon is what Harvey is pointing at. Most people can hear the difference between a square wave and a sinus.



That's right, most people WOULD hear the difference if the DAW was deleting so much information as that "test" had you believe.

So why do you think people would NOT hear a difference??
Title: Re: George....what's the resolution of analog?
Post by: Nika Aldrich on May 20, 2004, 09:42:32 am
hargerst wrote on Thu, 20 May 2004 02:49

Nika Aldrich wrote on Wed, 19 May 2004 16:56

dbock wrote on Wed, 19 May 2004 21:51

But not all audible changes can be measured!


Such as?


I remember back when transistor amplifiers started appearing on the market.  Many of us heard differences between tube amps and transistor amps that measured "exactly the same".  Turned out we had to learn how to measure things differently, and we came up with TIM, slew rates, problems with massive amounts of negative feedback, and the actual individual harmonics that were distorting (instead of THD).  

Seems our ears were right.

Makes me wonder if changing them fast rising squares to a whole bunch of itty bitty ramping sine waves might be messing with the slew rate a bit.  

Ya reckon?



No.  It's a pretty complex topic, though.

I'm still waiting for those differences that the ear can hear that are completely unmeasurable.

Nika.
Title: Re: George....what's the resolution of analog?
Post by: Level on May 20, 2004, 10:12:57 am
The audiophile cable rants that litter the Internet are a fine example of a majority of people hearing a difference in one cable over another but when took to task by the "lab heads" they have "not figured out what to measure to substantiate to perceived difference"

All too often, a group of people will agree on an audible difference and the technicians agree there are no measurable differences. In this, what is really happening that alters the sound should be investigated with a much more open mind that a preconceived set of parameters. If such were not the case (as often displayed) Tesla would have been totally discounted and we would most likely be running on DC power grids.(!) After all, Edison himself was a huge naysayer of alternating current.

In audio, many examples of audible differences that are not "proven" by current measurement techniques. Especially true when a majority can hear the differences and agree upon what they hear.

Title: Re: George....what's the resolution of analog?
Post by: Nika Aldrich on May 20, 2004, 10:17:13 am
hargerst wrote on Thu, 20 May 2004 04:36

I think we're all agreed that a 7.4kHz square wave (kinda looks like the side of a building) comes out as a sine wave (kinda looks like a ski slope). One of the main things that's changed is the rise time, isn't it?


Actually, what has changed is the addition of high frequency content that, when added to the waveform in a certain way, causes the steeper sides.  It is the addition of the higher frequency content that we are interested in.  

Quote:

Call it slew rate, call it skew rate, call it rise time, but it ain't goin up as fast as it was.  I don't know what to call it, but when something comes out different from when it went in (and it's down low enough to hear), what would you call it?


In this case we call it a change in frequency content.  When talking about the insufficiencies of certain analog equipment we might say that the limiting factor is the slew rate, but the way in which that manifests itself is in a change in frequency content.  We can save a step here and simply look at the change in frequency content.  The change in slew rate is always spoken of as a cause, not the effect.  In the case of digital audio the cause is the filters in the A/D and the effect is a reduction in frequencies.  

Quote:

Granted, I'm an old fart and I don't understand a lot of this digital stuff, but it seems logical to me that ...



Digital audio is perpetually non-intuitive.  

Nika.
Title: Re: George....what's the resolution of analog?
Post by: hargerst on May 20, 2004, 10:21:46 am
George Massenburg wrote on Thu, 20 May 2004 06:06

Han S. wrote on Thu, 20 May 2004 05:40

In a dutch pro audio magazine there was a test with an Ampex ATR102 and a DAW. They recorded a 15khz square wave on both and in playback the ATR showed an almost perfect square wave while the DAW showed a kind of between square and a sinus on the scope.

I guess this phenomenon is what Harvey is pointing at. Most people can hear the difference between a square wave and a sinus.


Well, yes.  But not at 15kHz.  Not unless there's something else wrong (like non-linearities).

GM

Well, I've been asking about what happens around 7.4kHz, where we know for sure (dont we?) that a 22.05 low-pass filter would cut off all the harmonics of a 7.4kHz square wave, leaving just a 7.4kHz sine wave. And even lower in frequency (around 4kHz), a square wave (going in) might only have a single harmonic present in the output, and does that resultant waveform sound like a square wave?

I know a lot of preamp designers call for linearity out to 100 and 200kHz, and beyond.  If I'm understanding Nyquist correctly, then it seems like a steep cutoff frequency beyond 22.05kHz in preamps also should have no audible effect on the sound, even in the analog realm.  If you could rig a steep 22.05kHz low pass filter at the output of a preamp, and switch it in and out, would you hear a difference - any difference at all?

Damn, I really wish I knew more about this stuff.  I know intuition and common sense aren't always right when it comes to this digital design stuff, and since I don't have much of either of those commodities these days, I hafta wonder out loud in forums like this, making me look even stupider.

Title: Re: George....what's the resolution of analog?
Post by: Nika Aldrich on May 20, 2004, 10:22:09 am
Level wrote on Thu, 20 May 2004 15:12

The audiophile cable rants that litter the Internet are a fine example of ...


... an interesting psychological experiment.  Please supply any (and I mean any) properly conducted cable tests that determine the audibility of the various things that these people speak about other than heresay.  Any.  1 properly conducted study.  This is a VERY poor choice of sources to discredit science.  

Quote:

a majority of people hearing a difference in one cable over another but when took to task by the "lab heads" they have "not figured out what to measure to substantiate to perceived difference"


The first challenge is to substantiate that there WAS an audible difference.  Let's get that nailed down first?

Quote:

In audio, many examples of audible differences that are not "proven" by current measurement techniques. Especially true when a majority can hear the differences and agree upon what they hear.




I'm game.  Show me.

A single study.

One.

Nika.
Title: Re: George....what's the resolution of analog?
Post by: Johnny B on May 20, 2004, 01:03:22 pm
Harvey,

You described how minds were opened and new measurement techniques were the result. Can you give more details on how that process occurred? The arguments that were going on back then and how they came up with the new test procedures? Ya know, more details. Thanks.
Title: Re: George....what's the resolution of analog?
Post by: Level on May 20, 2004, 01:15:19 pm
Here you go Nick, I will start with this one...but the formal studies, I have to dig back in my archives. Their are just too many to choose from.

Read the entire thread and the links if you want to tread those waters.

Also, remember, a cable is part of a CIRCUIT. The associate equipment will provide different results on the same cable.

  http://www.audioasylum.com/scripts/t.pl?f=prophead&m=844 1
Title: Re: George....what's the resolution of analog?
Post by: Nika Aldrich on May 20, 2004, 02:59:06 pm
Level wrote on Thu, 20 May 2004 18:15

Also, remember, a cable is part of a CIRCUIT. The associate equipment will provide different results on the same cable.


So the cable then is irrelevant?

Nika.
Title: Re: George....what's the resolution of analog?
Post by: Nika Aldrich on May 20, 2004, 03:15:32 pm
Level wrote on Thu, 20 May 2004 18:15

Here you go Nick, I will start with this one...but the formal studies, I have to dig back in my archives.


You'll have to dig back into your archives.  This looks like a bunch of banter amongst EEs about whether or not the math is valid.  I was asking for ABX testing of the differences between different exotic cables that you insist are audible.  Please provide evidence.

Interesting reading, though.  Seems like the same type of stuff that goes on here - various people bringing forth attempts to rationalize something and others trying to explain why their caveats are inapplicable.  

Nika.
Title: Re: George....what's the resolution of analog?
Post by: hargerst on May 20, 2004, 05:11:27 pm
Johnny B wrote on Thu, 20 May 2004 12:03

Harvey,

You described how minds were opened and new measurement techniques were the result. Can you give more details on how that process occurred? The arguments that were going on back then and how they came up with the new test procedures? Ya know, more details. Thanks.


PRocess?  Actually it was just two camps arguing: the engineers who designed the stuff, and the engineers who used it in the studios.

The engineers who designed the stuff swore there was no measurable difference between the transistor stuff and the tube stuff.  Same frequency response, same THD, same IM - all tested identical using the standard swept sinewave testing that was the standard.  But the engineers that used the stuff also swore there was a big unexplained difference in the actual sound.  

After a year or so of back and forth squabbling, an engineer from one of the camps discovered that sine waves weren't showing up how amplifiers responded to "sharper" waves (i.e., transients).  

All of a sudden, new terms started popping up: TIM (Transient Intermodulation Distortion), Slew Rate, time smear, caused by massive amounts of negative feedback, and a host of other terms.

Out of all this, improved testing and a better understanding of measurements occured, but it was very rough for about a year or two while user engineers tried to convince design engineers that the current testing procedures were missing something significant.
Title: Re: George....what's the resolution of analog?
Post by: Level on May 20, 2004, 05:40:11 pm
Being part of a circuit makes the cable very relevant. How did you come up with that? Anything in the circuit path affects other thngs, loads, etc.

If cables were irrelevant, George could take his loudspeaker cables off and replace them with Wal-Mart 2.99 spool of 24/2. I really think this is the fartherest thing from his mind.
Title: Re: George....what's the resolution of analog?
Post by: Nika Aldrich on May 20, 2004, 05:47:44 pm
No question that cable is relevant to a certain degree.  There are several very valid characteristics of cable that need to be taken into regard.  The issue is the esoteric extremes that marketing manufacturers use about cables that audiophiles tend to bicker about.  The bickering, itself, becomes the news story and tends to give credence to itself, not the differences between the cables.

The same is true here.  The bickering about sample frequencies becomes noteworthy so it is implied that differences inherently exist - as was your argument.  I'm afraid it isn't that simple - with cables or with sample frequencies.  

Cables can make a difference to a point.  After that point they don't, and I thought that is what you - and all these knuckleheads in the audiophile industry - were referring to.,

Nika.
Title: Re: George....what's the resolution of analog?
Post by: Johnny B on May 20, 2004, 11:47:09 pm
Thanks Harvey. That was helpful!

Sounds a little like the current debate, does it not?
Title: Re: George....what's the resolution of analog?
Post by: josh on May 21, 2004, 12:31:49 pm
Regarding the issue about analog recording sounding more like the live performance in the room vs. some digital recording, not counting the accuracy of the actual recording, there is something critical being left out:  perception.

For example, I noticed when I first saw the film "Jurassic Park" that the dinosaurs looked alarmingly realistic.  However, if you put in the DVD and pause it and look at one frame, they do not look realistic at all.  What's the difference?  Well of course the difference is that the motion and sound of the animals on the screen gives us sensory cues that allows our minds to ignore the not-so-real image quality and interpret it as a perhaps-real event.  Lacking the motion and sound, it is not nearly as realistic looking.  Filmmakers have known for years that you can stimulate a sense of reality in a film by distracting our senses away from what lacks detail and accuracy and thereby masking the inaccuracy.  In the same way magicians and illusionists use distraction to convince us that we see things we don't.  I suspect analog tape does something similar.

What all this does is illustrate that what we percieve of a live performance where we have a combination of sensory input other than just auditory is not necessarily a good measure of what it actually sounds like in the absense of the other sensory input.  For example, if I put on a pair of binaural mics affixed to my ears, go into a noisy restaurant and record a hushed conversation with my friend, I can certainly hear and understand the conversation just fine when I am there, but in all liklihood if I play back the binaural recording, it will be completely unintelligible.  The ability of my mind to filter out ambient noises and focus on the sound of a source that I can see and an focused on visually acts sort of an automatic internal "mixdown" that amplifies whatever sound in the mix I want simply by my focusing attention on it.

So...  if we think analog recording sounds more like the actual live event in the room, and we can measure that the analog recording is actually not as accurate in terms of dynamics, distortion, whatever, then we could possibly conclude that somehow the distortions inherent to the analog recording in some way help along our ability to perceive that it's a real event in the absense of the other sensory input that we would have in a real event.  In this case then it is very possible that more accurate recordings do not necessarily sound more realistic.  

In my binaural recording example above, my headworn microphones capture a relatively accurate representation of the sound field present at my ears, so if I play it back in headphones, from an accuracy perspective, it is pretty accurate representation of the event that happened.  However, to make it sound more realistic, in other words, to make it possible to understand the conversation as I understood it when it was happening, then I would need to actually put a third mic on the speaker, pan it to center, compress it and crank it up in the mix.  This is intentional distortion, it would be making for a much less "accurate" playback of the original sound field, but from a human perception point of view, it would sound more "real" because in the real event, I could understand the conversation, and in the recording I cannot, because I don't have the help of my eyes and brain to focus my attention on the speaker, so I must focus my attention on the speaker solely with auditory cues, which in this case include increased amplitude and compression to bring up lower level detail.

This is the whole reason why we close-mic anything making recordings, why we select hyped microphones and preamplifiers, why we use compression and EQ, why we aggressively pan things off-center if we don't want them to be the center of attention, etc.  The whole playback of most musical events we have recorded is loaded with very intentional distortion and inaccuracy that we (most recording engineers) have judged is necessary in order to convey a sense of realism in the absence of our other sensory input.

This may be why Ethan's opinion may be different from that of someone recording a dense rock mix.  If you record a solo piano in a quiet environment, clearly it is not necessary for you to manipulate that sound any to focus the listener's attention on it.  There's nothing to compete in the mix.  A very accurate recording will do the job.  But to get a rock vocalist to be intelligible and up-front in the mix while not overpowering other instruments requires very intentional distortion of the real event.  A binaural recording won't work at all...  the vocalist will get masked into the background noise and you'll drive the listener nuts trying to hear the lyric.  In this sense, analog tape imparts some degree of the type of distortion that helps with this, and may even be sufficient without further processing, so some can conclude that "analog sounds more real", and perhaps by itself in certain types of recordings, without other processing, it does, but this is is impossible to measure beyond an opinion poll.

I tend to side with Ethan in that, for me, I'd rather have it accurately recorded, and then I can process it as I choose in order to make a realistic sounding recording.  But I don't confuse "accurate" and "realistic" because they are simply not the same thing.  "Realistic" sound involves a lot of factors that are not related to accuracy, but related to the way people interpret sound, the playback medium & system, etc.  However I can see the point of people for whom their analog equipment gets it more "realistic" sounding for the type of music and recordings they are making without having to apply (as much) additional processing.  However, it makes no sense to argue that just because you percieve it to be more "realistic" that it is more "accurate".  Again to my point about Jurassic Park...  a still image of a dinosaur can be made that is far more accurate (in terms of resolution etc.) than any in that film, but the fact that it is not moving and accompanied by sound means that you won't jump out of your seat the way you will in the movie theater with the much duller representation.  Less accurate, but providing more sensory input or sensory input that stimulates our mind to interpret something as realistic, appears to be more realistic than a strictly more accurate representation in the absense of such cues.

Does this make sense to anyone?  Feels like I'm rambling.  I know what I'm trying to say and I get the feeling maybe nobody else will.
Title: Re: George....what's the resolution of analog?
Post by: magicchord on May 22, 2004, 04:26:07 pm
Y'know, Josh, you just might have something there.

Patrick Bryant
MagicChord Music
my avatar is an actual picture of me
Title: Re: George....what's the resolution of analog?
Post by: djui5 on May 23, 2004, 07:24:23 am
I have a quick question.

I've read through this whole thread and didn't see anyone reply with some test results of analog equipment. Not analog tape...but outboard gear, tape machines, that kind of thing.

Has anyone done testing to verify the limitations of this type of thing? Or can someone point me to reading material of someone who has? By limitations I'm refering to freq response and noise floors.

I think this is more along the lines of what Jazzius was asking in the first place.


Title: Re: George....what's the resolution of analog?
Post by: chrisj on May 23, 2004, 07:05:56 pm
FWIW, I measured the noise floor of analog vinyl records in the same way that I measure dither and noise shaper outputs, once.
http://www.airwindows.com/analysis/VinylNoise.html
Quick precis- I recorded vinyl output to 24 bit, choosing as the highest signal level a brutal 8 cm/sec modulation off a Stereo Review test record (an IM test- was a bit dirty but not in fact horribly distorted) and the silent groove on the same record as the noise floor sample. I edited them together and normalized them and did an FFT analysis on them.
Upshot- around 2-3K it was upwards of 100 db s/n relative to the IM test peaks. There was noise at around 4.5K that probably wound up around -90 if you count every little spike. Under 1K, it's clearly worse than 100 db s/n, and it's probably much worse than that under 100 hz, which goes neatly off the chart in almost exponential fashion (no rumble filter is employed, and the preamp goes quite low regardless). Over 10K, you tend to get better than 120 db s/n ratio. It's very, very frequency dependent.
It was a fun experiment Smile
Title: Re: George....what's the resolution of analog?
Post by: jfrigo on May 24, 2004, 07:13:00 am
George Massenburg wrote on Sun, 16 May 2004 10:58


Thanks very much for your notes.  Now, this is alot closer to the discussion that I think  we should be having about digital audio.  I'm currently having a enlightening discussion off-line with Jim Johnston about quantizing multi-channel audio and differential resolution in the time-domain.

George


I would love to hear some of that discussion. Jim Johnston is definitely the man to talk to about such things. I had a brief email from him on the subject some years ago and would love to hear more detail and more recent thoughts.

As for infinite resolution in analog, of course not. On tape there's a finite number of little particles to be magnetized, a finite number of domains, and analog electronics certainly have plenty of limitations in dynamic range, signal to noise ratio, frequency response, and many distortions. Infinite resolution and infinite energy go hand in hand an are similarly impossible.

We may often like the color of analog better, but it's accuracy is not likely the attraction.

Title: Re: George....what's the resolution of analog?
Post by: George Massenburg on May 24, 2004, 10:22:28 am
Jay,

Couldn't agree more.

All too often we see a pretty good try at an objective listening test, one where a difference is revealed.  Inevitably, a conclusion is drawn after the choices are revealed.  

Such is the case with the current "In The Box" mixing tests.  I've had any number of otherwise rational guys tell me what's better about breaking out the digital sources and mixing analog, but the tests, and the conclusions, are invariably tilted toward the analog case.

It's just the hardest thing to be objective...

George
Title: Re: George....what's the resolution of analog?
Post by: Tojo on May 24, 2004, 04:24:22 pm
the tests, and the conclusions, are invariably tilted toward the analog case.



?? How so? Is this a typo?
Title: Re: George....what's the resolution of analog?
Post by: George Massenburg on May 25, 2004, 02:46:21 am
No, that's no typo.

Most of the "scientific" comparisons I hear about amount to...

"O.K. I take the output of ProTools into my SSL console, and I listened to a 2-channel mix out of ProTools and then I brought up individual tracks into the console and it sounded much, much better.  Everybody in the room could hear it!"

NO calibration. NO A/B.  NO objectivity.

I'd have to call that "biased" towards analog.

George
Title: Re: George....what's the resolution of analog?
Post by: Tojo on May 25, 2004, 03:15:32 am
Sorry, I was confused. Somehow I thought you were referring tests from JJ Johnston.
Reading the thread too quickly, I guess.

It's true that most people who tally data these days seem unacquainted with sample selection for proper experimental design and also seem mostly ignorant of analysis of variance and factor analysis.
Title: Re: George....what's the resolution of analog?
Post by: Ethan Winer on May 25, 2004, 11:14:24 am
Folks,

Sorry for the delay, I was at the big Home Entertainment Show in New York most of last week. Man, talk about your pseudo-science. It seemed like every other booth was selling expensive wire of one sort or another. A few even used the word "magic" in their claims. Worse than the overpriced cable sellers were those pushing expensive isolation devices for preamps, DVD players, and other electronics that are not affected by vibration. Yikes.

I saw several posts here refer to slew rate incorrectly. Slew rate limiting is a form of distortion, and it can be easily measured using standard test gear available since the 1950s. The notion that engineers were unable to test for problems caused by slew rate limiting until recently is wrong.

More to the point, a filter that rolls off above a certain frequency does change the slope of the waveform, but it does so linearly and without distortion. Slew rate limiting occurs when an output stage cannot provide enough current, and the result is decidedly nonlinear. This nonlinearity merely creates harmonic and IM distortion as does any other nonlinearity.

--Ethan
Title: Re: George....what's the resolution of analog?
Post by: Brent Handy on May 25, 2004, 01:00:44 pm
Anyone remember AES about 89 or so?  Some guy had a black box and a switch.  He had some high-end hi-fi cable and belden plain jane install solid-copper.  The wire was mis-labeled.  In a blind test, with headphones on, while on the noisy floor, people chose the belden, thinking it was the new cable they were told about.
Title: Re: George....what's the resolution of analog?
Post by: Loco on May 25, 2004, 01:24:06 pm
George Massenburg wrote on Tue, 25 May 2004 02:46

NO calibration. NO A/B.  NO objectivity.

I'd have to call that "biased" towards analog.


Even when I tried to be biased towards analog, I couldn't make it happen.

A while ago with a friend of mine, we tried a couple of mixing boxes (call them DAW analog front ends) to see if we could convince the studio owner to buy a box. We recalled a mix on a DMX-R100 and made 8 stems to be routed to the boxes. The Manley box lost the stereo image just a hair lacking some definition on the high end that the original DMX mix had. The Cranesong one presented a challenge trying to pan some stuff exactly as in the DMX mix, and presented the same high end thing we saw in the Manley, although at a lower frequency. Too bad we couldn't get ahold of a GML 9100....

We tried anyway to get convinced the studio owner, so we set the blind test matching levels very close. In the room there were the owner, 2 engineers, 3 assistants and the studio manager. All of them preferred at the first try the DMX mix.

It's not that those boxes are bad. They sound good. Maybe it's just they don't sound all that money. You can improve your sound a lot more putting your money somewhere else.
Title: Re: George....what's the resolution of analog?
Post by: St. Domingo's on May 25, 2004, 04:06:37 pm
Quote:

DVD players, and other electronics that are not affected by vibration.


Ethan, please help this bear of little brain out.

Are you saying that DVD players are NOT affected by vibration?

One would assume anything that could cause eccentricity in disc rotation would affect the performance of a DVD player in the same way it can in a CD player.  Where am I going wrong?

Cheers,

Matt
Title: Re: George....what's the resolution of analog?
Post by: RMoore on May 25, 2004, 04:49:33 pm
FWIW - I bought some of the Lynn Fuston (sp?) CDS & thought on 1st listening that the PT in the box mix was  the one I preferred / the non box mix..

And upon knowing which was which - somehow suddenly the analogue mix seemed to be the one with 'vibe' and the PT box mix was plasticky..
Title: Re: George....what's the resolution of analog?
Post by: George Massenburg on May 25, 2004, 10:13:41 pm
Ryan Moore wrote on Tue, 25 May 2004 15:49

FWIW - I bought some of the Lynn Fuston (sp?) CDS & thought on 1st listening that the PT in the box mix was  the one I preferred / the non box mix..

And upon knowing which was which - somehow suddenly the analogue mix seemed to be the one with 'vibe' and the PT box mix was plasticky..


THANK YOU.

And this is why in-the-box is losing to analog mixing...because it supposedly "vibier", even though it doesn't sound as good.  Definitely a case of the "King's New Clothes"

But if you go only by ear and not by fear of being shamed, most of the time you're really not going to like what all the extra fucked-up analog electronics are doing to your music.

George
Title: Re: George....what's the resolution of analog?
Post by: djui5 on May 26, 2004, 03:10:03 am
George Massenburg wrote on Tue, 25 May 2004 20:13
But if you go [i

only[/i] by ear and not by fear of being shamed, most of the time you're really not going to like what all the extra fucked-up analog electronics are doing to your music.

George



I've long thought that this is the reason why a lot of people "don't like" digital. It exposes aspects of audio that previously haven't been heard.

I think it calls for a new method of working....you have a clean plate....a new canvas if you will.

Title: Re: George....what's the resolution of analog?
Post by: davidc on May 26, 2004, 03:53:55 am
George Massenburg wrote on Wed, 26 May 2004 03:13

Ryan Moore wrote on Tue, 25 May 2004 15:49

FWIW - I bought some of the Lynn Fuston (sp?) CDS & thought on 1st listening that the PT in the box mix was  the one I preferred / the non box mix..

And upon knowing which was which - somehow suddenly the analogue mix seemed to be the one with 'vibe' and the PT box mix was plasticky..


THANK YOU.

And this is why in-the-box is losing to analog mixing...because it supposedly "vibier", even though it doesn't sound as good.  Definitely a case of the "King's New Clothes"

But if you go only by ear and not by fear of being shamed, most of the time you're really not going to like what all the extra fucked-up analog electronics are doing to your music.

George



There is GOOD analog and Bad analog, and GOOD digital and BAD digital.

GOOD analog such as the simple straight to two track recordings of the late 50's can sound amazing. BAD analog where it's gone through a big desk and multiple generations of tape looses a lot of fidelity, yet can still sound musical. GOOD Digital with a high quality recording path and no clipping can also sound amazing. But BAD digital, where the recording has been through poor converters, recorded or mixed too hot, over-limited, or whatever just sounds SH*T.

What I am saying is that although digital is a lot easier to work with, it is also a lot easier to destroy the music. If a lot of care is taken then the results can be magic. I think a skilled craftsman can get amazing results out of either medium.

There are so many people working with digital today that have no idea of the pitfalls of the medium. I recently had a project where the songs had been mixed with an L1 limiter on every track as then on the master stereo bus. This definitely had that BAD digital sound. Although with analog you needed a lot of skill and patience (and money), with digital you need just as much skill.

Best Regards

David C
Title: Re: George....what's the resolution of analog?
Post by: davidc on May 26, 2004, 04:04:06 am
St. Domingo's wrote on Tue, 25 May 2004 21:06

Quote:

DVD players, and other electronics that are not affected by vibration.


Ethan, please help this bear of little brain out.

Are you saying that DVD players are NOT affected by vibration?

One would assume anything that could cause eccentricity in disc rotation would affect the performance of a DVD player in the same way it can in a CD player.  Where am I going wrong?

Cheers,

Matt


Matt,

I think Ethan is saying he does not believe vibration effects ANY digital or solid state electonic devices.

Best Regards

David C
Title: Re: George....what's the resolution of analog?
Post by: josh on May 26, 2004, 10:22:43 am
Even though I posted earlier what my true belief is as to why some prefer analog over digital and insist that it sounds more real (psychoacoustic effects, auditory focus, etc.), I think there's also the matter of what's comfortable and familiar.

In general, I think most analog devices are colored enough to be considered an "effect" even if they are not intended to be used as an effect.  For example, a microphone preamp is obviously not intended to be an effect, just a gain device, but we all know that recording engineers carefully select microphone preamps precisely because of their characteristic sound or color, which is really using them as an effects device.

So if we agree that a Neve channel strip is colored enough that we select it as a mic pre based on color (using it as an effect), then of course when we run our digital recording outputs into these same channels for mixdown, clearly it's not "clean" or "transparent" we are going for with the "OTB" mix.  It's the very color we hear in the console that we want to add to the mix.  

It's certainly possible, even probable unless you believe the mythology that analog circuitry (such as a guitar amp or microphone) cannot be digitally modeled, that we could create the very same effect in the box if we quantified what that effect was in the first place.  So, for example, if we could accurately model the insertion behavior of a Neve 1073 and write an effects plugin that could be inserted on every channel of our ITB mix, and then do the same for a 1272 and insert it on the master channels of our ITB mix, then the audible difference between the ITB and OTB mix would be almost nil...  the difference based mostly on the quality of the modeling technology, and not whether it's ITB or OTB.

In the same way, if we could accurately model the behavior of analog tape, then we could insert a plugin to have that effect as well (attempts such as "magneto" show that there may be some market for that).

However, the real question is "why".  Is it that magnetic tape really is the *perfect* effect for musical recordings?  It can't be since it's so varying between different machines, types of tape, states of wear and disrepair, etc.  Is it that an SSL or Neve console channel really is the *perfect* insertion effect for mixing?  Again, logically, this can't be, because the anti-in-the-box mix crowd insists that nearly any technique of mixing "OTB" is an improvement over ITB.

So I think some of us are simply familiar with the sound of a recording on analog tape, can hear the difference with digital, and say analog is "better" simply because it's what we're used to.  In other words, we hear the digital recording and thing something is "wrong", because it's not what we were expecting to hear... the very definition of "wrong" is that it does not have the colored sound of analog tape.

In the same way with mixing on an outboard desk, many pros are very accustomed to the sound of a mix done through one of a few mixing desks and if it does not sound like *that* then it's "wrong" and the outboard mix is better.  However I think there's also the added factor with mixing of the comfort of the mixer...  they're used to using a particular format of mixer, uncomfortable mixing with a mouse, have gotten in the habit of using the EQ of a certain desk to make the kind of sound they want, etc.  It's all about habits and familiarity, really very little objective at all.

In the end, a generation of people will grow up not having gotten accustomed to hearing mixes first on analog tape, and through expensive large-format outboard mixers, and will master techniques of making great-sounding recordings and mixes using other tools.  The automatic compression and distortion of magnetic tape are somewhat of a crutch...  you can just simply lay down a guitar track and you don't need to treat it at all, it's ready to go with the tape compression.  With digital, you need to learn to use a compressor to get it right.  Using an outboard mixer imparts its own effect on the bandwidth, distortion, phase, etc. of a track, but eventually we'll learn how to tweak the digital in the box channel to get it to sound as good or better.  In the end, the digital tools are far more flexible and more capable of making great recordings, but we have not mastered their use by and large, so we still have a large contingent of engineers insisting that analog is "better" which actually means "I can make it sound better", also known as "I don't know how to make the digital stuff sound good".

Here's an analogy:  I can probably drive my Miata faster through a road race course than I could drive a Formula 1 car through the same course, simply because I don't know how to operate the gearbox on F1 car, I would spin out, it's unforgiving on going "over the limit", and I'm very used to driving my car since I've logged 20+ miles a day in it for the past 4 years.  Does that mean my car is a better road race car?  Absolutely not.  Saying "I can make my Miata go faster around the track" is a definition of my own personal limitations, not the limitations of the cars.  In the same way to say "I can make an analog recording sound better" is, imho, a definition of the AE's own personal limitations and not necessarily indicative of the strength or weakness of the medium.

I still think this whole analog vs. digital debate is much more about human perception, psychology, and other idiosynchrosies than is about technology.
Title: Re: George....what's the resolution of analog?
Post by: ted nightshade on May 26, 2004, 12:28:17 pm
I do think that human perception has a lot to do with it.We're limiting the optomized bandwidth to what humans could possibly perceive, which makes sense, if this is all being done for human listeners- it also makes sense to optomize other aspects of the kit to human ways of perception. This gets into psychoacoustics which is a very complex and often subjective business- none of us humans have an objective viewpoint, for that matter.

There's no question that whatever the nature of the components is, purely digital, purely analog, or a hybrid like converters must be, they have to be used carefully with awareness to get good results. Not using a component at all is one significant option. I recommend it! If it doesn't need to be in the chain, take it out of the chain. Every little thing makes such a difference!

As for myself, with any of the digital or analog gear I have used, it seems very much true that the less you do to that signal, the better, and the fewer things you try to sum, the better. Manipulating the signal a lot and summing many signals puts extreme demands on the gear, IMHO. It's always got to be a call about "is it worth it" sonically and musically. Mastering engineers seem very conscientious about this compared to recording engineers, overall..

I think the best results can be obtained when every step of the entire process, from selecting and tuning the instruments and the arrangement on, is taken with an awareness of the limitations and characteristics of every procedure and every component. It can be interesting and informative to make comparisons by swapping out any one component or procedure, but without a wholistic view of the entire system, things are ultimately compromised- as they so often are!
Title: Re: George....what's the resolution of analog?
Post by: Ethan Winer on May 26, 2004, 03:37:53 pm
Matt,

> Are you saying that DVD players are NOT affected by vibration? <

Yes, and neither are CD players. The stability of a CD or DVD drive mechanism is not important at all. These drives are not like a turntable, where instability of the drive motor directly impacts wow and flutter. Rather, the data is read from the disk into a memory buffer, and then a moment later it's sent out at a very uniform rate which is controlled by the clock circuitry.

This is why walkman style CD players often boast a large memory buffer, for when you're jogging and the player is frequently bumped and jostled. Since the buffer always holds the next few seconds of music, it can keep outputting until the mechanism has a chance to find the track again and resume reading.

--Ethan
Title: Re: George....what's the resolution of analog?
Post by: davidstewart on May 26, 2004, 04:48:22 pm
The large buffers do correct for intermittent data due to vibrations. However I have heard of a related issue that may have some validity. When an optical player cannot correctly read a block of data it will either correct with error correction, or may try to re-read the data. The momentary power supply draw from the extra servo movements can potentially cause inconsistencies in the clock (voltage drop presumably??), which could conceivably manifest themselves sonically at the D/A. Obviously this (or the severity of it) would depend on the player (power supply, etc.).

This is not something I've noticed personally, only heard about it, but it sounds plausible.

David Stewart
Title: Re: George....what's the resolution of analog?
Post by: davidc on May 26, 2004, 05:07:26 pm
davidstewart wrote on Wed, 26 May 2004 21:48

The large buffers do correct for intermittent data due to vibrations. However I have heard of a related issue that may have some validity. When an optical player cannot correctly read a block of data it will either correct with error correction, or may try to re-read the data. The momentary power supply draw from the extra servo movements can potentially cause inconsistencies in the clock (voltage drop presumably??), which could conceivably manifest themselves sonically at the D/A. Obviously this (or the severity of it) would depend on the player (power supply, etc.).

This is not something I've noticed personally, only heard about it, but it sounds plausible.

David Stewart


David,

I believe you are spot on with this. I have heard this phenomena. One interesting experiment you can try is weighting down the cd transport mechanism with lead tape and see if you can hear it effect the sound.

Best Regards

David C
Title: Re: George....what's the resolution of analog?
Post by: jfrigo on May 26, 2004, 05:26:37 pm
davidstewart wrote on Wed, 26 May 2004 13:48

The momentary power supply draw from the extra servo movements can potentially cause inconsistencies in the clock (voltage drop presumably??), which could conceivably manifest themselves sonically at the D/A.


Sounds like a properly designed power supply or a good external DAC would solve the problem.

Title: Re: George....what's the resolution of analog?
Post by: davidstewart on May 26, 2004, 05:55:38 pm
An external D/A (power supply separate from player) surely would solve this problem.

However, just adding an external power supply might not - it would still be common to the mechanical, analog, and digital parts of the device so it would be possible for the issue to remain. But I agree that a better quality PSU would likely make a positive difference.

David Stewart
Title: Re: George....what's the resolution of analog?
Post by: St. Domingo's on May 26, 2004, 06:35:45 pm
Apologies for unintentionally managing to derail the thread.

Quote:


The stability of a CD or DVD drive mechanism is not important at all. These drives are not like a turntable, where instability of the drive motor directly impacts wow and flutter. Rather, the data is read from the disk into a memory buffer, and then a moment later it's sent out at a very uniform rate which is controlled by the clock circuitry.

This is why walkman style CD players often boast a large memory buffer, for when you're jogging and the player is frequently bumped and jostled. Since the buffer always holds the next few seconds of music, it can keep outputting until the mechanism has a chance to find the track again and resume reading.

--Ethan


I'll have to strongly disagree with you on the suggestion about a CD mechanism's stability.

Firstly, most domestic hifi CD players play at 1* speed.  I'll come back to this in a second...

The FIFO buffering you talk of eliminates playback jitter in the data stream coming off the disc, I'll accept that.  However, jitter inherent on a badly pressed / burnt CD (and also caused by physical vibration of a playback mechanism) has two effects:

1- timing errors in the data coming off the disc (which you will have eliminated in the buffering).

2- The ability for the servo systems to ensure the correct data is retrieved.

If the correct data cannot be read, the error correction will kick in.  The more errors that need correcting, the more audible it becomes.

Mini-disc was the first technology I'm aware of to use very large FIFO buffers.  It was however designed to read discs in very fast bursts, giving it time to go back and reread sections.  This allowed the "non-skip" operation.  I can only assume that modern "Walkman-type" Cd players make use of multi speed data mechanisms to operate in a similar manner (I'm not intimately familiar with these types of players).  I know of no non"Walkman-type" audio CD players that read data in bursts like this.

It is my first hand experience that the stability of a 1* audio CD mechanism has a fundamental effect on the the number of errors read from the drive and hence can have an audible effect on the CD players output.

As I said, if you can explain where I'm going wrong I'm all ears, but please do it in a new thread as I'm sure people's patience with me is getting thin.
Title: Re: George....what's the resolution of analog?
Post by: Paul Frindle on May 26, 2004, 07:17:00 pm
I'll have to strongly disagree with you on the suggestion about a CD mechanism's stability. Firstly, most domestic hifi CD players play at 1* speed.  I'll come back to this in a second...The FIFO buffering you talk of eliminates playback jitter in the data stream coming off the disc, I'll accept that.  However, jitter inherent on a badly pressed / burnt CD (and also caused by physical vibration of a playback mechanism) has two effects:1- timing errors in the data coming off the disc (which you will have eliminated in the buffering).2- The ability for the servo systems to ensure the correct data is retrieved.If the correct data cannot be read, the error correction will kick in.  The more errors that need correcting, the more audible it becomes.



Quite apart from actual data errors and correction, another class of problem can indeed arise out of the efforts and machinations of the servos as they track. In this case the modulation of the power supply and internally generated PCB earth currents cause the clock transmission and converter stages to degrade - even though there are no data errors.

Obviously the gravity of this effect is closely related to the quality of the design of the circuits and should not affect a player with an external DAC that additionally has good clock recovery stages (i.e. PLL). However, many even high costing players do not have this facility.
Title: Re: George....what's the resolution of analog?
Post by: George Massenburg on May 26, 2004, 07:25:21 pm
A note to members of the forum.  

Paul Frindle is one of the best in an already highly stratified group of analog & digital audio processing and electronics designers.  His being one of a very few mixed-signal designers, however, puts him in a class of only a handful of engineers in the world.

Please listen to him carefully.

George

p.s. On the downside, I suppose I should mention that Paul's deeply tobacco-addicted and is regrettably no longer willing to fly around to shows and other places where you might chat about audio...
Title: Re: George....what's the resolution of analog?
Post by: djui5 on May 26, 2004, 08:15:48 pm
Welcome Paul.

I look forward to your knowledge.
Title: Re: George....what's the resolution of analog?
Post by: davidc on May 27, 2004, 05:03:35 am
Paul Frindle wrote on Thu, 27 May 2004 00:17

I'll have to strongly disagree with you on the suggestion about a CD mechanism's stability. Firstly, most domestic hifi CD players play at 1* speed.  I'll come back to this in a second...The FIFO buffering you talk of eliminates playback jitter in the data stream coming off the disc, I'll accept that.  However, jitter inherent on a badly pressed / burnt CD (and also caused by physical vibration of a playback mechanism) has two effects:1- timing errors in the data coming off the disc (which you will have eliminated in the buffering).2- The ability for the servo systems to ensure the correct data is retrieved.If the correct data cannot be read, the error correction will kick in.  The more errors that need correcting, the more audible it becomes.



Quite apart from actual data errors and correction, another class of problem can indeed arise out of the efforts and machinations of the servos as they track. In this case the modulation of the power supply and internally generated PCB earth currents cause the clock transmission and converter stages to degrade - even though there are no data errors.

Obviously the gravity of this effect is closely related to the quality of the design of the circuits and should not affect a player with an external DAC that additionally has good clock recovery stages (i.e. PLL). However, many even high costing players do not have this facility.



Hi Paul,

In my experience, the cd servo mechanism is extemely sensitive. You can effect it through vibration, light, or by adding removing weight. Also the effects are audible in an external DAC, even with a PLL (yes it reduces the effect).

Best Regards

David C
Title: Re: George....what's the resolution of analog?
Post by: George Massenburg on May 27, 2004, 09:04:51 am
St. Domingo's wrote on Wed, 26 May 2004 17:35


[...]
I'll have to strongly disagree with you on the suggestion about a CD mechanism's stability.
[...]
The FIFO buffering you talk of eliminates playback jitter in the data stream coming off the disc, I'll accept that.  


You shouldn't.

If we're talking about consumer-class CD players, the box's re-clocking circuit (or code) in every case I can think of (and I'm anxious to be corrected) depends on a time-base set by a crystal - in most cases a modest one.  When we were doing jitter tests in the late 80's, the best jitter detector was built by Ed Meitner with a clock stabilizer designed by Bruce Jackson.  As nearly as we could tell - which is to say, we had no primary or secondary certified reference - we could measure peak-to-peak broadband jitter into the single-digit nanoseconds (more of an accomplishment at the time than it would seem today).  What we saw were some crystals that were significantly high in jitter. But, worse, almost all of the crystals we tested were sensitive to one degree or another to mechanical noise.  And where is the player most of the time?  Pretty close to the speakers.  And naturally the jitter increase is more dramatic the louder you listen.

I'd love to hear about a K-1 circuit and/or a precision crystal (or stabilized atomic) reference in a consumer player, but I sort of doubt it.

Quote:


However, jitter inherent on a badly pressed / burnt CD (and also caused by physical vibration of a playback mechanism) has two effects:

1- timing errors in the data coming off the disc (which you will have eliminated in the buffering).


Not.
Quote:


2- The ability for the servo systems to ensure the correct data is retrieved.
[...]



Again, only up to the point where an known-accurate time-base can be established.

George
Title: Re: George....what's the resolution of analog?
Post by: Ethan Winer on May 27, 2004, 11:04:27 am
David,

> The momentary power supply draw from the extra servo movements can potentially cause inconsistencies in the clock <

I think it's important to keep the magnitude of these things in perspective. Okay, maybe it's possible to measure that jitter increases slightly when you put the D/A convertor on top of the loudspeaker, or you whack it a few times with a drum stick. So it goes from -120 dB all the way up to -110 dB. Who cares? Surely not me. Just because you can measure an error doesn't mean it's important or even audible.

--Ethan
Title: Re: George....what's the resolution of analog?
Post by: Former Oceanway drone on May 27, 2004, 12:09:03 pm
Ethan Winer wrote:

"Just because you can measure an error doesn't mean it's important or even audible."

I would say two things:

First, some of the people in this discussion are saying that just because it can not be measured does not mean that it is not audible. Some of the more "just give me the facts" people have even declared that if it is not measurable, it does not exist. But now to say that even if it is measurable it may not be important seems to me to be changing standards.

Second, with respect to the buffer discussion, I have heard a portable CD player that was having such amazing difficulty tracking while resting on the floor that the distortion it was producing made all music played on it quite, well, unlistenable. The machine in question had undoubtedly been abused, but I would assume (at my peril perhaps) that the less vibration that a CD player experiences, the less the servos have to work to track correctly and therefore the less likely that error correction will be called into play. I have heard error correction, and it is not pretty.

If all that I have written here is irrelevant, I apologize sincerely.

Cheers,

Alan Tomlinson
Title: Re: George....what's the resolution of analog?
Post by: josh on May 27, 2004, 01:53:00 pm
Former Oceanway drone wrote on Thu, 27 May 2004 17:09

Ethan Winer wrote:

"Just because you can measure an error doesn't mean it's important or even audible."

I would say two things:

First, some of the people in this discussion are saying that just because it can not be measured does not mean that it is not audible. Some of the more "just give me the facts" people have even declared that if it is not measurable, it does not exist. But now to say that even if it is measurable it may not be important seems to me to be changing standards.



Both are likely true.

There are likely measurable electrical phenomena in audio electronics that are not at all audible.  2nd order distortion above a 30 kHz fundamental tone would be an example.

There are also likely audible phenomena that we do not routinely measure, or are unable, incapable, or unaware of the need to measure.  

There is also the placebo effect, which can certainly be verified, and may likely be responsible for much of the belief in the phenomena of audible, yet immeasurable or unmeasured effects.

When I first started working with DSL modem analog front ends back in '96, we found that we could detect distortion due to capacitors in use in DSL modems that was not measurable by any test equipment or method that was available at the time.  We determined that until the test technology caught up, we had to characterize capacitor performance by inserting capacitors into a functioning modem system and then measuring the system's performance and extrapolating the distortion by its effect on performance.  This was a recognizable effect of an unmeasurable (at the time) phenomenon.  Certainly the same must be true of audio electronics, and is always true of any scientific endeavor.  Capacitors, distortion, and analog performance of a dielectric component are and were in '96 considered to be well-understood technology.

Later on I worked on a telecommunication front end that employed a fuse which caused a fire.  This fuse caused a fire due to a previously unmeasured effect of the design of a spiral-wound fuse.  Once the effect was recognized, immediately the engineers involved in the fuse design and application determined an easy way of measuring it.  However, until the effect itself was observed and quantified, there was no reason to measure the parameters that provided the risk.  Certainly there are effects in audio that we have yet to fully quantify, and therefore we are not even aware that we should measure them, which is not to say they can't be measured.

On the other hand, I am not anything like an audio engineer but I can identify just off the top of my head many measurable parameters of audio circuit design that, provided they are under a particular threshold, are not important at all for audio.  To Ethan's point, he didn't say that it was something that was not necessary to measure or control at all, but in fact that it was such a low level that it is not important to audio.  In other words, we measured it, and determined that it is acceptable.

For example, a change of SNR from 150 dB to 200 dB may be completely measurable, and certainly this difference is significant mathematically, but since both are beyond the threshold of human hearing, neither level is important to audio.  When the number gets closer to 140dB it begins to become important to measure.
Title: Re: George....what's the resolution of analog?
Post by: St. Domingo's on May 27, 2004, 02:14:01 pm
George and Paul (where are the other two? Razz  ), thanks very much for putting me straight.  This really is a wonderful environment in which to learn.

Ethan
Quote:


"Just because you can measure an error doesn't mean it's important or even audible."



You can measure "totally correctable" errors on CDs and also "uncorrectable" errors.  The CD format is based around error identification and correction.  Of course no disc is measurable by itself; you're always also measuring the mechanism you are playing the disc back on, and everything that comes with that (servos PSU etc...).

Uncorrectable errors are by definition inportant and audible given the mechanisms available to deal with them (interpolate / mute).

I've never tried to set-up a test to impart controlled vibration of a CD player and listen.  I have observed eccentric disc rotation (bent spindle motors) and its effect on eye-pattern jitter, tracking servos, errors and sonics, albeit in a workshop environment.  It is IMVHO very noticeable, and very important.

Matt.
Title: Re: George....what's the resolution of analog?
Post by: davidstewart on May 27, 2004, 06:35:28 pm
Ethan,

You said

"I think it's important to keep the magnitude of these things in perspective. Okay, maybe it's possible to measure that jitter increases slightly when you put the D/A convertor on top of the loudspeaker, or you whack it a few times with a drum stick. So it goes from -120 dB all the way up to -110 dB. Who cares? Surely not me."

I say
I don't recall mentioning anything about how much of an effect this has. Have you made those figures up, or do you know this for a fact?  I did intimate that people have been able to hear the effect, and at least one other person here confirms it.

You said
" Just because you can measure an error doesn't mean it's important or even audible."

I say = Agreed. I don't care if it isn't audible.

Title: Re: George....what's the resolution of analog?
Post by: Ethan Winer on May 28, 2004, 01:55:23 pm
Alan,

> some of the people in this discussion are saying that just because it can not be measured does not mean that it is not audible. <

I dispute that strongly. What could possibly be audible that can't be measured? We can measure frequency response beyond the limits of audibility. We can measure distortion to well under 100 dB below the music. We can measure jitter (encompassing wow and flutter) to far lower than that. We can measure background noise (encompassing tape modulation noise) to at least that low too. So what else is there? IMO all the claims of "audible but not measurable" I've ever seen are based on magical thinking. It's the magical thinking that I object to.

> to say that even if it is measurable it may not be important seems to me to be changing standards. <

Again, we can measure distortion and jitter so far below the music it can't possibly be audible. Why is that a leap?

> The machine in question had undoubtedly been abused <

Right, broken devices don't count. More important, surely whatever you heard could be easily measured.

--Ethan
Title: Re: George....what's the resolution of analog?
Post by: Ethan Winer on May 28, 2004, 02:01:02 pm
David,

> Have you made those figures up, or do you know this for a fact? <

Yes, I made those numbers up just to use as an example.

> people have been able to hear the effect, and at least one other person here confirms it. <

This is why a double-blind test is so important to distinguish between placebo effect and a real change in the sound.

--Ethan
Title: Re: George....what's the resolution of analog?
Post by: Level on May 28, 2004, 02:31:57 pm
Hi Ethan!


You cannot measure the difference between my hearing/perception and your hearing/perception.

Cannot be done...yet their is a difference.

Too many parameters to measure. Subjective differences.
Title: Re: George....what's the resolution of analog?
Post by: interstellar sasquatch on May 28, 2004, 03:30:20 pm
Well when I hear the term resolution mentioned it is usually referring to bits. So that would essentially correlate to dynamic range or signal to noise ratio on the analog side. In terms of frequency response you have the nyquist theorom sampling rate 2x frequency response etc.  (think that is what it is called). I think on the analog side that might correlate to tape speed? Loosely.

But I think the answer might be harmonic content. The analog side of things has richer/denser harmonics.  Of course that richer denser harmonic content and the tendency to distort more gradually also helps mask those farts and guffaws made by your clients in the middle of tracking.

Mike
Title: Re: George....what's the resolution of analog?
Post by: djui5 on May 29, 2004, 04:32:32 am
interstellar sasquatch wrote on Fri, 28 May 2004 13:30

Well when I hear the term resolution mentioned it is usually referring to bits.
Mike


I have a question that's a tad OT but has been brought up so many times on this thread alone I feel it needs to be addressed


Will there ever be a set in stone definition for resolution in it's reference to audio whether that be digital or analog?

I've seen dictionary definitions posted and the disagreements still progress....

Personally I feel it would be of great communical importance to clear this up as the lack of "set in stone" definition seems to be causing quite a bit of confusion.

Then again maybe I had too much coffee today...
Title: Re: George....what's the resolution of analog?
Post by: jfrigo on May 29, 2004, 04:12:55 pm
djui5 wrote on Sat, 29 May 2004 01:32

Will there ever be a set in stone definition for resolution in it's reference to audio whether that be digital or analog?



It depends if you are using the term subjectively or objectively in reference to digital audio. As a technical term as applied to digital audio it refers to the bit depth. As a subjective term that can be applied to anything from monitors to mixes to, albeit confusingly, digital audio, it of course refers to the detail and all that.

In a technical discussion of digital audio, if you are using it in the subjective sense, you should add a disclaimer to avoid confusion. If you are talking about speakers, however, nobody is likely to confuse it with an objective measurement of dynamic range.

Title: Re: George....what's the resolution of analog?
Post by: Curve Dominant on May 30, 2004, 01:40:49 am
Quote:

djui5 wrote on Sat, 29 May 2004 01:32:

Will there ever be a set in stone definition for resolution in it's reference to audio whether that be digital or analog?


That's a question which intrinsically answers itself, no?

In other words, if you have to ask that at this late stage of the game, it tells you that the term is too vague for engineering purposes, because no one has definitively answered it so far.

So one can interpolate from that experience that "resolution" is an abstract term. No? So where is there room in the engineering sciences for abstraction?

Bit depth is definable.

Sampling rate is definable.

Dynamic range is definable.

SNR is definable.

One can sum these factors, and concievably choose to blanket that sum into a "resolution" factor, but that is still a very subjective exercise, because:
1) Who's authority is it to scale those factors into a "resolution" factor??, and
2) Isn't it insulting to the average engineer's intelligence that they cannot sort out the individual factors, and make up their own mind what is optimal "resolution" without third-party critics imposing vague and un-verifiable "resolution" standards?

This term "resolution" is a cop-out for people who do not understand the basics of recording, yet seek to justify some abstract notion of what they cannot achieve.
Title: Re: George....what's the resolution of analog?
Post by: Dougtune on May 30, 2004, 12:09:20 pm

Ethan said:
(QUOTE)
Some of the people in this discussion are saying that just because it can not be measured does not mean that it is not audible.
I dispute that strongly. What could possibly be audible that can't be measured? We can measure frequency response beyond the limits of audibility. We can measure distortion to well under 100 dB below the music. We can measure jitter (encompassing wow and flutter) to far lower than that. We can measure background noise (encompassing tape modulation noise) to at least that low too. So what else is there? IMO all the claims of "audible but not measurable" I've ever seen are based on magical thinking. It's the magical thinking that I object to.
(UNQUOTE)

Ethan, the measurements that can made today tell only a small part of the story.  You mention frequency response (BRIGHT vs DARK), distortion (CLEAN vs DIRTY), jitter (DIGITAL ARTIFACTS), and noise (NOISEY vs QUIET).  

But how do you "measure" DEEP vs SHALLOW, ROUND vs FLAT, SILKY vs GRITTY, IRON vs WIMPY, RHYTHMIC vs CLINICAL, HARSH vs PRETTY, or PRESENT vs DISTANT?  Only with ears.
Title: Re: George....what's the resolution of analog?
Post by: Ethan Winer on May 31, 2004, 11:02:13 am
Doug,

> how do you "measure" DEEP vs SHALLOW, ROUND vs FLAT, SILKY vs GRITTY, IRON vs WIMPY, RHYTHMIC vs CLINICAL, HARSH vs PRETTY, or PRESENT vs DISTANT? <

Some of those intentionally vague terms can indeed be translated to conventional measurements, and some of them (present vs distant) relate more to room acoustics than audio fidelity. For example, to my way of thinking "harsh" is a frequency response issue. And "iron vs wimpy" and "rhythmic vs clinical" seem frankly silly. Sorry.

--Ethan
Title: Re: George....what's the resolution of analog?
Post by: Bill Mueller on May 31, 2004, 11:11:12 am
Doug,

You forgot one. Pink verses Blue.

Bill
Title: Re: George....what's the resolution of analog?
Post by: ted nightshade on May 31, 2004, 01:44:47 pm
I'm intrigued by the idea that harmonic content is one way of looking at resolution... then there's detail.

Here's a real-life scenario- I played a tape into a Cranesong HEDD 192, with and without process. The tape has details and harmonic content that don't make it into the HEDD. The HEDD with process gains from the harmonic generation, but detail is lost- my unexamined (at the time) take was that with the process (set at 0,0,0, or any other way), the signal lost resolution. It became a bit vaguer and less specifically detailed and intricate, compared to how it was in bypass.

Anyhow that's what I'm thinking about here- resolution seems to me to be about detail and dimension, and harmonics play a part in it, but not to the exclusion of other aspects of detail and dimension. There's nothing nebulous and vague about higher resolution, in listening terms- quite the opposite! Higher resolution is less nebulous, and less vague.

Anyhow.
Title: Re: George....what's the resolution of analog?
Post by: Giovanni Speranza on May 31, 2004, 05:03:50 pm
Pro Analog machines have those specs:
25-25000 Hz,
with DBX 100 dB dynamics
Title: Re: George....what's the resolution of analog?
Post by: ted nightshade on May 31, 2004, 06:52:25 pm
Giovanni Speranza wrote on Mon, 31 May 2004 14:03

Pro Analog machines have those specs:
25-25000 Hz,
with DBX 100 dB dynamics



I don't know if mine is pro or not, but it does 20-30,000 Hz on the tape they had in 1968- I wonder what it does on modern tape? The S/N is more like 65 dB, but you can hear a ways under the noise floor, and actually, 65 dB seems like a lot- ppp to fff anyway. Who here is even using that much with whatever they got?
Title: Re: George....what's the resolution of analog?
Post by: Giovanni Speranza on May 31, 2004, 08:04:16 pm
Put a DBX and you will almost double the SN ratio, or use Dolby SR.
We have to remember that most of the best recordings were made on those noisy tape machines, but never without Dolby or DBX nr.
Title: Re: George....what's the resolution of analog?
Post by: dwoz on June 01, 2004, 01:02:30 am
Eric Vincent wrote on Sun, 30 May 2004 10:40

Quote:

djui5 wrote on Sat, 29 May 2004 01:32:

Will there ever be a set in stone definition for resolution in it's reference to audio whether that be digital or analog?


That's a question which intrinsically answers itself, no?

In other words, if you have to ask that at this late stage of the game, it tells you that the term is too vague for engineering purposes, because no one has definitively answered it so far.

So one can interpolate from that experience that "resolution" is an abstract term. No? So where is there room in the engineering sciences for abstraction?




What a breathtaking, spectacular leap.  I'm reminded of Nuryev in "Swan Lake", in his duet with Odette.

The word is quite satisfactorily defined, and used without consternation nor confusion the world over, except perhaps in the culinary arts.  Like many other terms, it is indeed context-sensitive.  Culinary artists hate context sensitive measures, unless they're cajun.

Take the word, "big".  oh, my...big WHAT?  we talkin' feet, inches, volts, pascals, watts, couloumbs, foot-pounds, Length-at-the-waterline...lunch rush...damn me, WHAT IS BIG?

Is it RELATIVE?  a 2 volt input signal is "big" if you ask a mic pre...but what if you ask a power transmission line?  

In floating point math, resolution is also called precision, or # of significant digits.  plenty more examples, from pharmacology to astronomy...

dwoz


Title: Re: George....what's the resolution of analog?
Post by: Zoesch on June 01, 2004, 01:28:39 am
Incredibly funny considering that Engineering is a science of abstraction and approximations!
Title: Re: George....what's the resolution of analog?
Post by: ted nightshade on June 01, 2004, 10:51:46 am
Giovanni Speranza wrote on Mon, 31 May 2004 17:04

Put a DBX and you will almost double the SN ratio, or use Dolby SR.
We have to remember that most of the best recordings were made on those noisy tape machines, but never without Dolby or DBX nr.


A lot of the best recordings I've heard were circa 1959... no dolby there! I'm a puriste, I'd rather skip it. But it would be interesting to try... I've used both a little bit, and was far from delighted, but I probably did not get to try to the best implementations of either.
Title: Re: George....what's the resolution of analog?
Post by: Han S. on June 01, 2004, 01:09:06 pm
DBX sounds muddy in the lows and with the +9 tape you don't need any NR when recording pop music Giovanni.

Dolby A, S or SR will sound better than DBX and my two inch machine records a 35 khz sine with ease.
Title: Re: George....what's the resolution of analog?
Post by: Giovanni Speranza on June 01, 2004, 02:24:47 pm
Han S. wrote on Tue, 01 June 2004 18:09

DBX sounds muddy in the lows and with the +9 tape you don't need any NR when recording pop music Giovanni.

Dolby A, S or SR will sound better than DBX and my two inch machine records a 35 khz sine with ease.


That's great Han. To get those specs we need  at least 70 kHz digital sampling.
Title: Re: George....what's the resolution of analog?
Post by: ranalog on June 01, 2004, 04:41:43 pm
it sounds better because its "MAGIC!!"  heres one, Digital is a flourescent light bulb, flashing so fast you cant tell, but it kind of annoys...Yes?  anolog is like a smooth burning incandesent light bulb,  just a thought, If all you people only knew..... Ranalog
Title: Re: George....what's the resolution of analog?
Post by: Nika Aldrich on June 01, 2004, 05:10:51 pm
ranalog wrote on Tue, 01 June 2004 21:41

it sounds better because its "MAGIC!!"  heres one, Digital is a flourescent light bulb, flashing so fast you cant tell, but it kind of annoys...Yes?  anolog is like a smooth burning incandesent light bulb,  just a thought, If all you people only knew..... Ranalog


Yeah, that kinda sucked.

Both analog and digital get reproduced as analog waveforms out speakers.  At some point the digital waveform has to become an analog waveform again in order to do so.

Nika.
Title: Re: George....what's the resolution of analog?
Post by: oudplayer on June 01, 2004, 05:15:42 pm
Noise, for us, is 80dB or more under peak volume when we transfer tapes from an Otari MTR90 24 track. Without any dolby. Considering the fidelity of the final delivery medium, tape noise hasn't been an issue for us. Guitar amp hum, that's a whole different story...
Title: Re: George....what's the resolution of analog?
Post by: Paul Frindle on June 01, 2004, 07:11:33 pm
Eric Vincent wrote on Sun, 30 May 2004 06:40

Quote:

djui5 wrote on Sat, 29 May 2004 01:32:

Will there ever be a set in stone definition for resolution in it's reference to audio whether that be digital or analog?


That's a question which intrinsically answers itself, no?

In other words, if you have to ask that at this late stage of the game, it tells you that the term is too vague for engineering purposes, because no one has definitively answered it so far.

So one can interpolate from that experience that "resolution" is an abstract term. No? So where is there room in the engineering sciences for abstraction?

Bit depth is definable.

Sampling rate is definable.

Dynamic range is definable.

SNR is definable.

One can sum these factors, and concievably choose to blanket that sum into a "resolution" factor, but that is still a very subjective exercise, because:
1) Who's authority is it to scale those factors into a "resolution" factor??, and
2) Isn't it insulting to the average engineer's intelligence that they cannot sort out the individual factors, and make up their own mind what is optimal "resolution" without third-party critics imposing vague and un-verifiable "resolution" standards?

This term "resolution" is a cop-out for people who do not understand the basics of recording, yet seek to justify some abstract notion of what they cannot achieve.


Darned right on Smile The term resolution cannot be applied in any definable sense to audio either analogue or digital. It means absolutely nothing what so ever in any defensible language definition. It has been hijacked and coined by marketeers (for dubious reasons) and people are searching manically to assign it a real life meaning - completely in vain. It's just so sad Sad
Title: Re: George....what's the resolution of analog?
Post by: Zoesch on June 01, 2004, 11:41:55 pm
Paul Frindle wrote on Wed, 02 June 2004 09:11

Darned right on Smile The term resolution cannot be applied in any definable sense to audio either analogue or digital. It means absolutely nothing what so ever in any defensible language definition. It has been hijacked and coined by marketeers (for dubious reasons) and people are searching manically to assign it a real life meaning - completely in vain. It's just so sad Sad



You know, I kinda find it insulting when non EE's try to rephrase terms to fit their understanding of the world, it's called defending the indefensible.

Has the term been vilipended by countless circular arguments around its meaning? Certainly... if you don't like the term resolution because it (correctly) paints a picture of a discrete time system in your mind then the problem is not the term, is your refusal of applying the terms properly.

Is resolution bit depth, sample rate or dynamic range? Neither and all... how fine you want to resolve your signal to and to which base unit again?
Title: Re: George....what's the resolution of analog?
Post by: Zoesch on June 02, 2004, 09:33:03 am
Oh and to drive the point further...

Q: What's the resolution of a digitized signal?
A: One sample
Title: Re: George....what's the resolution of analog?
Post by: Nika Aldrich on June 02, 2004, 09:57:59 am
Zoesch wrote on Wed, 02 June 2004 04:41

...if you don't like the term resolution because it (correctly) paints a picture of a discrete time system in your mind then the problem is not the term, is your refusal of applying the terms properly.


I don't think that anyone is saying that the term cannot somehow be applied to this situation, but doing so is to use poor communication.  A digital system is merely a representation of an analog waveform.  It is not, unto itself, a waveform.  It merely represents the waveform.  To dig in to the "resolution" of various characteristics of the samples themselves is to, in effect, deny the end result.  It is far more appropriate to discuss the effects on the samples in relation to the end result (the analog waveform) and not as though the samples themselves were somehow the ends unto themselves.

When we discuss changing bit depths, for example, it is far more appropriate to discuss this change in terms of how it affects the signal that the digital data represents rather than simply discussing the samples themselves and how they might change independant of the net result.  Since the term "resolution" is not particularly applicable to analog waveforms it becomes a poor choice to use the term when discussing digital representations of those waveforms and therefore becomes an indication that the person using the term often has a separation in their minds between the digital representation and the analog waveform itself.  When people use that term it often leads me to think that they  have a disconnect with regards to digital audio in this capacity.  Harping on the use of the term can have the effect of getting people to recognize where the lapse in their understanding is.

Nika
Title: Re: George....what's the resolution of analog?
Post by: Zoesch on June 02, 2004, 10:06:13 am
Now this I can wholeheartedly agree with.
Title: Re: George....what's the resolution of analog?
Post by: ted nightshade on June 02, 2004, 11:30:04 am
Agreed we oughta judge digital recording by what comes out the other end in analog, since we can't very well hear it as digital.

Frustrating that what comes out will be different depending on the D/A that does it, but really no different than analog tape recording in that way- what machine you play it back on makes a big difference.
Title: Re: George....what's the resolution of analog?
Post by: Paul Frindle on June 02, 2004, 11:34:24 am
Zoesch wrote on Wed, 02 June 2004 14:33

Oh and to drive the point further...

Q: What's the resolution of a digitized signal?
A: One sample


Err no! One sample is but a snapshot of ONE value within a CODED transfer system, wherein the history and future samples are all equally related. It is this simple perception that is at the root of the misunderstanding that allows the notion of 'resolution of audio signals' to falsely propagate amongst confused users.
Title: Re: George....what's the resolution of analog?
Post by: Johnny B on June 02, 2004, 12:56:53 pm
Hmmm. Some of you guys are great writers --- smart and funny too!

It seems to me that people are looking for a way and some useful nomenclature (words) to compare and discuss analog vs. digital.

Strange, that after all this time it seems to be both difficult to precisely define the terms and to arrive at a universal understanding and agreement. So I like simple, "Oscar Meyer's Razor," 'splanations because I'm from the "    only-two-brain-cells-left-and-they-aren't-talking-to-each-ot her school," so YMMV.

Due to GM's post re: the Euphonix/Sony joint deal, I gave a friend a call because he works for Euphonix and asked "What's up mmmaaan?" His reply was brief and concise, simple and direct, he said, "Think DSD."

I did not ask him what the resolution was because what I'm really interested in is whether it sounds good or not. Simple mind, ya know?





   


Title: Re: George....what's the resolution of analog?
Post by: ted nightshade on June 02, 2004, 01:36:00 pm
My subjective understanding of resolution is that it's something you can change with a move of the mic! Is that quantifiable? I sure can hear it.
Title: Re: George....what's the resolution of analog?
Post by: Curve Dominant on June 03, 2004, 02:24:07 am
Quote:

Paul Frindle wrote on Wed, 02 June 2004 09:11

Darned right on  The term resolution cannot be applied in any definable sense to audio either analogue or digital. It means absolutely nothing what so ever in any defensible language definition. It has been hijacked and coined by marketeers (for dubious reasons) and people are searching manically to assign it a real life meaning - completely in vain. It's just so sad

Zoesch responds:
You know, I kinda find it insulting when non EE's try to rephrase terms to fit their understanding of the world, it's called defending the indefensible.



Zoesch,

I believe Mr. Frindle IS an EE, with some distinction might I add.

I am not an EE by trade per se, but I have learned much of what I know about digital audio from Mr. Frindle.

Granted, that does not make me an expert on the subject. However, this aversion to the term "resolution" as it applies (or more succinctly, how it DOES NOT apply) to digital audio, is one of the major lessons Mr. Frindle lent to my understanding of this subject.

Put more bluntly: Mr. Frindle was not simply agreeing with what I said, but rather, he taught me to think that way.

I am admittedly a "user" of my gear, not a designer or builder of it. But in seeking to use my gear to its optimal potential, I seek to understand it as much as possible, and I believe this should be encouraged.

There is nothing in our craft which cannot be explained to and understood by the layman, in terms that render the information usable, even if that knowledge is understood only on an intuitive level.

Hence the desire to purge confusing terms such as "resolution" from our dialogue.

Here's hoping we can bury the axe in that regard.
Title: Re: George....what's the resolution of analog?
Post by: ted nightshade on June 03, 2004, 12:52:43 pm
We'll be fumbling for some kind of word to try to describe some of these slippery hard-to-quantify aspects of audio that can seem so critical, what with all the dancing about architecture we do... agreed, probably best if such terms don't masquerade as technical terms.

So, I finally heard some converters that sound as good, overall, as my beloved analog tape machine. Not sure that the SLAM! converters are the equal of the analog machine in every way, but in some important ways they are superior, and in many they definitely rival. I don't mind the noise, but the analog tape is sounding pretty hardening-of-the-arteries... Maybe I ought to try another kind of tape? I'm using Quantegy 456. 
Title: Re: George....what's the resolution of analog?
Post by: George Massenburg on June 03, 2004, 01:42:58 pm
Here's what 'resolution' means to me, and why I've used the word (in fact, have used it for some time, and have been obliged to observe increasingly its misuse)

Resolution is the ability to discern a relatively subtle signal; often this signal of interest is found in the presence of a larger signal, but also perhaps it's only being compared to a larger signal.

In analog systems, we more or less take resolution for granted.  There was such a time in the early 70's when Doug Sax began releasing "Direct To Disk" recordings which redefined what a recording chain could do.  

In our own work, we found that there were certain components and techniques that we had taken for granted that were, under the scrutiny of carefully controlled listening, likely to corrupt an audio chain.  Capacitors are certainly able to adversely affect not only basic spectral response, but also to adversely affect the perception of detail (we had thought that this perceived effect on "resolution" may have been the termination technique, perhaps the possiblity of a slightly non-linear termination).  That was only the beginning.

In digital, it's clear that when we started doing more accurate conversion, and more capable dithering, that we absolutely heard a difference in resolution.  And you know what I mean - forgive me...I simply don't know what else to call it.

Sorry to inform everyone that we didn't stop to objectify/calibrate "resolution" before it was co-opted by the hypermarketters.

Uh, can someone else pick up the work once in a while?

George
Title: Re: George....what's the resolution of analog?
Post by: Nika Aldrich on June 03, 2004, 02:36:45 pm
George,

Two points.  Your use of the word "resolution" is certainly consistent with a term we bandy about in the industry quite a bit referring to a euphonic characteristic of music, akin to "detail."  I put forth that in that purely subjective, euphonic framework it is probably a perfectly resonable term to use.  I do so myself when describing the difference between microphones or reverb tails or whatever to clients.  

The problem is clearly that people make the correlation between statistical resolution of digital systems with the subjective resolution of audio.  Thus, I think it is reasonable to simply not use the term when describing the bit depth or sample frequency related issues of digital systems.

Having said this, however, there is indeed a use of the term even in the digital realm that seems to be accepted in the engineering community as a whole, and that has to do with the level of accuracy in a floating point system.  We know that a 32 bit floating point system theoretically provides around 1500dB of dynamic range capability, but only with the accuracy at any given moment of 150dB.  This measurement of accuracy is called "resolution," apparently.  So a 32 bit float system with a 24 bit mantissa is said to have 1500dB of dynamic range and 150dB of resolution and a 32 bit float system with a 20 bit mantissa is said to have 6000dB of dynamic range with only 126dB of resolution.

I have avoided bringing this up until now simply to avoid further confusion regarding the term.  I have no objection at all to people saying that something has "more resolution," but unless it has more euphonic "detail" or greater instantaneous dynamic range in a floating point system I posit that their use is incorrect and draw the conclusion that they have a discorrelation regarding digital audio that I referred to earlier.

Nika.
Title: Re: George....what's the resolution of analog?
Post by: Johnny B on June 03, 2004, 03:19:28 pm
Sounds like Ted likes his SLAM, and that it compares favorably to his analogue systems. Perhaps those Manley folks know a little something about doing a good implementation of a box. LOL

Not sure how I would try to use the term "resolution" in regard to analogue, just that good systems "have it," while bad systems don't. Maybe it's like Nika said and can be used in relation to "detail" or like GM said and be used in terms of 2 signals and bad caps. I dunno.

When I think of "resolution" with regard to digital, it has something to do with the "precision" of the math, I think I read somewhere that old FP systems could introduce rounding errors but that the interger systems did not. As usual, both systems have advantages and disadvantages and involve making trade-offs at times. But here, are we not striving for somne agreed upon standard of excellence. That's what we are all looking for, isn't it?  Excellence?

Glad to hear that Ted seems to like his Slam, I think some "ear people" and "audiophile" folks helped out with that box.






Title: Re: George....what's the resolution of analog?
Post by: josh on June 03, 2004, 04:15:31 pm
Perhaps the problem is that the term "resolution" has a relatively commonly-held range of definition in the vocabulary of digital audio, but whatever definition it may have in the vocabulary of analog audio is not the same definition.

This is a deliberate confusion.  The subject of the thread is "...what's the resolution of analog?", which intends to use the term as if it were being used in the vocabulary of digital audio.  The implication in the question is that we know that there is a finite measurable "resolution" in digital audio, so to ask the question in terms of analog raises a moot point, the rhetorical question seems to suppose the answer is "analog is not bound by resolution" or perhaps a repeat of the fallacy that "analog has infinite resolution" or whatever.  It's an apples-to-oranges comparison.

The definition of "resolution" when referring to anything that can be measured in a granular way is very clear to most engineers.  It's simply the amount of difference in absolute change in state that is required to create a binary change in state in the device...  such as the voltage required on an input pin to turn the "0" to a "1".

So I read the original inference in the thread to be an erroneously uninformed rhetorical question, and then a bunch of well-meaning engineers and armchair scientists took the question way too seriously and have engaged in a well-informed but rather silly debate.  It's kind of like if the thread started with "what's the color of 7".  I think the only sensible answer is "no".

Some attempt has been made in this thread to demonstrate some of the merits of analog and explain some of the misconceptions about the analog vs. digital debate, but there's a lot of subjective pseudoscience being thrown around.  

Analog and digital recording aparatus and other devices (effects etc.) use different means to accomplish the same type of goal, and they have different sets of compromises and distortions.  Once you are familiar with one or the other and learn to work around the weaknesses and employ the strengths of one or the other, then that's generally the one you prefer.

Comparing one technology to the other in terms that are only applicable to one doesn't make sense.  So saying "what's the resolution of analog" is a moot question, since analog is not typically considered to be limited by the specification we call "resolution", and to consider only that question without correlating it to weaknesses in the other medium is kind of ridiculous.
Title: Re: George....what's the resolution of analog?
Post by: Eric Rudd on June 03, 2004, 04:47:49 pm
George wrote:

Here's what 'resolution' means to me, and why I've used the word (in fact, have used it for some time, and have been obliged to observe increasingly its misuse)

Resolution is the ability to discern a relatively subtle signal; often this signal of interest is found in the presence of a larger signal, but also perhaps it's only being compared to a larger signal.

~~~~~~~~~~~~~~~~~~~~~~~~~~~

I stare at my keyboard with a million thoughts about this subject flying around in my head, not knowing quite where to start. I do feel that George’s posting is in line with how I use the term resolution in my own experience of audio. But I wanted to expand on his idea of detail…in reverb trails, vocal size, etc.

A few years ago I had the pleasure of listening to some recordings (some hi-fi, some not so) with a blind woman… a blind woman who happened to have some experience with some good audio equipment. She owned an ATR 102, for example.

We would sit there and discuss what we heard in the various recordings. It was a very ear-opening experience, to say the least. I had the door opened to how she heard things…we discussed what instruments or textures or sounds were “on the back wall” of a recording. Its color, texture. “What defines the rear-most dimension in this mix?” Is it a color…reverb trail…or a sound….tambourine? Is there any vertical sound information in this recording? She played me some impeccable recordings done in the rainforests of Australia…where you could determine the elevation of the sounds within the recording.

We discussed what is in the middle ground, the fore ground. We talked about a Bill Schnee mix of a Joe Sample recording…where much of it was in reverb and dark-sounding…which imparted an “under the streetlight at night” mood, as she said.

After years of work in recording, this was a much-needed jump start to my experience with sound. Ed Cherney said once of digital is it’s not the sound of digital that bothered him, it was the “holes” in the sound. And I have identified with this assessment.

Resolution is much more a “visual” thing for me. I am reminded of the George Seurat paintings at the Chicago Art Museum. If you don’t remember, he employed pointillism in his work to generate an image. As you back away from the painting, it takes on a complete form. Move in close and it’s just a collection of dots (essentially).

When digital audio first came on the scene it sounded (to me) like a collection of dots. Not to mention the harsh aspects… edginess, and other artifacts of the early converters, our inappropriately applied analog techniques, etc.

Through the hard work of the industry designers (many of whom are participating in this thread) digital audio has moved away from a pointillist image towards a large format film camera’s image (much like Megapixel cameras are doing now).

Oh yes, I was “pro-analog” and “anti-digital” for a long time. Digital sounded like yuck compared to what I heard through a high quality signal chain (ala, Doug Sax). I was even proud to say that I tried to cut everything I did on analog. For the sound of the signal path, and the effect of analog tape.

But then I heard a record that Erik Zobler did for George Duke a couple of years ago that I knew was all digital that blew my f*&)-ing socks off. I thought to myself that I couldn’t use the anti-digital excuse anymore. I had WORK to do…learn more about this technology, and how to utilize it better.

Thus, I really appreciate all who have contributed to this thread. It has been very educational. I will admit, that while sometimes it was over my head on a design level, I did my best to hold on for dear life and learn something.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
George wrote:

In digital, it's clear that when we started doing more accurate conversion, and more capable dithering, that we absolutely heard a difference in resolution. And you know what I mean - forgive me...I simply don't know what else to call it.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Exactly. We are looking at a George Seurat painting…but now we can move in much closer…because the image is strong enough and cohesive enough and has detail enough between the dots to withstand closer scrutiny.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Nika said:

The problem is clearly that people make the correlation between statistical resolution of digital systems with the subjective resolution of audio. Thus, I think it is reasonable to simply not use the term when describing the bit depth or sample frequency related issues of digital systems.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This is because those of us who aren’t designers were looking for a reason why things sound to us the way they do. I know that I heard a difference from digital audio, and chose to find out why. I hear a difference between 16 bit and 24 bit. When I went looking for a reason why digital was sounding better, this seems to be one of the contributing factors. I’m sure there are others…converter quality improving, 87 bit sinking point math, etc. I’ll address these and other things as time (and my learning curve) allows.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Nika said:

I have avoided bringing this up until now simply to avoid further confusion regarding the term. I have no objection at all to people saying that something has "more resolution," but unless it has more euphonic "detail"  <snip>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I’m with you there. I see our application of the term is similar….oh wait…there’s more to your posting..  Surprised)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Nika continues:

or greater instantaneous dynamic range in a floating point system I posit that their use is incorrect and draw the conclusion that they have a discorrelation regarding digital audio that I referred to earlier.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

What I really don’t quite get about this thread is why people are getting there noses in a scrunchy about definitions. If a designer uses a particular word that happens to mean one thing in his world, but it means something different to me…oh well. One definition of resolution reads: “The fineness of detail that can be distinguished in an image”  Nika’s explanation of the 126db of dynamic range of a system as its resolution seems incorrect to me. You should call it bandwidth, or brackets, or …gasp… range?

The end result is a sound image. Air moving. Tomato…tomahto.  Fineness of detail sounds pretty darn close to how I use the word resolution. If the mathematicians use it for something else, more power to them. But when the listener says something sounds like crap, best to drop the hair splitting and figure out how to make it better.

Eric Rudd
Title: Re: George....what's the resolution of analog?
Post by: Nika Aldrich on June 03, 2004, 05:42:52 pm
Eric Rudd wrote on Thu, 03 June 2004 21:47

What I really don?t quite get about this thread is why people are getting there noses in a scrunchy about definitions. If a designer uses a particular word that happens to mean one thing in his world, but it means something different to me?oh well.


Because words are used for communication - to communicate messages.  If two people use one word differently then when they speak the message that is encoded with the words will not get through.

Quote:

One definition of resolution reads: ?The fineness of detail that can be distinguished in an image?  Nika?s explanation of the 126db of dynamic range of a system as its resolution seems incorrect to me. You should call it bandwidth, or brackets, or ?gasp? range?


But that is a very real use of the term in the floating point mathematics world and has been in use for some time.  Neither of these definitions are "wrong" at all.  When we talk about this stuff we need to keep our words straight to communicate effectively.  The real problem comes in when people start talking about bit-depth in terms of "resolution."  Bit depth neither directly relates to the depth-detail definition of resolution nor does it relate to the instantaneous dynamic range definition.  The public communication of this, however, has people believing that a change in bit-depth inherently creates an increase in detail, which is a complete fallacy.  It simply becomes a poor word to use in those circumstances.  It does not effectively communicate and instead indicates that the user has a level of misunderstanding.

Quote:

Fineness of detail sounds pretty darn close to how I use the word resolution.


Just be aware that changing bit-depth does not inherently increase your "resolution" as you and many others use the term.

Nika.
Title: Re: George....what's the resolution of analog?
Post by: Eric Rudd on June 03, 2004, 05:56:57 pm
[/quote]

Just be aware that changing bit-depth does not inherently increase your "resolution" as you and many others use the term.

Nika.[/quote]

Hmm....I'd like to see how this thread pans out, then.

Eric
Title: Re: George....what's the resolution of analog?
Post by: jfrigo on June 03, 2004, 06:09:36 pm
Eric Rudd wrote on Thu, 03 June 2004 21:47

You should call it bandwidth, or brackets, or ?gasp? range?


Except that "bandwidth' already has a definition in the frequency domain. I think it should be easy to differentiate between the two ways of referring to resolution by just makig it clear which form you are using. Perhaps one could use an adjective like "measured" when talking about it as an engineering term related to digital audio, or something like  "aural" or "perceived" when speaking of the detail you are actually hearing. I don't think the dual uses are going away any time soon, yet communication is clearly impaired when one doesn't make clear how one is using the term, so I think simply a little forethought when writing or speaking would ease communication, if not necessarily understanding.

Title: Re: George....what's the resolution of analog?
Post by: ted nightshade on June 03, 2004, 08:27:07 pm
I don't see resolution as a either-the-system-has-it-or-not proposition- I see it as a characteristic of a specific recording that you could lose some amount of at any moment by almost any process or by introducing any component into the chain. It's something you have to listen for, be aware of, and make a point of capturing and preserving, if such things are an over-riding concern. I don't think "euphonic" is really too apt of a term to use in all cases concerning resolution- sometimes, you don't want to hear some of that stuff- It's more than you care to know! Like a good close up of the pores on a lovely woman. Or you might like that kind of thing. (have you ever really looked at your hand?Wink But sometimes, yes, a perceived increase in resolution can be the result of distortion that creates heightened textures and calls certain details to attention that otherwise might be not as obvious- but this can be selective and might obscure completely other details of the sound, so this kind of "euphonic" resolution increase might not represent an actual increase in resolution (you can discern more details of the source than you could before), but an apparent increase.

If it sounds better, it's "euphonic"- (a term that carries not a little disdain the way some people use it sometimes) but an increase in resolution doesn't necessarily sound better. Some times a decrease in resolution is more pleasing, but for very complex signals you need absolutely every bit of resolution you can get and then some. No recording of Bartok, no matter how good, and there are some truly great ones from the late 50's on, prepared me for sitting in the front row and hearing every individual violin and viola scratching away frenetically from a distinct spatial location, in a distinct individual voice! We're a long ways from being there.
Title: Re: George....what's the resolution of analog?
Post by: Paul Frindle on June 03, 2004, 09:25:57 pm
Nika Aldrich wrote on Thu, 03 June 2004 22:42

Eric Rudd wrote on Thu, 03 June 2004 21:47

What I really don?t quite get about this thread is why people are getting there noses in a scrunchy about definitions. If a designer uses a particular word that happens to mean one thing in his world, but it means something different to me?oh well.


Because words are used for communication - to communicate messages.  If two people use one word differently then when they speak the message that is encoded with the words will not get through.

Quote:

One definition of resolution reads: ?The fineness of detail that can be distinguished in an image?  Nika?s explanation of the 126db of dynamic range of a system as its resolution seems incorrect to me. You should call it bandwidth, or brackets, or ?gasp? range?


But that is a very real use of the term in the floating point mathematics world and has been in use for some time.  Neither of these definitions are "wrong" at all.  When we talk about this stuff we need to keep our words straight to communicate effectively.  The real problem comes in when people start talking about bit-depth in terms of "resolution."  Bit depth neither directly relates to the depth-detail definition of resolution nor does it relate to the instantaneous dynamic range definition.  The public communication of this, however, has people believing that a change in bit-depth inherently creates an increase in detail, which is a complete fallacy.  It simply becomes a poor word to use in those circumstances.  It does not effectively communicate and instead indicates that the user has a level of misunderstanding.

Quote:

Fineness of detail sounds pretty darn close to how I use the word resolution.


Just be aware that changing bit-depth does not inherently increase your "resolution" as you and many others use the term.

Nika.


The answer is quite simple IMVHO, but it always escapes people in our modern culture - it's the misuse of language. This is becoming increasingly popular as 'market speak' hijacks and engulfs our whole communication idiom (and it's extremely dangerous IMHO!).

The problem is that the word 'resolution' REQUIRES a qualifier in the english language. I.e. the resolution of something.

George mentions the resolution (i.e. the ability to resolve) audio signal properties. Others mention the resolution of the math in the sampling domain (i.e. the ability to resolve quantities). Some others refer to the resolution in the timing domain (i.e. the ability to resolve timing information). People refer to the resolution of placement in stereo reproduction systems (i.e. ability to resolve positional information). All of these are perfectly reasonable and explanatory (even if sometimes misguided), becasue they are qualified and defined.

However 'resolution' on its own is a floating and unqualified concept that invites speculation and defines nothing. Just the job for people selling 'newness' as an undefined concept - lots of which we see going on in all sectors of the marketing of everything from Cornflakes to Cars. We can think of any number of such terms that have been invented to induce a 'general concept' to products, without qualification (and therefore without possibility of legal challenge).

Now if we talk of 'high resolution audio' (as I have actually seen mooted even in academic papers - even more dangerous!!), we absolutely MUST define what this exactly means - or else it actually means zilch - nothing!

So a question like "what's the resolution of analogue" has to be answered by another question, "to which aspect of an analogue signal are you refering?"

THEN we have a valid discussion Smile

So then:

"Whats the quantity resolution of a digital system?"

No numerical representation can in itself have complete quantity resolving power (i.e. an infinite number of decimal places). The addition of dither turns this unavoidable inaccuracy into noise. The level of the noise is related to the number length of the signal - and that's all. The resulting signal has no quantity resolution limit - only S/N ratio (almost true practically).

"What's the timing resolution of a digital signal?"

That depends on the efficiency of your anti-aliassing and reconstruction filters (both analogue and digital). If they are complete then there is infinite timing accuracy (almost achievable practically).

"Whats the phase resolution of a digital system?"

See above. With perfect filtering the phase resolution of any signal in the pass band is complete.


"Whats the frequency resolution of a digital system?".

The max freq you can have is something just less than half the sampling rate. All possible freqs within this range are equally represented.

"What's the reproduced signal freq absolute accuracy?"

That depends on your sample rate timing accuracy.


Now which one of these factors are we relating to an analogue signal path? Smile
Title: Re: George....what's the resolution of analog?
Post by: George Massenburg on June 03, 2004, 10:17:48 pm
Nika Aldrich wrote on Thu, 03 June 2004 16:42

Just be aware that changing bit-depth does not inherently increase your "resolution" as you and many others use the term.

Nika.


Incorrect.  

Well, in the well-intentioned converter (one that intends to deploy real "resolution" with meaning to it's claims), it should, and at least some of the time it actually can and does.

Stop being a contrarian, Nika, it's not going to look good from the perspective of history.

George
Title: Re: George....what's the resolution of analog?
Post by: Nika Aldrich on June 03, 2004, 10:51:22 pm
George Massenburg wrote on Fri, 04 June 2004 03:17

Nika Aldrich wrote on Thu, 03 June 2004 16:42

Just be aware that changing bit-depth does not inherently increase your "resolution" as you and many others use the term.

Nika.


Incorrect.  

Well, in the well-intentioned converter (one that intends to deploy real "resolution" with meaning to it's claims), it should, and at least some of the time it actually can and does.


Note the highlighted word above.

Quote:

Stop being a contrarian, Nika, it's not going to look good from the perspective of history.


Believe me: the least of my concerns.

Nika.

P.S.  A contrarian?  I AM NOT!!!!!  Smile
Title: Re: George....what's the resolution of analog?
Post by: Eliott James on June 03, 2004, 11:31:16 pm
So can we measure the detail of analog?
Title: Re: George....what's the resolution of analog?
Post by: dwoz on June 04, 2004, 12:41:44 am


I think the real issue here is "what's the resolution of Nika?"


ya say ya want a resolution
well, you know
we all wanna see the plan


dwoz
Title: Re: George....what's the resolution of analog?
Post by: djui5 on June 04, 2004, 02:07:17 am
Thanks all for the answeres to the "will there ever be a defenition for resolution" question.

Even though there are still people commenting on the subject, I've come to the conclusion that the definition of resolution is in the eye of the beholder and a "set in stone" definition will never happen.

Interesting.
Title: Re: George....what's the resolution of analog?
Post by: Curve Dominant on June 04, 2004, 03:59:37 am
Quote:

Even though there are still people commenting on the subject, I've come to the conclusion that the definition of resolution is in the eye of the beholder and a "set in stone" definition will never happen.


There is always room for subjectivity.

Just as long as that is what it is recognized as: Subjective.

I will not take anything away from the philosophical merits of the term "resolution" as it applies to audio, or anything else for that matter.
Title: Re: George....what's the resolution of analog?
Post by: xAm on June 04, 2004, 07:00:01 am
Sorry to be chiming in here so late... kinda' busy at the day gig...

VERY interesting thread.

Maybe I missed something or someone's point while reading, but I think the resolution issue is very definable in terms of what the original question was.

My day gig is imaging. Especially digital imaging... about 1 million digital images a year. If I stay at the day gig, (God I hope I can break out!), I will be designing and implemmenting a system to handle 3.5 million PLUS images. So I get to deal with resolution issues all *&% day!

A point was touched on very early in the thread but I didn't see anyone pick up the point and run with it. To me it's simply restated; What is the smallest measurable quantity of audio frequencies in analog vs digital. e.g the smallest quantized information of a given system. Not the highest frequency of the system.

While I won't pretend to know the numbers here, I think the answer is answerable in some concrete numbers...

To make this a valid "resolution" argument that can be analyzed, lets pick say 3 frequencies; 20Hz, 1kHz and 20kHz.

Next let's pick two (or three) volumes, or densities of sound, say... -20db and +3db... maybe -10db too?

First the "formula" for analog;
What is the MINIMUM measurable density of flux that can be transferred to tape at each of the frequencies and then the maximum. (and maybe a "nominal" mid-range value)

Repeat for digital.

One should now be able to graph the results in comparative analysis. This will be resolution range.

Resolution in imaging is accepted to indicate the smallest measuable unit. However, it has recently come to be scrutinized as having a secondary component of accuracy. e.g. how faithful is detail captured.

An image is comprised of  shades (variations) of density on a given pixel. The pixel, remember, is JUST a picture element. By definition a pixel has no size until it is converted to a physical entity.

It, faithful reproduction, becomes a resolution issue in that at either end of the brightness "scale" or density curve, how accurate (measurable) is a given device in quantizing these densities, thereby resulting in a realistic (subjective) reproduction of the subject matter.

Hmmmmm, gee this sounds exactly like what we're dealing with here in the digital vs analog audio world doesn't  it?

What suprises me though, is that as yet I haven't come across any recent hard data showing this kind of comparative analysis. Then again, I haven't  had time to really dig for it in terms of audio.

In imaging, the way we test the accuracy is to use a "Shirley" and/or a test image. It is an image or a physical item that is comprised of "known" values. One company that produces these items is Gretag-Macbeth; http://www.gretagmacbeth.com/print/index/products/products_c olor-standards/products_colorchecker-charts/products_colorch ecker-sg.htm The way we use this type of "chart" is to photograph it at an extreme under-exposed, normal and an extreme over-exposed setting. The image is then processed and the resultant image is processed and compared to the actual physical image by spectrum analysis (measured) and by consensus (subjective).

The reasoning is that color accuracy is measurable, but only at the normal exposure. On the over and under images, the overall contrast from one patch to another is subjective. Is it believable? Another "tool" we use is to photograph a blonde, brunette and redhead at the same under, normal and over exposed settings. We then look at the detail in the hair. How accurate is the skin tone, shadow detail and highlight detail? While subjective in nature, a consensus is developed 100 percent of the time.

My point is that indeed there are ways to determine the resolution of analog just as there are ways to measure the resolution of digital.

Does anyone have these number or the ability to perform any of these tests? I for one would really like to see the numbers and results.

Max
Title: Re: George....what's the resolution of analog?
Post by: josh on June 04, 2004, 09:58:51 am
xaMdaM wrote on Fri, 04 June 2004 12:00


First the "formula" for analog;
What is the MINIMUM measurable density of flux that can be transferred to tape at each of the frequencies and then the maximum. (and maybe a "nominal" mid-range value)

[snip]

Resolution in imaging is accepted to indicate the smallest measuable unit. However, it has recently come to be scrutinized as having a secondary component of accuracy. e.g. how faithful is detail captured.



But you see, now you are getting into the fuzzy part of this whole thing.

If you define "resolution" this way, and stack on top of it "accuracy", then statistically you can only count resolution as meaningful if it is accurate.  Looking at it from a mathematical point of view, simplistically we know that if you have two measurements that are accurate to two decimal places and you multiply them, you have a resultant number that may contain four decimal places of precision, but the last few decimal places are junk...  they are not accurate because they result from an infinitely precise math function produced from rounded or truncated numbers.

So let's say you determine that the "resolution" (whatever way you want to measure it...  we don't even have an agreed-upon unit of measure so let's say it's measured in "whatzits") of analog is 10 whatzits, and the resolution of digital at 24bit/96kHz is 20 whatzits.  That is to say, the minimum change in dB/whatzit that is required to change the state of the media some measurable unit on analog tape is 1/2 the dB/whatzit that's required to change the state of the data output from an ADC 1 by 1 bit.

Now you must quantify the error rate, or determine the accuracy, and agree upon a minimum error rate that is considered "accurate".  In broadband communication circuits, for example, we consider 1 error in 10^7 bits to be "accurate", and an error rate greater than that is considered to be unacceptable.  So to do this test, you would have to perform a series of writes/reads to the media in both cases (analog and digital), at a graduated level of granularity of "whatzits"...  so you'd do say 10 billion writes/reads (in order to get a statistically significant number of errors to extrapolate the error rate) at 10 whatzits, then at 11, then at 12... etc. until you can recognize the "corner", or the point at which the error rate is substantially under the limit so you can consider it "accurate".  This is then your real measurement.

Now, taking into account, say, only the tape and tape head, and only the input to the ADC and the output data registers, neglects the rest of the system which produces error.  If we were to make an analogy for imaging, which you are familiar, consider if we were to do the imaging analysis through a telescope...  because in essence we have similar analog circuitry (amplifiers) ahead of the tape head and ADC input which introduce their own distortions and errors.  Now in order to determine the "resolution" in whatzits, we have to measure it in an absolute manner through the common amplifier and other analog circuitry (cabling, connectors, solder joints, resistors, etc...).  This further reduces the "whatzits" for both media types.

The thing is that these distortions and errors, which will occur randomly at some degree and become less random and more rare as you approach the "knee" of the curve for accuracy for whichever media, are present in the playback and clearly audible.  So you may perceive a recording as more detailed or as having greater "resolution" simply because it has a greater amount of information in the category you define as "resolution" or "detail", but without reference to the actual source or the accuracy of that detail.  In this sense you can think of "detail" as being more like "precision".  Perceived detail in a recording that you are playing back does not correlate necessarily to greater resolution of the aparatus that made the recording...

For a simplistic example, if I remove the capacitor from the tweeter crossover in a speaker and play back music on it, you are going to perceive a higher degree of harmonic content in the upper midrange of everything I play on it.  This may translate to a sense of greater midrange "texture" and "detail" and certainly a more forward midrange that makes certain sounds "jump out" at you, so you may find this imparts a greater sense of spatial detail as well.  However it's hyped and distorted.  This extra "detail" is actually just an extra amount of error that happens to occur in a way that we perceive as some kinds of "detail", but it's not actually more detailed, and does not mean there is greater resolution in the recording...  It is a euphonic distortion plain and simple.

So Nika is right...  we need to be sure we are not confusing euphonic distortion aka "detail" as audiophiles would call it with real resolution.  

I still think this is a misguided discussion altogether, ignoring the glaring and obvious differences between analog and digital and instead preferring to examine the minutia hoping to find some engineering proof that analog is better.  If it sounds better to you, then it is, right?  So who cares if you prefer it because it's distorted?  Who cares if digital is measurably better but you still don't like the way it sounds?  "Accurate", "Detailed" and "High-resolution" are not always preferable.
Title: Re: George....what's the resolution of analog?
Post by: George Massenburg on June 04, 2004, 01:59:46 pm
xaMdaM wrote on Fri, 04 June 2004 06:00



[...]

My point is that indeed there are ways to determine the resolution of analog just as there are ways to measure the resolution of digital.

Does anyone have these number or the ability to perform any of these tests? I for one would really like to see the numbers and results.

Max


Well, at worst that's wishful thinking.  I think from what you read on this thread from some very well-informed, competent engineers is that there is really no numerical analysis tool for "resolution" beyond what is purely a technical specification of the performance of A/D converters.

What, in your opinion, would a "perception-sensitive" resolution test look like?

Geez, I wish audio/music/hearing were as clear-cut as video/pictures/seeing.

George
Title: Re: George....what's the resolution of analog?
Post by: dayvel on June 04, 2004, 02:45:57 pm
Quote:

Geez, I wish audio/music/hearing were as clear-cut as video/pictures/seeing.


And the movie guys discussing film/digital imaging wish that their stuff was as clear-cut as audio/music/hearing.
Title: Re: George....what's the resolution of analog?
Post by: Nika Aldrich on June 04, 2004, 06:25:35 pm
Max,

A point worth bringing forth is that video/photo and audio are inherently different in that digital images are sampled and then stay digital, all the way through the delivery stage.  The photo does not, for example, undergo a "reconstruction" stage that turns it back into an analog photograph.  What gets printed on silver paper and delivered to the eyes of the consumers is still a pixilated digital image.  In that respect we can discuss the resolution of the photograph simply by discussing the photograph in its pixilated (and only) form.

In audio the pixils, or samples, are only representations of the complete product.  The complete product has to get reconciled from the samples, undergoing a reconstruction process to determine the actual analog waveform that is represented by the samples.  Because of this, discussing the resolution of the samples can be unhelpful because we really need to discuss the effect on the resultant waveform.  In digital photos this is again not an issue -the samples ARE the end result.  In digital audio the samples only REPRESENT the end result.  It is important that we discuss things in digital audio by discussing the effect on the net result - the product that is REPRESENTED by the samples, and not so much on the samples themselves.  In digital photos you can change all of the samples in some way and we can still discuss that in terms of resolution.  In digital audio you change all of the samples in some way and we now have to use other terms to talk about the net result on the resultant waveform - we may talk about it in terms of distortion, or dynamic range, etc.

Does that make any sense?

Nika.
Title: Re: George....what's the resolution of analog?
Post by: djui5 on June 04, 2004, 07:31:16 pm
George Massenburg wrote on Fri, 04 June 2004 11:59

What, in your opinion, would a "perception-sensitive" resolution test look like?



A bunch of engineers in a control room listening to playback....
Title: Re: George....what's the resolution of analog?
Post by: Paul Frindle on June 04, 2004, 07:45:10 pm
Nika Aldrich wrote on Fri, 04 June 2004 23:25

Max,

A point worth bringing forth is that video/photo and audio are inherently different in that digital images are sampled and then stay digital, all the way through the delivery stage.  The photo does not, for example, undergo a "reconstruction" stage that turns it back into an analog photograph.  What gets printed on silver paper and delivered to the eyes of the consumers is still a pixilated digital image.  In that respect we can discuss the resolution of the photograph simply by discussing the photograph in its pixilated (and only) form.

In audio the pixils, or samples, are only representations of the complete product.  The complete product has to get reconciled from the samples, undergoing a reconstruction process to determine the actual analog waveform that is represented by the samples.  Because of this, discussing the resolution of the samples can be unhelpful because we really need to discuss the effect on the resultant waveform.  In digital photos this is again not an issue -the samples ARE the end result.  In digital audio the samples only REPRESENT the end result.  It is important that we discuss things in digital audio by discussing the effect on the net result - the product that is REPRESENTED by the samples, and not so much on the samples themselves.  In digital photos you can change all of the samples in some way and we can still discuss that in terms of resolution.  In digital audio you change all of the samples in some way and we now have to use other terms to talk about the net result on the resultant waveform - we may talk about it in terms of distortion, or dynamic range, etc.

Does that make any sense?

Nika.


You are correct in saying that the image situation is different in that the result of the system remains pixelated - thats a good point. And in fact digital audio would also be delivered level quantised of it were not correctly filtered (please remember very crucially that the final stage of the filter must be ANALOGUE(!) in order to avoid all quantisation artefacts). But there are still some parallels in these two mechanisms worth thinking about:

Now if we talk about detail resolution in pictures it does have real meaning. For instance the resolving power of film is determined by the molecule sizes in the emulsion. These are not uniform and there tends to be a Gaussian dispersion of the sizes (i.e. it is kind of self-dithered in a positional sense). This is a bit like (but not completely) a digital system with a randomly changing sample rate which is synchronous throughout and gaussian in distribution (there's an idea I have thought about lots years ago and even tried). However the total resolving power of the film can still be likened to frequency response, in that any detail in the picture that tries to be finer than ANY of the molecules in the emulsion will not be reproduced - and will only contribute to the brightness information of larger pixels in that area.

Where a picture is reproduced on a digital screen with uniform and defined pixels the situation is different and in fact several possibilities of error exist that are more like a digital audio system. The most obvious is that the edges of the pixels (either in the camera or the screen) can be sharper than the bandwidth of the data used in the picture - actually giving the impression of higher detail than available in the original image. This is particularly true if detail in the image corresponds to recognisable and inherantly aligned components like typing fonts, squares and straight lines.

Now (ignoring the 2 dimensional issues) this is the equivalent of aliassing error in that the bandwidth and harmonics of the reproduced picture are greater than (and may not have come from)the original image data. I.e. quantisation distortion Smile

This is equivalent to say a DAC converter with insufficient filtering. The signal caused by the initial quantisation reaches the output. It is an illegal signal and it is then up to the following Amps, Speaker and Ears to make what it will from the error Sad

Now if we look closer at the screen (and camera) quantisation we can see that if we wanted to remove the quantisation of the pixels statistically from the whole system, one method (rather than simply trying for infinite numbers of pixels) would be to shake them around at random physically whilst holding the actual image position constant wrt to the viewer. In this way all positional possibilities for the optical image would be serviced at one time or another. All quantisation would be removed from the imaging system and be replaced by amplitude noise. That is equivalent to what dithering does to digital audio - the quanitsation of the signal due to limited bits is removed and replaced by amplitude noise which has (hopefully) no relation to the signal itself Smile

This seems like a long winded explanation of how these arguments could be combined (if we define the nature of what the 'resolution' word refers to) - but hopefully it may make some sense?
Title: Re: George....what's the resolution of analog?
Post by: xAm on June 04, 2004, 10:36:22 pm
Nika,

Yes you make sense! I only hope that my follow-up does as well...

I woke up at 4:30 this morning and found this thread. When I realized that I was about to be late for work, I closed off and didn't really have time to finish my point. I hate leaving a thought dangling...

Now to continue my thought... (as dangerous as that is!)
Quote:

Resolution in imaging is accepted to indicate the smallest measurable unit. However, it has recently come to be scrutinized as having a secondary component of accuracy. e.g. how faithful is detail captured.


This makes for dicey discorse to say the very least.

Josh very graciously continued on to the path I was heading... (only  with more intelligent and accurate nomenclature!... I think that's the word I'm looking for...)

Quote:

If you define "resolution" this way, and stack on top of it "accuracy", then statistically you can only count resolution as meaningful if it is accurate. Looking at it from a mathematical point of view, simplistically we know that if you have two measurements that are accurate to two decimal places and you multiply them, you have a resultant number that may contain four decimal places of precision, but the last few decimal places are junk... they are not accurate because they result from an infinitely precise math function produced from rounded or truncated numbers.


PRECISELY MY POINT!!! At least I was at that coherent at 6am!

As I may not have adequately stated it; Resolution is a process of determining the smallest measurable quantity of meaningful information.

So while it is possible to determine the resolution of analog, it is only a VALID quantity when it's comparative using known absolutes. This is equally valid for digital. One CAN establish a comparison of analog to digital in both audio and in imaging... please hold the beer bottles you want to throw at me for a moment... but ONLY when valid absolute baseline values of input are established.

In imaging, there is an emulsion that is comprised of silver halide riding on a substrate. The equivalent to iron oxide on mylar. These are known physical states. The "resolution" is determined by subjecting the "media" to known quantized information. The smallest amount of transfered information that results in measurable changed states is the resolution.

It is only at this point that a measurement of resolution can be initially performed.

In our analog audio model, that would be the measurement of the magnetic quantization of oxide on the substrate. Again, the resultant latent information would have to be obtained from measurement of the input to latent information ratio.

To complete the loop, one must repeat the entire process in reverse for playback.

If one want to pick "nits" then nits' are all that you can deal in. If you pick angstrom's to measure against, then a single photon is your baseline. If you pick db your baseline is what?  electron volt/mS??

If we can agree on a quantitative value for input and the ratio for the measurement of transfer of information, then a reasonably accurate comparison can be done that may actually be meaningful.

It's when you step outside these very precise controlled situations that the whole point becomes moot. (Now just how often do we step outside a controlled environment?!?) More accurately... when the hell are we ever in one!?!

The resolution CAN be determined for analog. Just as it can for digital. A comparative analysis CAN be done. And I for one would like to see the iterations of samplings in graphical form. It might be a really decent challenge for an AES candidate to do a paper on... provided s/he had access to a highly controlled laboratory environment to test in.

I'm sure that the results would surprise everyone! (I have no theory or preclusion as to what the results would be.)

Sorry I didn't have the time to point out that it wouldn't be easy, cheap or even valid for much more than one, two or even three given frequencies at best. It could most likely only be valid for the individual machines that the test was performed on... My "point" is only that it CAN be done.

The truth of the matter, as has been thoroughly and heatedly discussed here and all across the industry, is the qualitative end result that is entirely subjective.

In photographic imaging the exact same "reality" is being debated. So don't feel like this is the only industry forced into this debate. In printing and graphic arts we went through this 15 years ago. Hell, we went through this in medical imaging over 25 years ago! Why doesn't it go away? People like to argue I guess.

The "battle" seems to have been pushed into a which is "better" question. Neither and both in my mind.

I was just trying to figure out an answer the guys question.

Max
Title: Re: George....what's the resolution of analog?
Post by: ted nightshade on June 04, 2004, 11:47:57 pm
Nika, Paul, xaMdaM-

great stuff! It would be very useful to have a way of measuring resolution in regards to what kind of detail could be captured- what is the audio equivalent of the redhead, the blonde and the brunette? For me, there are certain known cymbals, handhammered and hand lathed, that put out such an unfathomably complex tone- this is a benchmark that gives me a sense of the resolution of a recording made of that cymbal. All that detail is audible in the room when other instruments contribute as well- the cymbals clear up there where it really has it's own airy realm to itself.

And of course the mic placement is a big factor... far fussier than the human ear.

Is there some way to feed a system something suitably and measurably complex, as complex as music, far more complex than any test tone- noise with dynamics? Is there something we could use to measure the resolution of a system in the terms xaMdaM puts forth above- the system can capture this but it can't capture that? No system will be able to capture it all, if the feed is anywhere near as complex as a jazz combo.

The idea intrigues me- I'm not the geek for the job, but this kind of thing in the service of the technical side of art seems to have definite potential to me. A meter you can read- OK, we put this signal through some unity gain non-process or bypass, but a different digital or analog patch- did the resolution change? Or we are trying to change the signal, but preserve some degree of resolution- what's the meter say? There would be no "correct" setting, any more than there is for a VU meter. But I think resolution is at least as relevant as noise floor, bandwidth, or any other measurable attribute.

I'm dreamin', I know, but what a good discussion this has become in the last few posts...
Title: Re: George....what's the resolution of analog?
Post by: Curve Dominant on June 05, 2004, 01:57:09 am
Quote:

posted by Paul Frindle:
Now if we look closer at the screen (and camera) quantisation we can see that if we wanted to remove the quantisation of the pixels statistically from the whole system, one method (rather than simply trying for infinite numbers of pixels) would be to shake them around at random physically whilst holding the actual image position constant wrt to the viewer. In this way all positional possibilities for the optical image would be serviced at one time or another. All quantisation would be removed from the imaging system and be replaced by amplitude noise.


Paul,

In PhotoShop, there is a filter which does this, called Unsharp Mask. It is a digital emulation of  a darkroom technique, as it happens.

It's quite simple:

On one layer, the program isolates contrasting pixels, and amplfies the contrast, to user specification.

On the second layer, it blurs those contrasting regions in a Gaussian fashion (hence "Unsharp Mask"), to user specification.

The program then overlays the two effects.

The combination of the blurred image with the sharpened image, creates the desired effect. The trick is in the proper mixing of the sharpening and the blurring, and fine tuning the two so they work together optimally.

As in audio?? ...kinda, sorta, but not really. My experiences with photography have not lent well to parallels with audio in regards to this "resolution" issue. Photography has inherent variables which exist outside the audio paradigm, and vice-versa.

Title: Re: George....what's the resolution of analog?
Post by: JDSStudios on June 05, 2004, 06:41:50 am
We could perhaps define audio analogue "resolution" as the difference, or lack of, between the recorded signal and the live natural audio.

We could have a scale, with its maximum value when there would be no measurable or perceivable difference between the original live audio, and the recorded audio.

Moving on down this scale, we could have all other degenerative elements, like distortion, noise, jitter, etc., or any modifier of the original sound.

John Ferreira
JDS Recording Studios
Title: Re: George....what's the resolution of analog?
Post by: josh on June 05, 2004, 09:10:39 am
JDSStudios wrote on Sat, 05 June 2004 11:41

We could perhaps define audio analogue "resolution" as the difference, or lack of, between the recorded signal and the live natural audio.



If we did, then it would become a completely useless term, because there is simply no way to make a meaningful comparison.  

One problem with this whole debate is that whatever we are comparing has to be measurable in some way.  So if we isolate the problem deeper into the system...  the tape head amp input to tape playback head amp output vs. the ADC input to the DAC output for example, then provided we have a controllable, repeatable and measurable way of injecting a signal into both devices (assuming we can come up with a representative signal), we can make a comparison.

However, if we insert a mic preamplifier in between the signal genreator and the device under test, then the mic preamplifier itself becomes the device under test, or at least it becomes an important limiter of the performance of the device under test.

Further, if we insert an actual microphone, certainly any production microphone is so overtly distorted, especially considering placement, interaction with the preamplifier, etc., that the microphone itself would become the dominant feature in the whole system under test.  In order to produce a repeatable audible event for a test like this, we would have to do it with a loudspeaker, an amplifier, and then the signal generator on the front end of the amplifier.  In this scenario far and away the dominant feature of the test is the loudspeaker.  

So, using actual auditory information (a real sound you can hear), we cannot conduct a meaningful test regarding the resolution of a recording device.  

A recording device such as a digital recorder or an analog tape machine does not actually receive audible sound as input.  It receives a time-varying voltage as input.  The only meaningful measurement of a device like this is to measure it with respect only to the accuracy and precision of the recording and playback of the time-varying voltage.  Input a known signal (some kind of broadband, transient, etc., agreed-upon signal source), record it, then play back the ouput, and compare it to the original signal.

Intuitively we know the answer to this question though.  If we take a digital recorder and record something on it, and consider that recording to be the "control", and then play that and record it to analog tape, and use the very same digital recorder to record the playback from the tape and "diff" the files, we can readily see the distortion caused by the analog tape.  You will have added to this the distortion caused by the digital recorder since it is both recording and playing back.

If you repeat the test with another identical digital recorder, then your analysis of differences will have compounded the distortions of the digital recorder.

This is a crude test and completely unreliable because our test equipment is the same equipment as our device under test.  It is impossible to measure the nonlinearity of a digital recorder by analysing it using an identical digital recorder.

However, it may be that much of the most accurate audio measuring equipment we have access to is the very digital recording equipment we would like to measure.  I don't know because I have not investigated digital capture equipment for audio other than that used for recording.  If there were measuring equipment capable of determining this difference, then it means that somewhere there exists a recording and playback device that is orders of magnitude more precise and more accurate than even the high-end recording gear that we would like to test.  I don't know if this exists.

Again, though, this all is a moot point because no sane audio engineer is going to try and make a rational argument that analog tape recording is more accurate and more precise in a measurable sense than digital recording.  The arguments for analog start with "it sounds better" but never with "it's much more accurate and precise".  We know that analog tape is colored (distorted) and we like it that way.  Back to my original point when I joined this thread:  audio recording is not about "resolution", "accuracy", "precision", "frequency response", or any other measurable thing...  our current state-of-the-art in both analog and digital is way beyond what is required in these categories.  When we record, we intentionally distort the recordings because audio is all about perception, and human beings are extremely non-linear perceivers and processors of auditory stimuli.  Making an accurate, linear recording will not result in one that is lifelike to listen to!  To make a lifelike recording requires distortion.  We would do better to focus on exactly what type of distortion is beneficial to making lifelike recordings, rather than the meaningless argument over the minutia of what does not make a real difference.

Title: Re: George....what's the resolution of analog?
Post by: ted nightshade on June 05, 2004, 10:56:30 am
Good points Josh.

josh wrote on Sat, 05 June 2004 06:10

 audio recording is not about "resolution", "accuracy", "precision", "frequency response", or any other measurable thing...  our current state-of-the-art in both analog and digital is way beyond what is required in these categories.




I disagree, strongly indeed. There's nothing out there that can do any kind of justice to a nice handmade cymbal, not in resolution, not in accuracy, not in precision, probably not even in frequency response.

Quote:

When we record, we intentionally distort the recordings because audio is all about perception, and human beings are extremely non-linear perceivers and processors of auditory stimuli.  Making an accurate, linear recording will not result in one that is lifelike to listen to!  To make a lifelike recording requires distortion.  We would do better to focus on exactly what type of distortion is beneficial to making lifelike recordings, rather than the meaningless argument over the minutia of what does not make a real difference.




An excellent point indeed- some distortion destroys the illusion, in much tinier quantities than some of the distortion that can aid the illusion. Some of it needs to be eradicated, some needs to be put into service if and when it helps.
Title: Re: George....what's the resolution of analog?
Post by: Nathanael Iversen on June 05, 2004, 01:38:22 pm
josh wrote on Sat, 05 June 2004 14:10

  When we record, we intentionally distort the recordings because audio is all about perception, and human beings are extremely non-linear perceivers and processors of auditory stimuli.  Making an accurate, linear recording will not result in one that is lifelike to listen to!  To make a lifelike recording requires distortion.  We would do better to focus on exactly what type of distortion is beneficial to making lifelike recordings, rather than the meaningless argument over the minutia of what does not make a real difference.


I for one, want a recording that is accurate, linear and completely without distortions.  Folk like Nelson Pass and John Dunlavy have spent their entire careers trying to offer that on the reproduction side.  If distortion is not part of the original event, I can see no reason it would be necessary to recreate the event.  

That is like saying, there was no purple in the sunset, but to have the same visual effect in the photograph, I am adding in purple.  Irrational.  Purple may be a cool color, it may even make the picture more emotionally invoving.  But having your camera automatically insert purple into the photo is a distortion.  What happens when you want a picture of a white wall?  Is the purple tinged camera still as useful?

I think you could say that all recordings have distortions - technology is imperfect, but it is a big leap to say that all recordings NEED distortions and we ought to be looking for ways to put them in.  

Stereo recordings present a distorted image of  the original soundfield.   So do mono and surround recordings.  What gets us closer to being able to recreate a soundfield accurately?  It will never be perfect.  I'm OK with that, I just want to move in the direction of the most accurate recordings and reproductions.  

If I choose to impart distortion or coloration, then I want the reproduction chain to perfectly reproduce those distortions and colorations.  Otherwise, I want it invisible.  If I want distortions for euphonic effect then I will add them.  I don't want my audio cameras tinging all my audio film with purple.  If i want purple, I'll use a purple filter or a Photoshop plugin.
Title: Re: George....what's the resolution of analog?
Post by: Paul Frindle on June 05, 2004, 08:24:27 pm
Eric Vincent wrote on Sat, 05 June 2004 06:57

Quote:

posted by Paul Frindle:
Now if we look closer at the screen (and camera) quantisation we can see that if we wanted to remove the quantisation of the pixels statistically from the whole system, one method (rather than simply trying for infinite numbers of pixels) would be to shake them around at random physically whilst holding the actual image position constant wrt to the viewer. In this way all positional possibilities for the optical image would be serviced at one time or another. All quantisation would be removed from the imaging system and be replaced by amplitude noise.


Paul,

In PhotoShop, there is a filter which does this, called Unsharp Mask. It is a digital emulation of  a darkroom technique, as it happens.

It's quite simple:

On one layer, the program isolates contrasting pixels, and amplfies the contrast, to user specification.

On the second layer, it blurs those contrasting regions in a Gaussian fashion (hence "Unsharp Mask"), to user specification.

The program then overlays the two effects.

The combination of the blurred image with the sharpened image, creates the desired effect. The trick is in the proper mixing of the sharpening and the blurring, and fine tuning the two so they work together optimally.

As in audio?? ...kinda, sorta, but not really. My experiences with photography have not lent well to parallels with audio in regards to this "resolution" issue. Photography has inherent variables which exist outside the audio paradigm, and vice-versa.




No this isn't the same thing at all. This is intelligent static filtering. Far from helping the argument I seem to be getting people bogged down in misunderstandings - sorry.

What I am talking about (hypothetically) is physically moving the pixels on the screen (or camera) in a random pattern whilst holding the actual image constant wrt to the viewer, such that at some point during a given period ALL possible positions for the existence of visual information are represented statistically.

This does not increase the total accuracy of the system, but it does remove aliassing caused by discrete pixels and turns it into noise instead - without loss of detail or bandwidth associated with filtering etc..
Title: Re: George....what's the resolution of analog?
Post by: xAm on June 05, 2004, 08:27:19 pm
JDSStudios wrote on Sat, 05 June 2004 06:41

We could perhaps define audio analogue "resolution" as the difference, or lack of, between the recorded signal and the live natural audio.


I have to agree on this point with Nika... and I hate to be somewhat anal, but in a word...

ummmmmmm...

no.

Quote:

We could have a scale, with its maximum value when there would be no measurable or perceivable difference between the original live audio, and the recorded audio.


Again, no.

Resolution is resolution.

In medical imaging we use what is referred to as a resolution wedge.

It is a known thickness of lead sandwiched between two pieces of clear plastic.

The lead is laser cut into a pattern of diminishing strips of lead next to identical areas of equally diminishing void. (Essentially a section of a star pattern) (Or we used a star pattern) that is accurately measured as to the number of line pairs per inch/mm.

As radiation is passed through the resolution pattern, the overall "system resolution" is generated by measuring a difference in the total absence of radiation blocked by the lead (white) and the areas of void that let the radiation pass (black) it's the DIFFERENCE OF BLACK AND WHITE that  is MEASURABLE above the background (quantum) noise that is the resolution.

In photographic imaging, the same principal is applied in that the resolution wedge is a black and white image that is either a printed piece of paper or an electronic image representing the exact same thing.

The same holds true for offset lithography and electrostatic (xerographic) printing.

Again...  it's the DIFFERENCE OF BLACK AND WHITE that  is MEASURABLE above the background (quantum) noise that is the resolution.

What we are essentially looking at defining is the exact quantized values of the equivalence of black and white in audio.

I hope that this makes sense. What we are talking about here is a bit sticky and I hope that I'm being somewhat coherent.

Max
Title: Re: George....what's the resolution of analog?
Post by: xAm on June 05, 2004, 09:42:29 pm
josh wrote on Sat, 05 June 2004 09:10

One problem with this whole debate is that whatever we are comparing has to be measurable in some way.  So if we isolate the problem deeper into the system...  the tape head amp input to tape playback head amp output vs. the ADC input to the DAC output for example, then provided we have a controllable, repeatable and measurable way...

<snip happens>

... In order to produce a repeatable audible event for a test like this, we would have to do it with a loudspeaker, an amplifier, and then the signal generator on the front end of the amplifier.  In this scenario far and away the dominant feature of the test is the loudspeaker.


Josh, take a look at may last post please. This quickly could become a pissin' contest that it isn't. Let me see if I can clear up why I think we are about to get into an apple-n-oranges thing... and how to avoid slipping into that mode of thinking.

Quote:

So, using actual auditory information (a real sound you can hear), we cannot conduct a meaningful test regarding the resolution of a recording device.


Dude! You are so on the verge of totally getting it!!

Quote:

A recording device such as a digital recorder or an analog tape machine does not actually receive audible sound as input.  It receives a time-varying voltage as input.  The only meaningful measurement of a device like this is to measure it with respect only to the accuracy and precision of the recording and playback of the time-varying voltage.  Input a known signal (some kind of broadband, transient, etc., agreed-upon signal source), record it, then play back the ouput, and compare it to the original signal.


You had it! You had it!! You had IT!!!

Now, go back and modify the thought this way...

OK, you realize that the machine (analog OR digital) is receiving a voltage. The voltage-signal must contain the equivalent of a known quantity of a black and white image... e.g. DC/20kHz/DC/20kHz/DC/etc...

Then measure the latent information/signal at the storage device root. (tape/harddisk/ram)

To complete the circle of reproducibility, reverse the process. But the process can only be used within the realm of an electronic signal. You cannot for the sake of scientific evaluation leave that realm, unless all things are exactly the same. Otherwise yu are comparing apples to oranges.

Do you see that point?

Quote:

<snippage>...is a crude test and completely unreliable because our test equipment is the same equipment <snippage... again>...much of the most accurate audio measuring equipment we have access to is the very digital recording equipment we would like to measure.  I don't know because I have not investigated digital capture equipment for audio other than that used for recording.  If there were measuring equipment capable of determining this difference, then it means that somewhere there exists a recording and playback device that is orders of magnitude more precise and more accurate than even the high-end recording gear that we would like to test.  I don't know if this exists.


I own a simple little 100MHz scope that'll measure just about anything that is in the analog domain. The last scope I had when I was working in the digital imaging manufacturing domain was a 500MHz 16 bit buss analyzer... 20 years ago...

Check out this scope...

http://www.picotech.com/pc_oscilloscope_specification.html

Measurement is not the issue. It's what to measure that's at the heart of the debate.

Quote:

Again, though, this all is a moot point because no sane audio engineer is going to try and make a rational argument


WHOAA!!! Shoulda' stopped right there dude!  Think about that statement... sane AND audio engineer... in the same sentence!?!? And then you compound it with rational and argument!?! now THAT'S funny !<BSEG>

(Sorry, I couldn't resist... it was just too good to pass up!)

Quote:

Making an accurate, linear recording will not result in one that is lifelike to listen to!  To make a lifelike recording requires distortion.


Can you expand on this a bit? I'm serious... I must not be getting something through my thik haid or something. My ears don't artificially distort a low volume audio signal... that I know of. I do know that my brain will attempt to process and clean up a compressed sound wave that the ear naturally compresses in cases of excessive sound pressure levels... but I don't necessarily think I buy in to the statement that to capture a lifelike recording that I purposefully want or need to add ANY kind of distortion.

Max
Title: Re: George....what's the resolution of analog?
Post by: J.J. Blair on June 06, 2004, 01:35:25 am
What is the maximum resolution at which you could record the sound of my head exploding after just reading the last 14 pages of this thread?
Title: Re: George....what's the resolution of analog?
Post by: JDSStudios on June 06, 2004, 02:52:38 am
The flaw of the argument is some people wanting to nail down a singular definition for a particular word: "resolution"

Most of us know how correct Nika is on this one, because technically, the picture comparison  will never work.

That does not mean we can't understand what the person wants to know, regardless how wrong the question is.

[the old saying: understanding is superior to knowing :}

Webster's has 13 meanings for "resolution".
It started with one meaning, and probably no one at the time thought of adding 12 more.

There is no such thing as a perfect scale of anything.
That doesn't mean an imperfect scale is useless.

If we want to be difficult, there is always a way of disagreeing with just about anything!

Don't like "resolution" because of the picture pixel comparison?
Ok, then use the term "accuracy". Don't like accuracy?.. We could go on and on until you realize there is no perfect word either to communicate anything.

Still, I understand "roughly" the question, even though the choice of words is not perfect. Also, there is info missing, like for example: would you want to know what quality digital system you would use, to get a similar quality of a Studer 2" 24 Track? Probably somewhere between  24 Bit 48 KHz and 32 Bit 192 KHz, but there are so many differences between both systems, that most EEs prefer to say that the question does not make sense to begin with.

So, the answer might be just an approximation to get an idea, but far from perfect science.

Science also has art, and neither are perfect.

For the people that simply don't like the original question of this thread, do you like this statement better:

"An electron, once not observed, can be in two places at the same time" - [This is the principle IBM is using in their latest single and double electron Quantum computers, that can resolve a period of a function in a couple of cycles, as compared to many more cycles needed in the typical house hold computers we now use]
Title: Re: George....what's the resolution of analog?
Post by: JDSStudios on June 06, 2004, 03:24:59 am
Theory is when you know something, but it doesn't work.
Practice is when something works, but you don't know why.
Engineers combine theory and practice:
Their questions and answers do not work and they don't know why.



Title: Re: George....what's the resolution of analog?
Post by: jazzius on June 06, 2004, 11:37:47 am
FWIW, i knew it was a silly question to start off with.....but i figured by making it a bit wooly, it would get some interesting responses.
Title: Re: George....what's the resolution of analog?
Post by: ted nightshade on June 06, 2004, 01:52:24 pm
Most audio playback of real events that got recorded is distorted in the following way: it's just not loud enough on playback. Usually the real instruments are a great deal more acoustically powerful than the playback system can go clean and healthy.

So, unless we stick to lifelike playback levels, we are getting into tricking the listener to make the playback seem lifelike. This is where you start to need to distort things in a different way to make up for the distortion of not playing it back at real-life levels.

So, harmonic generation, compression, EQ etc.
Title: Re: George....what's the resolution of analog?
Post by: Paul Frindle on June 06, 2004, 08:54:07 pm
JDSStudios wrote on Sun, 06 June 2004 07:52

The flaw of the argument is some people wanting to nail down a singular definition for a particular word: "resolution"


Don't like "resolution" because of the picture pixel comparison?
Ok, then use the term "accuracy". Don't like accuracy?.. We could go on and on until you realize there is no perfect word either to communicate anything.




This is obviously not so since a Noun can entirely define a singular object completely - even an unique one.

Ok - well try the old word 'fidelity'. It works because it has meaning which refers to the 'measure of faithfulness' to the original stimulus. Vague though this term is - it does convey the (arguably noble) INTENTION of the effort (i.e. to attempt to improve reproduction of sound) and crucially does not seek to pontificate/question the technology used therein Smile

If we are trying to replace an old term like fidelity with a new exciting one - at the very least we ought to apply the correct laws of language? But of course it would be dangerous if specific claims attached to the new term were found to be incorrect or scientifically indefensible.

And therein rests the point I made earlier: Whilst it is easy and expedient to increase the bit depth of the data and/or the sample rate and call it 'high resolution' and let the user interpret what he will from that - it is far more difficult (if not practically impossible currently) to claim that there are defensible reasons why these changes in themselves should improve the sound of the programme. The reasons being that AFAIK there is still no (actual) evidence that we are particularly sensitive to signals beyond 20KHz or so - and there is no evidence that dynamic ranges beyond 90 - 100dB or so can make a significant difference to the listener within any practical playback environment.

Thats why we are arguing - because (emotionally and morally) we are expecting there to be some defensible science to accompany the assumed message the term 'resolution' has implanted into the discussion at the behest of marketers - but sadly we find that there apparently isn't any - yet Sad We have not yet accepted that at worst its possible that its use is cynical - or at best the technology has been applied precipitously, for reasons which might not ultimately be in our (the user's) best interests.

The most crucial point of all being; that the assumption that this new term 'resolution' would naturally lead to better sound - is entirely OURS - so practically (and possibly legally) its beyond challenge!
Title: Re: George....what's the resolution of analog?
Post by: Nika Aldrich on June 06, 2004, 09:02:52 pm
JDSStudios wrote on Sun, 06 June 2004 08:24

Theory is when you know something, but it doesn't work.
Practice is when something works, but you don't know why.
Engineers combine theory and practice:
Their questions and answers do not work and they don't know why.






The difference between theory and practice is that in theory they are the same.

Nika.
Title: Re: George....what's the resolution of analog?
Post by: Curve Dominant on June 06, 2004, 10:29:50 pm
Quote:

The difference between theory and practice is that in theory they are the same.

Nika.



It took me a minute to realize why that makes sense.
Title: Re: George....what's the resolution of analog?
Post by: josh on June 07, 2004, 04:00:16 pm
xaMdaM wrote on Sun, 06 June 2004 02:42



Josh, take a look at may last post please. This quickly could become a pissin' contest that it isn't. Let me see if I can clear up why I think we are about to get into an apple-n-oranges thing... and how to avoid slipping into that mode of thinking.


I have skipped the articles dealing with the analogy of audio to digital imaging...  just not enough hours in the day and it didn't seem relevant...  can you point me to the exact post?

Quote:


You had it! You had it!! You had IT!!!

Now, go back and modify the thought this way...

OK, you realize that the machine (analog OR digital) is receiving a voltage. The voltage-signal must contain the equivalent of a known quantity of a black and white image... e.g. DC/20kHz/DC/20kHz/DC/etc...

Then measure the latent information/signal at the storage device root. (tape/harddisk/ram)

To complete the circle of reproducibility, reverse the process. But the process can only be used within the realm of an electronic signal. You cannot for the sake of scientific evaluation leave that realm, unless all things are exactly the same. Otherwise yu are comparing apples to oranges.

Do you see that point?


I don't really understand why you are pointing this out.  Isn't this what I had described to begin with (approximately)?  yes, I was making the point that you cannot compare a recording to an actual auditory event and blame the recording aparatus for a difference when it's far from being the weakest link in the chain.  Maybe your point is that if in fact you could play it back through the mic pre and microphone it would be a usable test?  I don't know if that was what you were trying to say or not.  But if it were, well that wouldn't work either, since the microphone is the bottleneck to begin with, and having to ram information through it twice would just compound the distortion.

Quote:



Quote:

<snippage>...is a crude test and completely unreliable because our test equipment is the same equipment <snippage... again>...much of the most accurate audio measuring equipment we have access to is the very digital recording equipment we would like to measure.  I don't know because I have not investigated digital capture equipment for audio other than that used for recording.  If there were measuring equipment capable of determining this difference, then it means that somewhere there exists a recording and playback device that is orders of magnitude more precise and more accurate than even the high-end recording gear that we would like to test.  I don't know if this exists.


I own a simple little 100MHz scope that'll measure just about anything that is in the analog domain. The last scope I had when I was working in the digital imaging manufacturing domain was a 500MHz 16 bit buss analyzer... 20 years ago...

Check out this scope...

http://www.picotech.com/pc_oscilloscope_specification.html

Measurement is not the issue. It's what to measure that's at the heart of the debate.



I didn't check out that scope.  But I will point out that a scope with 500MHz bandwidth is not necessarily linear under 20kHz.  A scope with 500MHz bandwidth does not normally get employed to measure 20kHz phenomenon with accuracy.  Even the probe and preamplifier for the probe are not up to the task...

bunny trail...

During the early development of ADSL (aka "DSL") modems we used an industry-standard network/spectrum analyzer (very expensive piece of equipment) to measure the performance of the analog front end filters and line driver of the modems we were developing.  The differential active probe that was supplied lacked bandwidth under 1MHz to be able to accurately measure upstream performance or voice-band (under 30kHz for DSL purposes) noise response.  This was a $2K probe.  We had to design and build a special probe (which was basically a preamplifier with alligator clips for input) that would properly measure in this band.

Or think about it this way...  a capacitor has a particular frequency at which it is resonant...  at other frequencies, it introduces excessive distortion.  A capacitor is typically the first device in series with the input to the preamplifier on an oscilloscope.  Now, we all know from working with audio stuff that even with the same value and type of capacitor (mylar film, polystyrene, etc.), different capacitors can sound audibly very different and are measurably very different...  imagine if we chose one for the input without much regard for whether it worked properly at 3 kHz but instead focused on the performance at 33MHz?

Because consider who buys a 500MHz oscilloscope...  an audio engineer?  Nope.  You use that on high-speed circuits, that's where it works best, and it probably does not work nearly as well at 20-20kHz as a high-end audio converter.

Quote:


Quote:

Making an accurate, linear recording will not result in one that is lifelike to listen to!  To make a lifelike recording requires distortion.


Can you expand on this a bit? I'm serious... I must not be getting something through my thik haid or something. My ears don't artificially distort a low volume audio signal... that I know of. I do know that my brain will attempt to process and clean up a compressed sound wave that the ear naturally compresses in cases of excessive sound pressure levels... but I don't necessarily think I buy in to the statement that to capture a lifelike recording that I purposefully want or need to add ANY kind of distortion.

Max


I wrote about this oh on about page 9 of this thread...  When aided by your other senses, your brain is able to provide selective filtering and sensory effects to sound input...  kind of like how in a noisy environment you can carry on a conversation with someone but if you made a recording of it you would not be able to hear it.  You can "focus" on sounds, filter others...  When you walk into a room, for example, your brain can quickly begin to filter out the reverberation of the room so you don't notice it.  There are all kinds of psychoacoustic effects that should be taken into account when considering what's important about audio recording and reproduction.  
Title: Re: George....what's the resolution of analog?
Post by: Nika Aldrich on June 07, 2004, 05:38:44 pm
josh wrote on Mon, 07 June 2004 21:00

I wrote about this oh on about page 9 of this thread...  When aided by your other senses, your brain is able to provide selective filtering and sensory effects to sound input...  kind of like how in a noisy environment you can carry on a conversation with someone but if you made a recording of it you would not be able to hear it.  You can "focus" on sounds, filter others...  When you walk into a room, for example, your brain can quickly begin to filter out the reverberation of the room so you don't notice it.  There are all kinds of psychoacoustic effects that should be taken into account when considering what's important about audio recording and reproduction.  



Josh - good points.

At a pure ear level two signals can be neurologically identical, meaning that the exact same neurons fire at exactly the same pace, yet we can perceive that they "sound" different if they happened in different environments.  The ears, in combination with the rest of our senses (like "looking" at the orchestra on stage, for example) put together an entire sensory picture of what is happening.  By removing some of that exta sensory stuff and only leaving the audible sense we humans can have the perception that something is audibly different when in fact it is not.  This has nothing to do with theories that we "hear" in other ways, nor that we "perceive" information above our audible range.  It has to do exclusively with the entagling of the audible sense with legitimate other sensory stuff (like the eyes) and giving the impression of how something sounds audibly which is different from how it is.

In order to compensate for this, a recording that is supposed to give the same mental impression as a, say, live performance may have to add some intentional distortion so that the brain is fooled into developing a mental picture of the performance that is identical to the version that had information from the other senses.  

An interesting experiment:  Take a recording of something and play it in a room.  Then play the same thing with a video playing on a TV screen in the room.  Ask the blind audience which sounds "better."  Undoubtedly it will be the version playing when they can see the video.  In order to make the version that does not have the video "sound" the same to the testers you will have to somehow distort it, even though it is neurologically identical.

Again, I am trying to answer the question about why it would be necessary to intentionally distort something in order for it to sound un-distorted.

Nika.
Title: Re: George....what's the resolution of analog?
Post by: xAm on June 07, 2004, 10:52:22 pm
josh wrote on Mon, 07 June 2004 16:00

I have skipped the articles dealing with the analogy of audio to digital imaging...  just not enough hours in the day and it didn't seem relevant...  can you point me to the exact post?


#7161

Quote:

Maybe your point is that if in fact you could play it back through the mic pre and microphone it would be a usable test?  I don't know if that was what you were trying to say or not.  But if it were, well that wouldn't work either, since the microphone is the bottleneck to begin with, and having to ram information through it twice would just compound the distortion.


My bad...

I kept reading into it that you were attempting to say that it was ok to compare a measuremnt sequence where the analog path was supposed to be going through a weak linked playback where the digital path didn't have to... which is kinda' insane... like... comparing apple-n-oranges.

I still say that measurement is not the issue. It's what to measure that's at the heart of the debate.

Quote:

bunny trail...


Yes it is, isn't it?!? That's partly why I was goin' goofy over the apples to oranges comparison I thought you were making.

Quote:

During the early development of ADSL...


Yeah, the bunny comes back out of the hole to play with skin effect and tuned circuits and runs back down... got it and agree.

Quote:

Can you expand on this a bit?


Quote:

I wrote about this oh on about page 9 of this thread...  When aided by your other senses, your brain is able to provide selective filtering and sensory effects to sound input...  kind of like how in a noisy environment you can carry on a conversation with someone but if you made a recording of it you would not be able to hear it.  You can "focus" on sounds, filter others...  When you walk into a room, for example, your brain can quickly begin to filter out the reverberation of the room so you don't notice it.  There are all kinds of psychoacoustic effects that should be taken into account when considering what's important about audio recording and reproduction.  



OK... No problem here either. Again, in thinkin' about all this over and over and over... the swimmies set in and sometimes very sound rational thinking all of a sudden doesn't even "sound" like words... (I thinks its that noise above background level issue again... with all both of my synapses firing at the same time it gets pretty loud in here!)

Actually I think I was arguing your point against myself for lack of thorough reading. DOH! Call me stupid, close the box, seal it up tight and send to c/o general delivery, postage due.
Title: Re: George....what's the resolution of analog?
Post by: xAm on June 07, 2004, 11:01:29 pm
Nika Aldrich wrote on Mon, 07 June 2004 17:38

Again, I am trying to answer the question about why it would be necessary to intentionally distort something in order for it to sound un-distorted.

Nika.


Nika,

I got jaded by a previous post and put on the headset that was not thinking about all forms of distrortion... or distortion in the neurological sense, but distortion in the fuzzbox sense.

TOO many hours in frot of the CRT... I need to get AWAY from these things... I think 15750 combines with the harmonics from 10000 rpm platters, and is frying my brain!

Max
Title: Re: George....what's the resolution of analog?
Post by: malice on June 11, 2004, 03:07:25 pm
I can't believe this


You are all still debating over the resolution of analog ?

amazing  Confused  Laughing

best

malice
Title: Re: George....what's the resolution of analog?
Post by: amorris on June 22, 2004, 12:17:42 pm
I think you have asked more than one question with your post and I think they are not so related. what is the resolution? i think that the resolution comes in when your turn a knob, not the sample depth. whenever I have worked on anything digital, the resolution of the trim pots  is limiting because even though i can get a good sound on any particular source, when 48-98 tracks come into play, i cant scoshe-it a little to dial it in like I can on a neve or SSL etc. I feel that all of my adjustments are off by 0.01%. now that doesnt sound like alot until 60 tracks with eq and compress on all, with all of them not where i could get them. I bet you can hear 2% distortion(imperfection). I beleive that is why no one mixes the big records on Protools, they still go to the big rooms not for the summing buss, but the ability to scoshe-it on any particular setting, and the resolution of the mix, not the sample. my opinion only, but i have seen a lot of these big records being done, songs you hear everyday.
Title: Re: George....what's the resolution of analog?
Post by: lucey on June 24, 2004, 11:31:41 am
Why does 'analog sound better to some people in some cases' is one question.

What's the resolution of analog' is another.  I think it's a silly question, however, as it's worded and thought of from a digital perspective.




Analog sounds better in some cases to some people due to the analogous nature of the media, the intial vibration never leaves the reality plane.  It's always a vibration.   So yes, sound is distorted, yet it has it's original integrity in terms of it's quality.  It's got the vibe, literally.

Digital maintains linearity to varying smaller degrees with better technology, yet changes the fundamental quality of the sound from a vibe to a number.  This simple fact is the whole biscuit.

It's as basic as asking yourself this ... if you were a kid which waterslide would you rather ride?

a) the smoothe and wet one with some friction and a few slight turns, or

b) the one with tiny stair steps and perfectly even friction, straight down?



Scientific minds are of great help to many aspects of music, but the scientific ear does not hear the subtleties of the stair steps as the catastophic loss of integrity that musicians hear.

Simultaneously musicians do not hear the catastophic loss to linearity as a problem, even as scientists work to fix it in every step 'forward'.
Title: Re: George....what's the resolution of analog?
Post by: Nika Aldrich on June 24, 2004, 11:40:38 am
lucey wrote on Thu, 24 June 2004 16:31

It's as basic as asking yourself this ... if you were a kid which waterslide would you rather ride?

a) the smoothe and wet one with some friction and a few slight turns, or

b) the one with tiny stair steps and perfectly even friction, straight down?



Scientific minds are of great help to many aspects of music, but the scientific ear does not hear the subtleties of the stair steps as the catastophic loss of integrity that musicians hear.


Why are you ignoring the role of the reconstruction filter at the end of the D/A converter?

Digital does NOT have all of the stair-steps that you describe.  Digital is only a representation of the waveform - NOT the waveform itself.  The original waveform still has to be reconstructed from the sample points.  Simply doing a "dot to dot" or sample-hold reconstruction is clearly inadequate, as neither of those re-create the original waveform.  When proper reconstruction filtering is done there is no  "stair-stepping," and continuing to refer to such obfuscates the way in which digital actually works and confuses the questions.

Nika.
Title: Re: George....what's the resolution of analog?
Post by: Chuck on June 24, 2004, 12:31:30 pm
lucey

 

Digital maintains linearity to varying smaller degrees with better technology, yet changes the fundamental quality of the sound from a vibe to a number.  This simple fact is the whole biscuit.

It's as basic as asking yourself this ... if you were a kid which waterslide would you rather ride?

a) the smoothe and wet one with some friction and a few slight turns, or

b) the one with tiny stair steps and perfectly even friction, straight down?



Hi Brian,,

I think you are - by intuition - mentioning one of the most important distortion mechanisms in digital audio.

During playback we have to generate a analog signal out of squares. Even if the DAC chip has some inbuildt analog filter, it was squares in the beginning.

And squares consist of 3rd order harmonics only and the faster the settling time of your DAC the sharper the edge, and the higher the harmonics go.

So a lot of the art of making digital sound good, lies in smoothing the squares. Oversampling reduces the stepsize (at least with R2R converters), but does not reduce the sharpness of the square's edges.

I have made good sounding result with a RLC filters and transformers. The inductivity presents an inertia for fast signals.

Charles Smile
Title: Re: George....what's the resolution of analog?
Post by: Level on June 24, 2004, 01:53:42 pm
All inductors are wave shaping devices, including the voice coils of your loudspeakers. The key is to have the signal throught the chain represent music and emotion. Whatever it takes to get there is fine by me as long as the emotion translates universally. May audiophiles "love" tubes due to the fact that the output transformers (iron/nickle/cobalt etc) reshape the signal to distortions that are more pleasing to them.
Title: Re: George....what's the resolution of analog?
Post by: RobertRandolph on June 24, 2004, 03:57:46 pm
What the heck is all this talk about squares!?!

I really dont see where a lot of you are getting information from... IF you plot a sine wave on a peice of paper, given 2 points... are you plotting squares?! NO. Because you have a mathmatic formula telling you it is a sine or cosine. Likewise, with digital audio conversions, we know it will be a sine. So the converter does not just "draw squares".

Likewise, if it is a square wav, saw, triangle etc.. You must remember this is  combonation of sine waves with various harmonics at specific amplitudes and intervals. Still sines.
Title: Re: George....what's the resolution of analog?
Post by: lucey on June 24, 2004, 11:22:27 pm
Chuck wrote on Thu, 24 June 2004 11:31



Hi Brian,,

I think you are - by intuition - mentioning one of the most important distortion mechanisms in digital audio.

During playback we have to generate a analog signal out of squares. Even if the DAC chip has some inbuildt analog filter, it was squares in the beginning.

And squares consist of 3rd order harmonics only and the faster the settling time of your DAC the sharper the edge, and the higher the harmonics go.



Wow, a tech who is not afraid to say the word "intuition"

Cool looking product on your site Chuck, the Tube-u-lator laquer ... interesting indeed.

(You should change your signature line so we can easily link your website)

RobertRandolph wrote on Thu, 24 June 2004 14:57

What the heck is all this talk about squares!?!

I really dont see where a lot of you are getting information from... IF you plot a sine wave on a peice of paper, given 2 points... are you plotting squares?! NO. Because you have a mathmatic formula telling you it is a sine or cosine. Likewise, with digital audio conversions, we know it will be a sine. So the converter does not just "draw squares".



Doesn't a converter draw sines of a slope that is a guess?  And if so are they perfect reproductions of the original curve?

How can they be when an A to D measures in samples and a D to A tries to remember the curve?

And just for fun, what if a "perfect" and distortion free reproduction is not the most musical?  what would you do then?

(Maybe the ATR 2" 8 track is the most musical recorder ever made as it has lower distortion and noise floor yet the ear-like non-linearities of all tape recording?

Although my Pacific Microsonics Model One is pretty sweet on the 2ch. A to D and D to A )


Quote:


Likewise, if it is a square wav, saw, triangle etc.. You must remember this is  combonation of sine waves with various harmonics at specific amplitudes and intervals. Still sines.


Then what are those 3rd harmonics all about?  When will they go away?

And where is the full impulse energy of the wave as it was played in the air?  It does go away with digital ... any digital.  It is distorted by present with analog, any analog.
Title: Re: George....what's the resolution of analog?
Post by: steve parker on June 25, 2004, 08:50:23 am
 quotes all Brian:

 "Doesn't a converter draw sines of a slope that is a guess?"

no - a perfect reconstruction of the original

  "And if so are they perfect reproductions of the original curve?"

yes

  "How can they be when an A to D measures in samples and a D to A tries to
   remember the curve?"

DA doesn't "remember" anything.
the "snapshot" idea is wrong - an AD gets the information needed to completely accurately reconstruct the wave - subject only to the condition that the highest frequency you're sampling must be slightly less than half the sampling rate.
increasing the sampling "snapshots" ONLY allows you to capture higher frequencies.
it doesn't allow you to better capture the ones capturable by lower rates.

   "And just for fun, what if a "perfect" and distortion free reproduction is not
    the most musical?  what would you do then?

give up!
seriously, if you want less than perfect distorted music that is a creative choice.
BUT, less than perfect distorted REPRODUCTION is a contradiction in terms.






   "Likewise, if it is a square wav, saw, triangle etc.. You must remember this is
   combonation of sine waves with various harmonics at specific amplitudes
   and intervals. Still sines.
    Then what are those 3rd harmonics all about?  When will they go away?"

the "third harmonics" is one backwards extrapolation too far - from sample-hold to actually understanding the information as a stair-step picture to square waves. this is just the wrong way to think about the information - more "snapshotiness"

   "And where is the full impulse energy of the wave as it was played in the air?
     It does go away with digital ... any digital.  It is distorted by present with
      analog, any analog. "

can you explain exactly what you mean?
this sounds like you are suggesting that digital doesn't capture inital peaks as well as any analog?

all the best!

steve parker.
Title: Re: George....what's the resolution of analog?
Post by: Nika Aldrich on June 25, 2004, 10:26:35 am
lucey wrote on Fri, 25 June 2004 04:22


Doesn't a converter draw sines of a slope that is a guess?  


No, and THAT is the beauty of Nyquist.  Just like we can reconstruct a circle by only capturing 3 points in it, and just like we can reconstruct a line with only two points, we can reconstruct a complex waveform with a certain frequency of sampling, so long as it contains no content above N.  And the amazing thing is that it actually works.  So what the D/A converters do is not a "guess" but rather a very specific process that reconstructs the original waveform from the samples.  There is absolutely no guessing about it.

Even if two sample points happen to be very near the zero crossing but the waveform they represent is at full scale, the original waveform can be extracted based on the previous and following sample points.  There is only one waveform that can fit onto those sample points and is properly band limited.  The task of the converter is to find it.

Quote:

How can they be when an A to D measures in samples and a D to A tries to remember the curve?


I hope we answered this (thanks, Steve).  If I draw a circle on a piece of paper and then sample it at three points and then give you two things:  A.  the knowledge that it is a circle, and B. the three sample points - you can reconstruct the circle.  You aren't "remembering" anything.  

Quote:

And just for fun, what if a "perfect" and distortion free reproduction is not the most musical?  what would you do then?


Probably add some digital processes prior to reconstruction that make it distorted in the most desirable way.

Quote:

Then what are those 3rd harmonics all about?  When will they go away?


Those third harmonics all begin above the Nyquist frequency, so if you filter out everything above Nyquist all of the 3rd harmonics go away and you're left with the original waveform.

Quote:

And where is the full impulse energy of the wave as it was played in the air?  It does go away with digital ... any digital.


What goes away in digital is only the frequency content in the impulse that the human ear can't hear, anyway.  An impulse contains all frequencies, much like white noise.  Our ear filters that and only allows us to hear the frequency content in the impulse that is below around 20kHz.  The waveform that the ear "hears" is nothing like an impulse.  It looks like the impulse response of an IIR filter.  

The task of digital is to present to the ear what the ear hears, so while ALL of the energy of the wave is indeed not captured by digital, since digital filters like the ear does, the entirety of that wave that the ear hears is indeed captured and not distorted.

Nika.
Title: Re: George....what's the resolution of analog?
Post by: lucey on June 25, 2004, 04:50:29 pm
Nika Aldrich wrote on Fri, 25 June 2004 09:26


The task of digital is to present to the ear what the ear hears, so while ALL of the energy of the wave is indeed not captured by digital, since digital filters like the ear does, the entirety of that wave that the ear hears is indeed captured and not distorted.

Nika.



So from this perspective which 2 channel converter sounds the most accurate

and which one the most musical, if any different

to you?

Title: Re: George....what's the resolution of analog?
Post by: djui5 on June 25, 2004, 05:36:06 pm
Nika Aldrich wrote on Fri, 25 June 2004 08:26



The task of digital is to present to the ear what the ear hears, so while ALL of the energy of the wave is indeed not captured by digital, since digital filters like the ear does, the entirety of that wave that the ear hears is indeed captured and not distorted.

Nika.



Nike,

I would say that I disagree......the digital community might want to accomplish this in the end..but is not currently doing so.


Where did you get this from anyways?....digital filters like the ear does?
Title: Re: George....what's the resolution of analog?
Post by: Nika Aldrich on June 25, 2004, 06:27:08 pm
djui5 wrote on Fri, 25 June 2004 22:36

Where did you get this from anyways?....digital filters like the ear does?


I'm not sure exactly the nature of your question - there are lots of ways to take it, I suppose.

The ear is a filter just like any other natural device.  There are several factors at work in the ear that cause it to be a filter - The eardrum itself is a transducer with a specific frequency response just like any microphone.  The ossicles are mechanical devices that filter more like the speaker magnet/coil combination.  The oval windowfilters again like a transducer - a microphone or speaker.  Inside the cochlea we have the basilar membrane - essentially a taught piece of material stretched across the basilar membrane.  When liquid flows over it is causes it to resonate.  As with any transducer, however, it has a fixed and specific frequency response.  The fascinating thing about the basilar membrane is that it is long and shaped such that certain frequencies resonate better at different places.  Higher frequencies resonate the basilar membrane closer to the entrance to the cochlea, where the width of the membrane is very small - less than a millimeter.  Lower frequencies resonate better at the opposite end (the helicotrema) where the basilar membrane is wider - around 1.7mm.  This means that each spot on the basilar membrane is actually a filter unto itself, allowing the membrane to only resonate at particular frequencies.  As a whole, however, the basilar membrane is, unto itself, a filter, in that it simply can't resonate at frequencies higher than the mechanical structure, elasticity, and its tautness allows, nor lower than its loosest point allows.  Finally, there is the individual filtering of individual hair cells and their respective neurons.  Each hair cell can only respond to specific frequencies.  The lowest ones can respond to around 10Hz.  The highest ones respond to around 1kHz.  The combination of various of those firing asynchronously provides all audibility between 1kHz and around 4kHz.  Anything above that we only hear based on the physical location on the basilar membrane that causes the hair cell neurons to fire.  Finally, there is the filtering caused by the impedence caused by the round window as the waves of fluid pressure in the inner ear meet the middle ear again.

The combination of all of these filters causes our ears to function as one big filter with several individual components.  This filtering in the ear causes us to have an upper limit at typically a little less than 20kHz, and changing with age and as inner hair cells disintegrate.  The complete shape of the filtering of the ear is not as simple as a few-order IIR filter, but it is safe to say it is a near-minimum phase IIR filter with a .25-.4ms window or so.  The bottom line is that the waveform that reaches the auditory canal is heavily filtered by the time it reaches the VIIIth auditory nerve, and any frequency content outside of certain boundaries is attenuated entirely.  There are other things that are filtered out as well as a result of the masking, etc.  We can understand the difference between what goes into the ear and what gets to the brain by mocking up a simple filter that rolls of at 20kHz and look at what happens when we pass various signals into it - such as an impulse, a sine wave at 25kHz, a square wave at 5kHz, etc.  We notice that what the brain gets with which to decipher the waveform is nothing at all like what enters the auditory canal.

Digital systems also have to filter the audio - in this case to remove frequency content that would allow aliasing.  The filtering used in these digital systems is specifically designed to exceed the boundaries of the human ear, such that any waveform that enters a digital system and then enters the ear would not sound any different than if that waveform were to just enter the ear.  

When I say that digital systems filter audio "like the ear" I do not mean that we use minimum phase IIR filters with the same window, et al, but I do mean that digital systems filter out all material above 20kHz, just like the ear does before it gets sent to the brain.  In fact it is good that the filters in the digital systems are not exactly "like the ear" as the non-linearities in the ear, if compounded by more than one instantiation, would cause audible distortion.  The filters used in digital, therefore, allow no phase-shift so that the only phase-shifting is that which is done by the ear itself, for example.  So long as the filters in the digital systems exceed the boundaries of the ear the audio is capable of being accurately presented to the ear as though the digital systems were not in the circuit.

Of course many methods of cutting corners on these filters have been implemented over the years, including allowing slight amounts of aliasing in, phase shifting the audio at various frequencies, and rolling off some of the viable audible range.  The fact that this has been done in no way insinuates that it has to be, however.

One last point - we have already accepted, have we not (?), that any digital system inherently functions as a filter in that it has strict boundaries, and anything outside of those boundaries is incapable of being transmitted.  The ear is a digital device.  As such, it is a filter and has strict boundaries very much akin to the digital systems designed for its benefit.

I hope this answers your question?

Nika.
Title: Re: George....what's the resolution of analog?
Post by: RobertRandolph on June 25, 2004, 07:54:08 pm
lucey wrote on Fri, 25 June 2004 21:50

Nika Aldrich wrote on Fri, 25 June 2004 09:26


The task of digital is to present to the ear what the ear hears, so while ALL of the energy of the wave is indeed not captured by digital, since digital filters like the ear does, the entirety of that wave that the ear hears is indeed captured and not distorted.

Nika.



So from this perspective which 2 channel converter sounds the most accurate

and which one the most musical, if any different

to you?




I think this shows Nika's ideas much more forward thinking than you see...

This question and idea behind it perfectly show why different ears accept different devices to be the epitomy of perfect. As long as we have different ears there will be different devices that best represent what we hear naturally.

Although Im not sure if Nika realizes the beauty of his statement...
Title: Re: George....what's the resolution of analog?
Post by: djui5 on June 25, 2004, 11:15:45 pm
I see...thanks Nika
Title: Re: George....what's the resolution of analog?
Post by: lucey on June 30, 2004, 01:04:37 am
fuze wrote on Fri, 25 June 2004 07:50



can you explain exactly what you mean?
this sounds like you are suggesting that digital doesn't capture inital peaks as well as any analog?

all the best!

steve parker.



Steve, I admit to a limited understanding of the subtle technicalities of digital recording.  I do know tone however, and specifically I know vibrations.

To my ear any AD DA (even my amazing Pacific Microsonics) is fundamentally altering the waveform's quality.  It becomes something other than analogous to the original sound ... wholly different.

This is a qualitative change, and perhaps something that is not easy to measure or specifically quantify.




So with analog, I hear the original snare transients or guitar picks, or general harmonics, only distorted.

With digital I hear a facsimilie of the original, yet in a more perfectly preserved or perfect state ... of simulation.
Title: Re: George....what's the resolution of analog?
Post by: Nika Aldrich on June 30, 2004, 10:37:41 am
lucey wrote on Wed, 30 June 2004 06:04



Steve, I admit to a limited understanding of the subtle technicalities of digital recording.  I do know tone however, and specifically I know vibrations.


I am not surprised that you hear differences between analog and digital systems.  I've heard your music and work you've mixed, and my personal observation is that you tend toward very rich sounding analog material and equipment.

Quote:

To my ear any AD DA (even my amazing Pacific Microsonics) is fundamentally altering the waveform's quality.


Perhaps the PMi DOES alter the waveform's quality.  How have you tested it and what other converters have you tested - and how?

Nika
Title: Re: George....what's the resolution of analog?
Post by: steve parker on June 30, 2004, 12:53:27 pm
"To my ear any AD DA (even my amazing Pacific Microsonics) is fundamentally altering the waveform's quality.  It becomes something other than analogous to the original sound ... wholly different.

This is a qualitative change, and perhaps something that is not easy to measure or specifically quantify."

hi.

this is exactly (usually) my experience too.
my only questions are, "are you sure that every other link in the chain *is* capable of reproduction without alteration?"

and "can you therefore be sure that the ad/da is what is causing this less-than-perfectness?"

steve.





Title: Re: George....what's the resolution of analog?
Post by: danlavry on June 30, 2004, 03:22:35 pm
I find this thread very amusing. It is a good example for how comments on a subject drift into and out of focus. When I saw the question about “resolution of analog” my first knee jerk reaction was – resolution is not a terminology for analog. It is terminology for digital. Of course I am viewing things from engineering science and math standpoint. I now see that an ear person may use such term for what the ear can resolve, and indeed it is a valid way to look at it.

Indeed, the way I would approach the question is from an EE standpoint, and I would start with “what is the resolution of digital”. An EE would immediately focus on the number of bits, which sets the dynamic range (noise floor) with about 6dB per bit (thus 16 bits is 6*16 = 96dB, 20 bits is 20*6 = 120dB dynamic range). Clearly, this is a starting point that assumes that all the bits are acting as desired (good bits). The reality is that non of the 24 bits AD and DA can yield 6*24=144dB dynamic range. One may view the lower bits are “fuzzy”, mis behaving, at best randomly bouncing up and down, at times also moving about with some influence from the signal itself… As far as I am concerned, a bit that “moves around a lot” relative to it’s weight is not following the music, thus is useless, and is a “marketing bit” 

There is always some constant noise out there with the signal, be it an analog system or digital one. The lower bits in an attempted design of say 24 bit AD or DA are “overwhelmed” by the analog noise, reducing the dynamic range to less than 24 bits. On the other hand, a real 20 bits performer (converter) contains so little noise relative to say a 16 bit system, that the noise figure – thus the dynamic range of the digital system may be dictated by 6*16 = 96dB without any limitations due to the analog.

So in a sense, I would tie the answer to the question regarding the resolution of analog to what it would take to accommodate some specified digital criteria. What is the resolution of analog? It is tied to “what is the dynamic range of analog” or “what is the noise of analog”. The answer always depends on the specific gear.  Figuring the noise is just engineering stuff. The noise is there because electronic parts generate noise, and because unwanted signals couple into the signal path. Even a simple resistors, just a piece of say carbon, has electrons bouncing inside randomly and generating noise. Of course, with low resistance (such as metal wire or good conductor), such electron motion (current) can not build much voltage. But with high resistance you get surprising amount of noise, certainly plenty enough to make 24 real bits a non real proposition in this day and age… And of course, semiconductors is a whole other level of complexity… and so no…

So this kind of analog noise is what limits dynamic range. Some of that noise appears with the signal. Some of this noise limits the dynamic performance of what the gear is capable of, be it analog or digital.

A lot of what I said is a bit simplistic. I can not cover everything in a massage. But this is basically an engineering approach (EE type, not a recording and mastering type).

Every real digital bit provides real value in terms of dynamic range as well as lower distortion (certainly in terms of low level signals by themselves or riding on a high level signal) is a good thing. Lower noise is also good thing, and in that sense, and even “meets” the “ear type definition of resolution” – hearing small signals by themselves or when other music is played. I can appreciate the ear type people that that wish to include frequency issues with the word resolution. After all, resolution is an everyday word, not just to be used by audio converter designers. For example, video guys have their own meaning attached to it.

But I am sorry to see so many people misled by the notion of increased sample rate as contributing anything to resolution. The marketing guys, and some ear types with less technical savvy seem to equate high resolution audio with increased bits and sample rate. The fact is – it is about bits, not about sample rate. More real bit increase dynamic range. Faster sampling beyond a certain point does nothing. But that is all covered in the 192KHz thread…    


BR
Dan Lavry
Lavry Engineering
Title: Re: George....what's the resolution of analog?
Post by: Johnny B on July 01, 2004, 03:02:29 am
Dan,

Are you saying that real improvements could be made by going to 32-bit converter chips?  

Sure some of those 32 bits could be wasted, but those extra bits could come in handy, at some point down the road, ya never know... LOL.

Title: Re: George....what's the resolution of analog?
Post by: Level on July 01, 2004, 03:38:24 am
I like dynamic range and more intervals between dynamics=more fluid, analoguish. We have the computing power, lets use it!

If you don't like it, decide on what you DO like with your overall sensations of what is 'best' for you and your client.
Title: Re: George....what's the resolution of analog?
Post by: steve parker on July 01, 2004, 08:48:38 am
"more intervals between dynamics=more fluid, analoguish"

but there aren't more intervals between dynamics im any meaningful sense.
extra bits just make the rounding error half of the next bit back leading to this rounding errors noise being lower.

steve parker.
Title: Re: George....what's the resolution of analog?
Post by: Nika Aldrich on July 01, 2004, 10:29:10 am
Johnny B wrote on Thu, 01 July 2004 08:02

Dan,

Are you saying that real improvements could be made by going to 32-bit converter chips?  


Believe me, he's not saying that.

Nika.
Title: Re: George....what's the resolution of analog?
Post by: danlavry on July 01, 2004, 02:28:22 pm
Johnny B wrote on Thu, 01 July 2004 08:02

Dan,
Are you saying that real improvements could be made by going to 32-bit converter chips?  
Sure some of those 32 bits could be wasted, but those extra bits could come in handy, at some point down the road, ya never know... LOL.




One must keep in mind that there are 2 separate issues here at play:
1. The number of bit you can get out of a real wold AD or DA, which has a lot to do with analog noise. Lets face it, we do not have real 24 bits performance gear, nor do we have 22 bits. Face it - the best mic pre with a shorted input makes enough noise to "walk all over" a real 24 bit AD performance (if you could have one). 24 bits would require 144dB signal to noise ratio, at the microphone. You just can not have it yet.

2. The number of bits used for digital signal processing (DSP). This is another issue all together.

Of course the initial reaction is: why 32 bits DSP if the signal is already below 24 bits? Why will we not have the analog noise "walk all over" the very low quantization noise of the DSP?

Of course, if all you wanted is say gain change - a single multiplication of the data by a constant, than a 24 bit DSP machine is fine (in fact, with a lot of margin). The problems appears when you do hundreds or more computations. One such problem - each (single) computation makes for a tiny error. You keep doing more and more computations and the errors "pile up" and you get a combined error that is too large. Another such problem is the fact that many computations are a sum of many tiny elements that each one is very tiny (requires a lot of bits). You can later truncate the end result to say 24 bits, but first need to keep the individual elements to high precision.

This is a whole subject by itself. The point is - for DSP you do need to be ready for a lot of "extra" bits, depending on what you specifically need to do.

But 32 bits for conversion? Forget it! Say I get 1 volt out of a mic (that is a lot of signal!) for 24 bits, I need to have about 63 nano volts of noise (over the audio - I am assuming 22KHz bandwidth) the noise generated by a 2.5 KOhm resistor. So you are asking a mic to provide 1 volt into 2.5 KOhms - .4 mWatt free power and the limiting factor will be the resistor and nothing else. Try for 32 bits (192dB dynamic range): The noise requirement is now 0.25 nano volts, which would be generated by a single 4 Ohms resistor! So yes, make me a mic that can supply say .4 milliwatt of noise free signal into a 4 Ohms resistor, than have a mic pre amplifier with no noise at all and we are there Smile


BR
Dan Lavry  
Lavry Engineering

Title: Re: George....what's the resolution of analog?
Post by: danlavry on July 01, 2004, 02:35:40 pm
danlavry wrote on Thu, 01 July 2004 19:28

Johnny B wrote on Thu, 01 July 2004 08:02

Dan,
Are you saying that real improvements could be made by going to 32-bit converter chips?  
Sure some of those 32 bits could be wasted, but those extra bits could come in handy, at some point down the road, ya never know... LOL.



Correction:

I said (for 32 bits)

So yes, make me a mic that can supply say .4 milliwatt of noise free signal into a 4 Ohms resistor, than have a mic pre amplifier with no noise at all and we are there Smile

I Should have said "make me a mic that can supply say 1/4 watt (1 volt into 4 Ohms) of noise free signal into a 4 Ohms resistor... That 32 bit was carzy enough at any power level, but .4 watt was the wrong number so I am correcting it. Sorry, i did it too fast thus the error.

BR
Dan Lavry  
Lavry Engineering



Title: Re: George....what's the resolution of analog?
Post by: lucey on July 01, 2004, 03:17:24 pm
Nika Aldrich wrote on Wed, 30 June 2004 09:37

lucey wrote on Wed, 30 June 2004 06:04



Steve, I admit to a limited understanding of the subtle technicalities of digital recording.  I do know tone however, and specifically I know vibrations.


I am not surprised that you hear differences between analog and digital systems.  I've heard your music and work you've mixed, and my personal observation is that you tend toward very rich sounding analog material and equipment.


Anyone I know can hear the difference Nika, what are you implying?  

Yes I do produce music by recording analog instruments on analog gear, up until the final mastering step if possible.

(as for my work you've heard one or two older mixes that were poor by current standards.  you've heard no recordings made in the last 3 years, nor any mastering work)



Quote:


Quote:

To my ear any AD DA (even my amazing Pacific Microsonics) is fundamentally altering the waveform's quality.


Perhaps the PMi DOES alter the waveform's quality.  How have you tested it and what other converters have you tested - and how?

Nika


a) Everything alters the waveform, analog alters it quantitatively, digital alters the quality.   The Pacific is the most beautiful and accurate I've heard (have not heard Prism or Lavry, and dont need to a this point)

b) by listening
Title: Re: George....what's the resolution of analog?
Post by: Nika Aldrich on July 01, 2004, 03:47:30 pm
lucey wrote on Thu, 01 July 2004 20:17

what are you implying?  

(as for my work you've heard one or two older mixes that were poor by current standards.  you've heard no recordings made in the last 3 years, nor any mastering work)


Brian,

Just to be clear, I was not implying anything at all.  I have heard your work and I noticed that the artistic flavor you work toward is a very "analog-y" sound.  The tone was very rich and full, saturated at times, thick, sometimes heavy, big and round sounding.  I am drawn to the conclusion that this is your personal taste and that you aspire toward this sound.  I am led to this conclusion because I know that you have a lot of equipment and that you are very particular about your investments in your equipment.  I also know some of your equipment and know that you can get various colors out of it depending on how you use it.  Since you know this equipment well I am led to the conclusion that you intentionally color the music a particular way - not because you have to - but because that is how you like it.

Let me repeat that - I respect your ears and your abilities enough that I draw the conclusion that you are pleased with your results and that you like the particular coloration that you get in your recording/mixing process.  Ergo, my earlier statement was to draw no valuation on the *quality* of your mixes and was only to explain that, based on what I have heard, I would assume you would prefer analog equipment because it is easier to get the sound you like from that equipment.  That sound is "more available" with analog equipment at this time.  

There is no need to defend your work, and I doubt there is much purpose in me hearing your other work.  I have heard enough of your work to understand what it is that you like stuff to sound like that I have to assume your recent work does not contrast that much in terms of the overall color.  I don't think my conclusion would be any different today.  Again, no valuation of the quality of your work one way or the other - just observation.  Believe me, I don't play the "yeah, well I've heard your work and you don't have any grounds to talk" game.

Cheers,
Nika.
Title: Re: George....what's the resolution of analog?
Post by: Scovi on July 01, 2004, 07:39:46 pm
Oooo ... very juciy topic here folks. Thanks for the great read. My feeling is there are two questions/topics being addressed here. i.e "Which sounds better" and "which is more accurate"? I aggree with the concept previously presented of "which format is introducing more error?" Surely analog in the grand scheme of things is introducing more "error" if comparing input to output in the given system. But obviously there are some aritfacts of "analog errors" that we as listeners are either accustomed to, or just down right enjoy. The same does not seem to hold true for digital, in that we don't seem to have the same love for "digital errors". In fact, we seem to hold it to a higher standard ... and that standard is "it has to sound at least as good as analog" Anybody feel like we are there yet???
hmmm ... feel like I could ramble on for hours about this ... I'll spare you.

Scovill out
Title: Re: George....what's the resolution of analog?
Post by: danlavry on July 02, 2004, 09:40:11 pm
[quote title=lucey wrote on Thu, 01 July 2004 20:17][quote

You said
"Everything alters the waveform, analog alters it quantitatively, digital alters the quality.   The Pacific is the most beautiful and accurate I've heard (have not heard Prism or Lavry, and dont need to a this point)"

I say:
Hi, I am Dan Lavry and I wish you listened to a Lavry Smile The fact that you hear “even” the Pacific M you like is not surprising to me. I know their AD is a module made by Analogic, and we (I was employed by Silicon General) used to compete with them in non audio applications with the same sub-ranging architecture. It is a good approach, though somewhat noisy, and will have some unique color. When it comes to their DA’s, I know all about it. I designed that segment DA many years ago at Silicon General (the division was Analog Solutions). Later, a few folks started Ultra Analog and “took” that design and repackaged it. It eventually ended up at various places such as Mark Levinson gear that buys the DA modules. Years later, I reviewed the shortcomings of that approach (such as the weakness of PCM around digital black, the lack of deglitcher circuitry, the variations of components over temperature, component ageing and more), and I redesigned a much more segmented DA with far superior jitter rejection and a few other totally proprietary concepts.

Yet, how transparent is my best DA? How does it compare to analog? That is for the listener to decide. The first point to make is that there is analog and there is analog. Some is harsh, some is warm…. But I do appreciate your approach, to go as far as you can in analog. At some point, digital has some real advantages too – it does not scratch like vinyl, it does not demagnetizes or stretches, it is easy to copy and mass produce…. Other than that, I too love analog. We just can not ignore digital, and need to keep making it better. We have come a long way, in my opinion. I agree that digital has some unique problems and issues that do not come with analog.

BR
Dan Lavry  


Title: Re: George....what's the resolution of analog?
Post by: lucey on July 03, 2004, 10:34:59 am
danlavry wrote on Fri, 02 July 2004 20:40


I say:
Hi, I am Dan Lavry and I wish you listened to a Lavry Smile



Well, the price of this was right for me, and I love it, so ...

As for tone.  The Model One was in the shop before i bought it from Trevor, and they do upgrade both analog and software, and totally reset the specs any time they see a box for service... so that's cool.

Yet assuming your process improved upon the AD and DA of the Pacific, which makes sense, as time has passed, what about the analog path itself?

The Model Two was discontinued due to parts supplies on the Class A stuff they needed drying up.

Are your boxes chip laden?  If so, with ICs?  And how do the two levels vary in analog and converter path?
Title: Re: George....what's the resolution of analog?
Post by: Johnny B on July 03, 2004, 05:47:08 pm
Dan,

You used some of the following words:

truncation
conversion errors
not a full 24 bits
errors piling up

Or expressed those ideas for problems, right?

So what do you need at the chip level
for it to be done the right way?

In other words, couldn't the chips be made better so these errors don't exist and would not that be better? I dunno?




Title: Re: George....what's the resolution of analog?
Post by: danlavry on July 03, 2004, 09:05:25 pm
You said:
"Dan,
You used some of the following words:
truncation
conversion errors
not a full 24 bits
errors piling up
Or expressed those ideas for problems, right?
So what do you need at the chip level
for it to be done the right way?
In other words, couldn't the chips be made better so these errors don't exist and would not that be better? I dunno?"

Of course the chips can be done better, and the idea is to know where the next thing is to improve. It is a very big question!

Some of it has to do with the standard itself. The limitations of 16 bits (red book) call for processes such as dither to avoid truncations and noise modulation, but when you go for say 24 bits (DVD Audio), you can forget about such dither. With 441.KHz (CD) you are better off to noise shape the dither, but with say 88.2KH or 96KHz, you have a huge range where to “park” the truncation problems. So your noise shaping problem become an easy one to accomplish.

Some of it has to do with processes and resources. Say you need a hack of a lot of digital computations. It is more likely to be able to do a good job when you take an IC that is “specialized” at doing huge amount of processing and nothing but that, and put it together with another IC that does say just the DA function…

You see, the IC makers often try to cram a whole bunch of stuff into a single IC solution. The whole thing must be limited in space to something the size of a pin head, and it is running “boiling hot” at say 2 watts or so. Than someone “glues it” into a board that fits on a 19 inch rack… Well, yes, there are some support IC’s and often a display and some large connectors… But fundamentally, there is the question at hand: why cram a whole function into an single IC?

Much of the answer is about mass production and selling a complete cost effective solution. I am often amazed at who well the IC makers do things, given their constraints. But is it the best way to go? For mass production and cost effectiveness, the answer seems to be yes. For highest quality? Probably not so.

You see, The IC maker must produce solutions WHILE BEING CONSTRAINED to their own technology. True, their technology offers a lot of advantageous, but also there are a lot of things they simply can not do inside the IC. Anyone familiar with the game of Chess knows that there are only a few basic pieces (King, Queen, Bishop, Knight… Pawn). In electronics we have resistors, capacitors, indictors, semiconductors… I (an equipment designer) can use a whole range of resistor, capacitor and inductor values, and I can also choose them according to properties (the material they are made of and so on).  They (the IC designer) are playing the game with a lot less flexibility. They do not have ANY inductors inside the IC. They have almost no space for capacitors inside, only for very tiny value caps, of certain limitd material. For the most part, they often can not handle high voltage or current or much power and so on. Some of their world does offer advantageous the equipment designer is longing for (such as – all parts are so nearby, thus at almost the same temperature, thus they track well, laser trimming for great matching of parts, and so on).

We all end up knowing that the best design is a hybrid of IC and non IC technology. Going for quality, say a design calls for some poly capacitor. The smart IC designer will provide a pin or two to connect an external poly cap (The Cap may be much bigger than the whole IC) .The best IC technology for say a sigma delta DA may be best done with some semiconductor process, 5V supply and so on, that is NOT best for some other function. So you have a different IC process for an OPamp, say for a +/-15V supply, and so on…

To complicate things, all of it, inside and outside the IC, is based on theory, understanding of networks, circuits, signals, math and more. These days, I believe you will get the best quality when the IC guys do what they do best, and stop short of trying to go beyond their limitations. At that point, the equipment designer takes over, and with freedom from the limitations imposed on the IC designers and chip makers, goes for a complete quality product, whatever it takes.

Obviously, this is not what takes place when the main goal is mass production and low cost solutions.  So I do not expect the IC maker to lead us in the direction of highest quality. Their bottom line is driven by large quantity production! It costs a huge amount to make a new IC, and they need the volume. I am not sure we should wait for the IC makers to provide all the leadership. I was sad to see them sell 192KHz audio sampling AD and DA. They know it is BS from science and engineering standpoint. Often it is the little guy (like I) that has to fight those king kong size companies to send them in the right direction. I made a lot of progress, man does it take a lot of non paid for work Sad

BR
Dan Lavry
Title: Re: George....what's the resolution of analog?
Post by: Johnny B on July 03, 2004, 10:42:40 pm
Dan.

Thanks for the decription of the problems and tradeoffs the IC makers and people such as yourself face. Maybe I did not ask the question well.

OK, you know what the problems are, would the ideal chip have more bits, if so, how many? How would you get rid of some of the problems, besides making it easier for a design artist such as yourself to slectively hang stuff off the chip?

Do we really need or desire a full 24 bits? What would happen if you had that? Would you still be in business, would your life be a little easier from the design aspect?

 
Title: Re: George....what's the resolution of analog?
Post by: danlavry on July 06, 2004, 01:13:24 pm
You said:

“Dan.
OK, you know what the problems are, would the ideal chip have more bits, if so, how many? How would you get rid of some of the problems, besides making it easier for a design artist such as yourself to selectively hang stuff off the chip?
Do we really need or desire a full 24 bits? What would happen if you had that? Would you still be in business, would your life be a little easier from the design aspect?”

I say:

I do not view what I do as “selectively hanging stuff off the chips”. I believe I am the only one that designed manufacture and sell some AD and a DA made from scratch – resistors based design, with a lot of new concepts. Some of the concepts have been copied by competitors and some will be later. So I still think you are weighting things a bit heavy on the IC side, and light on the equipment maker side, at least for quality state of the art gear.

But yes, for the main market, the IC makers are the key, especially when it comes to consumer gear.

Do we really need 24 bits “end result”? I do not think we need 144dB dynamic range. How silent things get? Say a sound proof room. How loud? Say 10 feet behind a 747 jet engine? It is still not 144dB…

But one may want to have a little margin over what you need in the real world. What do we get today? Take a state of the art mic preamp, and you find that for the most part we are around 125dBu (plus minus a couple of dB) noise floor (equivalent noise floor, reflected to the input after accounting for some gain).
The question is: how much gain do you use? Say your setting is 30dB gain, and that effectively gets your signal peaks to full scale of 24dBu. So we have 125+24-30= 119dB dynamic range, or about 20 bits. Say you have a hot mic and the singer is yelling at it so you only need 20dB gain. We now have 125+24-20=129dB dynamic range or about 21 bits…

So basically that is how you determine what is needed. You may wish to adjust my figures a bit, but we are not anywhere near 24 bits in our capabilities. The improvements will have to be done at the bottleneck, which is both the microphones and the input stage of mic preamp. We are limited by analog noise sources. A 62 Ohms at room temperature generates 1nV/sqrtHz which ends up as .14uV of noise (0-20KHz bandwidth). A 1KOhm yields about 4 times as much (over 1/2uV noise). So a mic that “looks like” a 1KOhm will need to put 1/2V signal “to be” 20 bits. For 24 bits it would need to put out 8V! Of course the other analog noise comes from semiconductors, and there is little out there that goes much less than 1nV/sqrtHz. There are some costly “tricks” to improve semiconductor noise by some, but than the resistor noise is still there…

I can think of one application where you could do away with such (microphone) constrains – synth sound source, but I just do not see it as a good reason for 24 bits (no vocals and really limited sounds).

So the limitations are in the mic and the preamp. Those are the bottleneck today, and they are analog. There are physical reasons why that semiconductor noise figures have not improved much in 25 years (I mentioned that 1nV/sqrtHz noise voltage or so, and there is also a very limiting noise current in the few pA/sqrtHz).

In the context of moving towards 24 bits:
You asked about what the IC makers can do? It is the ANALOG low noise area that needs improvements – it will advance both the mics and the preamps. Compare to that very difficult undertaking, adding bits on a compute engine is “a walk in the park”.    

In the context of exsisting mics and preamps:
The AD and DA IC’s are not yet 24 bits, though some are specified as “20 bits A weighting”. They could and will improve it, and the job will be easier when we get rid of that 192KHz un needed burden.

In the context of what we need:
It would be great to have 21 bits AD noise floor, non weighted, out of an IC. Do we need more? I am not convinced we do. The final product is often less than 100dB dynamic range, and that can sound great. So that extra 20-30dB are there because it gives you margins to overcome all kinds of deterioration due to processing (gains and boosts and mixing and so on). This is not my area of expertise. I am an equipment maker.

You ask tough questions, thus the long answers…

BR
Dan Lavry

Title: Re: George....what's the resolution of analog?
Post by: Johnny B on July 06, 2004, 01:54:33 pm
Dan,

Yes, some questions are harder than others, I do not envy being in your position one bit.

Let's set the mics, preamps, and speaker issues aside for the moment, Ok? Let's also set aside the dynamic range issues aside as well, Ok? Just for the moment.

I'd like you to focus purely on the digital side of things for a moment since you brought up some error issues.

If you had 32-bit chips, would that help in any way?  Any way at all?

Also, picture this for a second, could you use the extra bits, (assuming you had them left over after the programmers were done and did not use every available bit like they often seem to do) to aid in adressing or routing functions? Would it be a good idea to be able to route signals around to different places. Could be a dumb idea, I dunno.

I only have two brain cells left, so forgive me if I'm being really stupid.

   
Title: Re: George....what's the resolution of analog?
Post by: danlavry on July 06, 2004, 02:31:06 pm
The number of digital bits (forget the analog)?

Here is a copy of what I wrote a few massages back:

"2. The number of bits used for digital signal processing (DSP). This is another issue all together.

Of course the initial reaction is: why 32 bits DSP if the signal is already below 24 bits? Why will we not have the analog noise "walk all over" the very low quantization noise of the DSP?

Of course, if all you wanted is say gain change - a single multiplication of the data by a constant, than a 24 bit DSP machine is fine (in fact, with a lot of margin). The problems appears when you do hundreds or more computations. One such problem - each (single) computation makes for a tiny error. You keep doing more and more computations and the errors "pile up" and you get a combined error that is too large. Another such problem is the fact that many computations are a sum of many tiny elements that each one is very tiny (requires a lot of bits). You can later truncate the end result to say 24 bits, but first need to keep the individual elements to high precision.

This is a whole subject by itself. The point is - for DSP you do need to be ready for a lot of "extra" bits, depending on what you specifically need to do."

More bits for DSP can be a total waste or extremely helpful, and it really depends on the application. I often use 56 bit accumulator machines fixed word length (Motorola) knowing it is often an overkill. But I once had an application that required me to break the data into 3 ranges (emulating a 56 bit floating point) all in double precision! The amount of precision really depends on the application, and one can figure "ahead of time" what word length is needed for each application. But say you know you need 29 bits, or 37 bit... The IC makers do not sell you a 29 bit or a 37 bit machine. They often come at multiple of 8 (8 bit is a byte). For example, there is a 32 bit floating, or a 56 bit fixed, or a 24 bit fixed...

Clearly audio requires precision so 24 fixed is out. 32 floating is good for a lot, and at times better precision is a big plus...

I do not think we are talking about an issue that is a technological chalane. The reason they pick 32 bit floating or 56 fixed it is because it is a good compromise. If there was a real need for 128 bits, they could do it!

I personally think we are getting closer to be able to replace much of the DSP ready made IC's functionality with FPGA (field programmable gate arrays), some can be programed at the factories at pretty small quantities. Altera and Xilinx are great examples for companies going in that direction. When you roll your own, you can control the word length as you please. We are not there yet but getting close to it. This is just my opinon...

BR
Dan Lavry





Title: Re: George....what's the resolution of analog?
Post by: Thomas Lester on July 13, 2004, 03:27:41 pm
Agree that it's not "better or worse".   It's different.  We hear analog every second of our lives...  that's why digital sounds different to us.  

As far as noise floor goes...  I worked in a large office environment once (a large cube farm).  The noise from all the phone chatter was unbearable to most and they got head aches and couldn't concentrate on their jobs.  So...  they brought in an acoustician to kill the noise.  I expected him to put up acoustic tiles, traps, etc...  

Nope...  he actually ADDED to the noise.  He put in ceiling speakers all around the place and piped white noise at a very low volume through the speakers.  It was low enough that you barely heard it (an that was only while working late after everyone went home).  

The complaining stopped and everyone was happy.  I asked him why, and basically it was enough "noise" to convince your brain to ignore the bad sounds in the room (i.e. other people talking).  

I'm guessing the noise floor in analog is what makes it sound so good or the lack there of in digital is why it doesn't sound "right" to us.

-Tom
Title: Re: George....what's the resolution of analog?
Post by: ted nightshade on July 13, 2004, 03:54:40 pm
Speaking of noise, I'm enjoying the rather high levels of ambient noise I'm getting recording where I am- you definitely know when the playback is happening, there's a goodly noise floor, most of it "room tone". That's very reassuring for some reason. Makes it easy to tune in- the room tone lets you know a lot about what you are about to hear. It's natural to make some preparations in your head, consciously or not, based on that bit of room tone and noise before the music kicks in. Also, it gives you a reference by which to judge dynamics- when you start hearing noise and ambience, you know it's pianissimo. I find this very pleasant and far preferable to a "black" background. I have always had trouble with the dynamics in digital (ff just seems too easy- no sense of work done), but doing these digital recordings with a bunch of ambience and natural noise seems to make it easier to get a feel for the dynamics with more excitement- things leap out relative to something else, and seem to leap out further as a result.

BTW, Dan, thanks again for all your participation here!
Title: Re: George....what's the resolution of analog?
Post by: bluespark on September 05, 2004, 05:16:47 pm
Loco wrote on Tue, 25 May 2004 18:24


It's not that those boxes are bad. They sound good. Maybe it's just they don't sound all that money. You can improve your sound a lot more putting your money somewhere else.


Sorry to dig up this oldie, but I think this should be a mantra for our entire field.


------

Daniel P Gardop
Title: Re: George....what's the resolution of analog?
Post by: Sjoko on September 04, 2005, 12:06:38 pm
Brent wrote on Sat, 15 May 2004 15:08

My World wrote on Sat, 15 May 2004 03:13

I have been "begging" sound processing companies for several years to develop 28-bit processors!  C'mon guys!


I believe that there is a 28-bit processor.  But it is not a true usable 28-bit any more than a 24 is really 24.

Lets say that they get to 32, so that it performs at 28.  Will the microphones used to record hinder the process?



The only available 28 bit converter I know of is the Stagetec Nexus, a stage gaining converter which converts to 28 bit.
The key advantage of this converter is that it keeps the integrity of the signal intact throughout the dynamic range, where in "normal" converter technology the lower levels of a recording get messed up.
This "difference" becomes a big, easy to hear factor when recording acoustic instruments in particular.  To my ears this converter is the only one that adequately represents the reality of the audio you try to capture (providing, of course, the million plus other factors involved).
I have had them for a number of years, and the only problem I've had is that other factors pop their evil heads up - as in I had to replace all wiring to keep the signal intact etc.
Next move will be to move the mic converter boards into the tracking rooms to minimise distance.
Title: Re: George....what's the resolution of analog?
Post by: CCC on September 04, 2005, 12:59:55 pm
Sjoko wrote on Sun, 04 September 2005 17:06

Brent wrote on Sat, 15 May 2004 15:08

My World wrote on Sat, 15 May 2004 03:13

I have been "begging" sound processing companies for several years to develop 28-bit processors!  C'mon guys!


I believe that there is a 28-bit processor.  But it is not a true usable 28-bit any more than a 24 is really 24.

Lets say that they get to 32, so that it performs at 28.  Will the microphones used to record hinder the process?



The only available 28 bit converter I know of is the Stagetec Nexus, a stage gaining converter which converts to 28 bit.
The key advantage of this converter is that it keeps the integrity of the signal intact throughout the dynamic range, where in "normal" converter technology the lower levels of a recording get messed up.
This "difference" becomes a big, easy to hear factor when recording acoustic instruments in particular.  To my ears this converter is the only one that adequately represents the reality of the audio you try to capture (providing, of course, the million plus other factors involved).
I have had them for a number of years, and the only problem I've had is that other factors pop their evil heads up - as in I had to replace all wiring to keep the signal intact etc.
Next move will be to move the mic converter boards into the tracking rooms to minimise distance.



Happy one-year anniversary, thread!
Title: Re: George....what's the resolution of analog?
Post by: Sjoko on September 04, 2005, 02:35:27 pm
time for a 28 bitproof drink Cool
Title: Re: George....what's the resolution of analog?
Post by: Ronny on September 04, 2005, 11:59:31 pm
Sjoko wrote on Sun, 04 September 2005 12:06

Brent wrote on Sat, 15 May 2004 15:08

My World wrote on Sat, 15 May 2004 03:13

I have been "begging" sound processing companies for several years to develop 28-bit processors!  C'mon guys!


I believe that there is a 28-bit processor.  But it is not a true usable 28-bit any more than a 24 is really 24.

Lets say that they get to 32, so that it performs at 28.  Will the microphones used to record hinder the process?



The only available 28 bit converter I know of is the Stagetec Nexus, a stage gaining converter which converts to 28 bit.
The key advantage of this converter is that it keeps the integrity of the signal intact throughout the dynamic range, where in "normal" converter technology the lower levels of a recording get messed up.
This "difference" becomes a big, easy to hear factor when recording acoustic instruments in particular.  To my ears this converter is the only one that adequately represents the reality of the audio you try to capture (providing, of course, the million plus other factors involved).
I have had them for a number of years, and the only problem I've had is that other factors pop their evil heads up - as in I had to replace all wiring to keep the signal intact etc.
Next move will be to move the mic converter boards into the tracking rooms to minimise distance.



Yamaha PM1D, 28 bit ADC's, 27 bit DAC's.
Title: Re: George....what's the resolution of analog?
Post by: Sjoko on September 05, 2005, 11:22:59 am
Yup Ronny, you're right, but it ain't no recording gear, just something lacking a decent clock Smile

Title: Re: George....what's the resolution of analog?
Post by: Ronny on September 05, 2005, 10:21:46 pm
Sjoko wrote on Mon, 05 September 2005 11:22

Yup Ronny, you're right, but it ain't no recording gear, just something lacking a decent clock Smile





It's mainly an FOH board, but many, many live recordings have been made off of them. The tower can run 8 MY8-AT's which gives 64 channels of ADAT. Clock is excellent.
Title: Re: George....what's the resolution of analog?
Post by: Ronny on September 05, 2005, 10:24:43 pm
Thomas Lester wrote on Tue, 13 July 2004 15:27

Agree that it's not "better or worse".   It's different.  We hear analog every second of our lives...  that's why digital sounds different to us.  

As far as noise floor goes...  I worked in a large office environment once (a large cube farm).  The noise from all the phone chatter was unbearable to most and they got head aches and couldn't concentrate on their jobs.  So...  they brought in an acoustician to kill the noise.  I expected him to put up acoustic tiles, traps, etc...  

Nope...  he actually ADDED to the noise.  He put in ceiling speakers all around the place and piped white noise at a very low volume through the speakers.  It was low enough that you barely heard it (an that was only while working late after everyone went home).  

The complaining stopped and everyone was happy.  I asked him why, and basically it was enough "noise" to convince your brain to ignore the bad sounds in the room (i.e. other people talking).  

I'm guessing the noise floor in analog is what makes it sound so good or the lack there of in digital is why it doesn't sound "right" to us.

-Tom


This is an old post but thought I'd respond anyway as I find the method used at the office interesting. The sound tech dithered the room.
Title: Re: George....what's the resolution of analog?
Post by: dcollins on September 05, 2005, 10:46:29 pm
Ronny wrote on Sun, 04 September 2005 20:59


Yamaha PM1D, 28 bit ADC's, 27 bit DAC's.



Naturally, anything claiming more than 20 "real" bits is subject to questions........  


http://www.yamaha.com/yamahavgn/Documents/ProAudio/pm1d_Broc hure.pdf


DC
Title: Re: George....what's the resolution of analog?
Post by: maxdimario on September 06, 2005, 05:47:20 am
now I'm gonna ask a very simple question, and I'd like some comments from you guys technical and non technical.

Why is it that when I listen to an analog recording with a chain consisting of: tube mic in perfect shape, tube pre (or exceptional low feedback solid state), discrete or tube analog recorder... I can hear the feel of the music more evidently than the equivalent path with digital recording?.

It sounds like a real person in the room with you, especially when reproduced on a good amp.


There must be an electronic distortion in the digital process that plays with what makes a sound realistic to our sense of hearing.

let's leave easily audible distortion out of it and focus only on the phsycological effect, please.

what could it be?
Title: Re: George....what's the resolution of analog?
Post by: Bob Olhsson on September 06, 2005, 09:44:41 am
I don't experience this same problem with high-end digital gear. Most digital gear is cheap and sounds cheap.
Title: Re: George....what's the resolution of analog?
Post by: Sam Lord on September 06, 2005, 11:01:11 am
maxdimario wrote on Tue, 06 September 2005 05:47

now I'm gonna ask a very simple question, and I'd like some comments from you guys technical and non technical.

Why is it that when I listen to an analog recording with a chain consisting of: tube mic in perfect shape, tube pre (or exceptional low feedback solid state), discrete or tube analog recorder... I can hear the feel of the music more evidently than the equivalent path with digital recording?.

It sounds like a real person in the room with you, especially when reproduced on a good amp.


There must be an electronic distortion in the digital process that plays with what makes a sound realistic to our sense of hearing.

let's leave easily audible distortion out of it and focus only on the phsycological effect, please.

what could it be?


Hey Max, I experience this on every 16-bit recording of moderately complex music I have.  All of my CDs of music with more than about two performers, and this includes many lauded albums, have a distinct lack of transparency and usually other sonic problems compared great recordings on pristine tape and (admittedly noisier) LPs.  But a number of orchestral SACDs (don't own any DADs or DVD-As yet) really do it all for me.  My brief work with my own 24-bit recordings and supporting testimony tells me that DSD, 24/96, and perhaps all 24-bit media can really hit the ball out of the park with truly fine recordings and playback systems, IMO.  Regards, Sam    
Title: Re: George....what's the resolution of analog?
Post by: Ronny on September 06, 2005, 12:32:10 pm
maxdimario wrote on Tue, 06 September 2005 05:47

now I'm gonna ask a very simple question, and I'd like some comments from you guys technical and non technical.

Why is it that when I listen to an analog recording with a chain consisting of: tube mic in perfect shape, tube pre (or exceptional low feedback solid state), discrete or tube analog recorder... I can hear the feel of the music more evidently than the equivalent path with digital recording?.

It sounds like a real person in the room with you, especially when reproduced on a good amp.


There must be an electronic distortion in the digital process that plays with what makes a sound realistic to our sense of hearing.

let's leave easily audible distortion out of it and focus only on the phsycological effect, please.

what could it be?



Digital is cleaner with high end systems. It's the analog distortion that is euphonic to your ears, not that the digi distorts more. The whole deal is you have to mix digital different than analog. It's typically going to be naturally brighter, doesn't matter if it's 24 bit. If converters are good quality, the only difference between 16 bit and 24 bit is the noise floor. The noise floor of 16 bit is 15dB lower than the self noise of the best Neumann mic.
Title: Re: George....what's the resolution of analog?
Post by: bobkatz on September 06, 2005, 03:40:45 pm
Ronny wrote on Mon, 05 September 2005 22:24


This is an old post but thought I'd respond anyway as I find the method used at the office interesting. The sound tech dithered the room.




Actually, it's called "noise masking". And it is a science as well as an art. I once encountered an ignorant technician who put so much noise into the speakers it became annoying. The key is to make the continuous random noise mask the specular impact noise or talking and machines (and in the old days, typewriters) in the room. Just enough.

Same principle as restaurants that play background music actually seem quieter! It masks the sound of the waitresses dropping the silverware. Smile

BK
Title: Re: George....what's the resolution of analog?
Post by: maxdimario on September 06, 2005, 03:57:26 pm
Quote:

It's the analog distortion that is euphonic to your ears


no, that's not what I'm talking about. I'm talking about the human element coming through.

Quote:

I don't experience this same problem with high-end digital gear. Most digital gear is cheap and sounds cheap.


well, you should know, since you've worked with great artists, tube gear and analog recorders.

I've never experienced the same kind of vibe, but my experience only goes up to prism converters, which are pretty high-end, as far as relative cost.

I did eye an old grundig tube 1/4" mono portable tape recorder that had a recording of some german woman reading a text, and on that cheap consumer setup, the voice was so real I did a double take looking for the source.

with analog you get the vibe for cheap, who knows how good it can get for 5000 dollars for a home analog reproducer, vs. the digital alternative.

anyway I don't wish to conjure up the usual arguments.

what my question was founded on was to try and identify the single most damaging distortion that ...Bad... digital seems to have inherently, which causes it to sound lifeless, cold and unfriendly compared to it's analog equivalent.

Title: Re: George....what's the resolution of analog?
Post by: Bob Olhsson on September 06, 2005, 10:54:46 pm
I think the most damaging distortion comes from not leaving enough headroom. A lot of digital gear simply hasn't got enough analog headroom to work with full-scale signals.

The first solid state mike preamp that I thought really stood up to the tube preamps we used at Motown was a prototype that my friend Pat Duran built for Deane Jensen. It clipped at something like +40. Upon realizing headroom was a common problem, I began experimenting with lower line levels and haven't looked back. I'm finding the same issues with digital multitracking. A lot of gear doesn't sound very good when you get within 6 dB of the top.
Title: Re: George....what's the resolution of analog?
Post by: Ronny on September 07, 2005, 01:50:51 am
Bob Olhsson wrote on Tue, 06 September 2005 22:54

I think the most damaging distortion comes from not leaving enough headroom. A lot of digital gear simply hasn't got enough analog headroom to work with full-scale signals.

The first solid state mike preamp that I thought really stood up to the tube preamps we used at Motown was a prototype that my friend Pat Duran built for Deane Jensen. It clipped at something like +40. Upon realizing headroom was a common problem, I began experimenting with lower line levels and haven't looked back. I'm finding the same issues with digital multitracking. A lot of gear doesn't sound very good when you get within 6 dB of the top.


What is the physical reason for not getting a good sound above -6dBFs, Bob? Not that I'm a stickler for squeezing every bit out, especially at 24 bit, but you'll find a trainload of people on the net that say you get a better sound when you are as close to -0dBFS as possible. My personal tests have shown me that there is no difference in audio quality between -20 and -0dBFS and the best place to optimize sonics is on the analog side before the signal goes through the ADC.



Title: Re: George....what's the resolution of analog?
Post by: maxdimario on September 07, 2005, 06:30:49 am
Regarding the levels being kept low, fair enough.

there is another mistery, though. Why is it that the analog recording (with the above-mentioned signal path) still sounds more human and natural feel-wise when there is slight clipping.

I'm still convinced there is something beyond traditional distortion, induced by improper operating range etc.

Intuitively I 'see' it as a more or less fine sandy haze from 3 KHz up. and Image instability?


admittedly, the more expensive converters may not exhibit this problem as much, probably because of the incredibly long amount of time that it's taking for people to realize that placing 2 or three cheap opamps before and after a converter GUARANTEES that the sound is not up to high standards..

but there is still something misterious happening, thd and clipping aside, I believe.

to me that's the resolution that's missing. noise is not a problem.

plus digital noise is not really 'noise' is it? it's noisy, but it's a result of the digitization process. it's a mathematical by-product.  
Title: Re: George....what's the resolution of analog?
Post by: Eric Bridenbaker on September 07, 2005, 08:09:00 am
Paul Frindle has given a very comprehensive explanation as to as why it's a good idea to keep digital levels low, and why you can't always trust digital peak meters. It can be found here:

     http://recforums.prosoundweb.com/index.php/mv/msg/4918/0/64/ 4645/?SQ=14738cbb8d492e71f640277262efe15f

As far as that upper mid to high analog thing maxdimario is talking about, this might refer to what a lot of producers and engineers call "hair", part distortion, possibly some phase shift... It sits "on top" of the original sound, and can be used to enhance the perceived clarity and closeness of the sound. Hard to get this in digital, but it can be done, as in the HEDD unit.

When analog tape is driven, there is compression going on, particularly noticeable in the highs. Also, in some sources, especially drums there are these naturally occuring short transient peaks, about a millisecond or two in length, sometimes 10 to 15 dB higher that the rest of the signal. Analog tape will smooth these fast peaks right over, if driven hard enough. This, IMHO is a major part of what gives analog tape its sonic characteristics. Loud and soft at the same time, with a compression curve close in nature to the way the ear operates.

With an all analog path vs a digital one, I can hear a definite immediacy to the  sound with the analog, however the better digital converters get closer to this.

Cheers,
Eric
Title: Re: George....what's the resolution of analog?
Post by: bobkatz on September 07, 2005, 09:36:19 am
Ronny wrote on Wed, 07 September 2005 01:50




What is the physical reason for not getting a good sound above -6dBFs, Bob? Not that I'm a stickler for squeezing every bit out, especially at 24 bit, but you'll find a trainload





Ronny, it's not the dBFS that Bob O was referring to, but the internal headroom of the analog electronics around and inside the converters. I've written extensively about this. Firstly, many lower cost (and even higher cost) pieces of gear are not designed with good internal analog headroom ABOVE the digital peak point.

Some integrated circuit opamps that I've encountered over the years seem to start to sound "ratty" as they approach their clipping points, their distortion characteristics shoot up as they approach clipping, especially at high frequencies. It is not fair to generalize, since the expertise of the designer, power supply design, bias, etc. count. But if I were to generalize, I'd say that caution is warranted as you approach the clipping level of an opamp, especially an integrated circuit opamp. I've encountered MANY opamp-based circuits that sound a lot better when driven to a max of 6 dB below clipping, rather than within 1 dB of clipping, which is a common practice in many designs to try and get high output levels.

Of course this is not universally true. The increase in distortion as clipping is appraoched is dependent on the implementation, brand and type of opamp, power supply voltages, how the opamp is biased. Regardless, I suggest caution in any case, especially in mixed signal (digital and analog) environments if the clipping point of the analog circuitry is being approached along with 0 dBFS (and measured 0 dBFS+ overs as well) at the same time, it's a recipe for ratty sound.

I've built unbalanced IC-based mixers with + and - 18 volt power supplies, using Burr Brown and other high quality opamps and despite the pedigree, I found they just sound better running "0 VU" at lower than 0 dBu, even as low as -6 dBu (0.0775 volts). Clipping point of these, running unbalanced, is nominally +20 to +22 dBu.

Thus, we are finding balanced preamps of high quality now which clip at far above +24 dBu, as high as +37 in some cases. The term I've been using for this necessary "analog headroom above 0 dBFS" is a "cushion". It's not a very scientific term, but it's the best I've got. To summarize: you should never operate certain solid state gear close to clipping; align the clipping point of the analog gear to AT LEAST 6 dB above the 0 dBFS point of the associated digital circuitry.

As for "people on the net saying you get a better sound when you are as close to 0 dBFS as possible", I tend to disagree. Given the evidence above, I'd say that is a generality as close to "he said, she said" as I've heard. Please let's hear some specific quotes from individuals who have tested and listened and reached these conclusions. If I were to generalize, I'd disagree; I'd say that "in general", you're a lot safer peaking somewhat lower than to full scale, for some of the reasons I mentioned above, and in addition, inaccuracies of digital meters, 0 dBFS+ signals, etc.

BK
Title: Re: George....what's the resolution of analog?
Post by: David Glasser on September 07, 2005, 12:08:23 pm
bobkatz wrote on Wed, 07 September 2005 07:36



I've built unbalanced IC-based mixers with + and - 18 volt power supplies, using Burr Brown and other high quality opamps and despite the pedigree, I found they just sound better running "0 VU" at lower than 0 dBu, even as low as -6 dBu (0.0775 volts). Clipping point of these, running unbalanced, is nominally +20 to +22 dBu.




I have a Calrec mixer, mid 80s vintage,  that uses run-of-the-mill chips, but operates at -4dBu (ie, 4 db below 0 VU or 0 dBu). I've wondered if that's one of the reasons it sounds so good, despite the multitude of TL072s and NE5534s (which I will replace... someday).
Title: Re: George....what's the resolution of analog?
Post by: bobkatz on September 07, 2005, 12:44:14 pm
David Glasser wrote on Wed, 07 September 2005 12:08

bobkatz wrote on Wed, 07 September 2005 07:36



I've built unbalanced IC-based mixers with + and - 18 volt power supplies, using Burr Brown and other high quality opamps and despite the pedigree, I found they just sound better running "0 VU" at lower than 0 dBu, even as low as -6 dBu (0.0775 volts). Clipping point of these, running unbalanced, is nominally +20 to +22 dBu.




I have a Calrec mixer, mid 80s vintage,  that uses run-of-the-mill chips, but operates at -4dBu (ie, 4 db below 0 VU or 0 dBu). I've wondered if that's one of the reasons it sounds so good, despite the multitude of TL072s and NE5534s (which I will replace... someday).


It could be one of the reasons! Try running it hotter and see. The TLOs would be the first ones to replace.
Title: Re: George....what's the resolution of analog?
Post by: C-J on September 07, 2005, 02:25:39 pm
Eric Bridenbaker wrote on Wed, 07 September 2005 15:09

Paul Frindle has given a very comprehensive explanation as to as why it's a good idea to keep digital levels low, and why you can't always trust digital peak meters. It can be found here:

      http://recforums.prosoundweb.com/index.php/mv/msg/4918/0/64/ 4645/?SQ=14738cbb8d492e71f640277262efe15f
Bob Olhsson wrote on Wed, 07 September 2005 05:54

I think the most damaging distortion comes from not leaving enough headroom. A lot of digital gear simply hasn't got enough analog headroom to work with full-scale signals.

What that link, and Bob are talking about, is the distortion caused by "shootovers between samples" created in the DAC's reconstruction filter, isn't it?
Doesn't an oversampling peak meter provide an easy solution for this problem? I always use RME Digicheck's Stereo Meter in OVS mode, to set the "Out Ceiling" levels of L2. It seems to reveal a lot of redouts, although the L2 meter peaks below FS.

My best,
C.J., Finland
Title: Re: George....what's the resolution of analog?
Post by: Bob Olhsson on September 07, 2005, 09:19:26 pm
I think Bob Katz treats this issue very well.

Since I can't rebuild most of the gear I have to use, I simply take the time to find the sweetest sounding gain structure for the system I'm using.
Title: Re: George....what's the resolution of analog?
Post by: maxdimario on September 08, 2005, 05:38:07 am
OK.

so there is an ideal level for each of the various gain stages, and we want to keep the output low so that the amps are running below their limits to the point that they don't sound harsh or strident or dull etc.

I can understand that as much analog circuitry in converters is fed by low voltage rails, and uses op-amps.

solid-state semiconductors do not tolerate large voltage swings, as do tubes, which can be fed high levels of signal on the control grids.

all electronics audio circuits work more ideally when the operating level is low enough for the circuit to work comfortably, and high enough so that the noise floor is not an issue.

these are some very important points, which are often overlooked, and are a lost art.

....regarding the human feel factor and intimacy on analog vs. digital?

You've mentioned that to get the same feel out of digital you need to go for the 24 bit high-end converters..ok

how about the 1" two track at 30 IPS on a discrete recorder?

I am not wanting to begin the analog VS. digital thingy again.

Just curious if anyone else who can hear this feel-factor has an idea of what it might be.

promise I won't insist on this issue anymore..honest..
Title: Re: George....what's the resolution of analog?
Post by: Sjoko on September 09, 2005, 08:29:15 pm
Ronny wrote on Mon, 05 September 2005 19:21

Sjoko wrote on Mon, 05 September 2005 11:22

Yup Ronny, you're right, but it ain't no recording gear, just something lacking a decent clock Smile





It's mainly an FOH board, but many, many live recordings have been made off of them. The tower can run 8 MY8-AT's which gives 64 channels of ADAT. Clock is excellent.


Not arguing with you - but, just for fun, homor me, do what I did, and clock it with a good external clock. I think you would be in severe shock about the difference....
Title: Re: George....what's the resolution of analog?
Post by: Ronny on September 09, 2005, 09:52:45 pm


Infinity.
Title: Re: George....what's the resolution of analog?
Post by: dongle on September 10, 2005, 01:12:45 am
Nika Aldrich wrote on Thu, 24 June 2004 16:40

lucey wrote on Thu, 24 June 2004 16:31

It's as basic as asking yourself this ... if you were a kid which waterslide would you rather ride?

a) the smoothe and wet one with some friction and a few slight turns, or

b) the one with tiny stair steps and perfectly even friction, straight down?



Scientific minds are of great help to many aspects of music, but the scientific ear does not hear the subtleties of the stair steps as the catastophic loss of integrity that musicians hear.


Why are you ignoring the role of the reconstruction filter at the end of the D/A converter?

Digital does NOT have all of the stair-steps that you describe.  Digital is only a representation of the waveform - NOT the waveform itself.  The original waveform still has to be reconstructed from the sample points.  Simply doing a "dot to dot" or sample-hold reconstruction is clearly inadequate, as neither of those re-create the original waveform.  When proper reconstruction filtering is done there is no  "stair-stepping," and continuing to refer to such obfuscates the way in which digital actually works and confuses the questions.

Nika.



I love this man, and his comments, its hard to argue with him, because he speak only of facts.
Title: Re: George....what's the resolution of analog?
Post by: dcollins on September 10, 2005, 03:30:38 pm
Ronny wrote on Fri, 09 September 2005 18:52



Infinity.


Bzzzzzt!

DC
Title: Re: George....what's the resolution of analog?
Post by: jfrigo on September 10, 2005, 11:13:15 pm
dcollins wrote on Sat, 10 September 2005 12:30

Ronny wrote on Fri, 09 September 2005 18:52



Infinity.


Bzzzzzt!

DC


C'mon Dave... don't let reality get in the way. Talk of stairsteps and infinite resolution is way too much fun to let the facts stop you. Now where did I put my $400 wooden volume knob?
Title: Re: George....what's the resolution of analog?
Post by: skygod on January 04, 2009, 06:58:15 pm
Reality? Nineteen pages later to determine the resolution of analog lol. Hmmmm ... are we rapidly approaching a society of having our analog ears replaced by pcm 16->24 bit digital listening receptors instead? Imagine that will you, and all this time I thought the resolution of analog was the tomcat boinging the in-heat shreiking female cat back behind the building in the alley somewhere waking up the dead.  Maybe I need to get out there with a 1-bit recorder and capture that? Who knows ... maybe that'll lend some light on the true nature of analog resolution or will there be a problem differntiating between 1-bit recording made on the Korg MR-2000 or should I just stick to current PCM audio format @ 24/96 my sweet musical zone? Decisions decisions decisions ... Yup, yessiree Happy New Year everybody. I want you to be the first to send Happy New Year greetings... and as I reflect on 2008, I can say we had a great year:

Blacks are happy; Obama was elected.
Whites are happy, OJ is in jail.
Democrats are happy; George Bush is leaving office.
Republicans are happy: Democrats will finally quit saying George Bush stole the election.
And all of us are happy; The election is finally over!

2009 should be even better: Immediately after his inauguration, Obama will balance the budget, revive the economy, solve the real estate problem, solve the auto industry problem, solve our gas/alternative energy problem, stop the fires and mudslides in California, ban hurricanes and tornadoes, stop identity theft, reverse global warming, find Osama, solve the Israeli-Palestinian conflict, get rid of corruption in government and achieve world peace. Then on the 7th day, He will rest. Amen!

2009 has the making to become a glorious year. Best wishes for an all analog 2009!

~skygod~
Title: Re: George....what's the resolution of analog?
Post by: Nick Sevilla on January 09, 2009, 07:23:03 pm
jazzius wrote on Fri, 14 May 2004 09:56

George, we hear about the resolution of digital all the time.....24 bits, 44.1, 192.....2.8 million whatevers....

...do you know if anyone has ever worked out the resolution of analog?.....how many bits would it be equivelent to?.....i know this is bit of a strange question, but i'd love to be able to give my customers a smart-arse answer for why analog sounds better then digital...

...cheers.....Darius


I can give you a resolution for a 1974 8048 Neve desk I helped restore :

10 to 100,000 cycles from the line / mic inputs through to the mix buss. That's 10 Hz to 100KHz. this is better than all semi-pro and even some pro desks out there. The EQ modules in the desk specd' out to :

1066 EQ modules - 10Hz to 97500Hz (average from 18 modules). Older modules, and well within spec.

1081 EQ modules - 10Hz to 100,000 Hz (average for 36 modules).

Noise floor of -97 dB. A little better than CD quality, but not much.

THD of 0.5% using 1kHz tone at +23 dB, a little less than the original spec, but still usable headroom.

We only had a sine generator that went from 10Hz to 100,000Hz, so it could go higher and lower, but we kept referring to the original spec, and matched it.

Cheers,

Nick
Title: Re: George....what's the resolution of analog?
Post by: Andy Peters on January 11, 2009, 01:26:22 am
Nick Sevilla wrote on Fri, 09 January 2009 17:23

jazzius wrote on Fri, 14 May 2004 09:56

George, we hear about the resolution of digital all the time.....24 bits, 44.1, 192.....2.8 million whatevers....

...do you know if anyone has ever worked out the resolution of analog?.....how many bits would it be equivelent to?.....i know this is bit of a strange question, but i'd love to be able to give my customers a smart-arse answer for why analog sounds better then digital...

...cheers.....Darius


I can give you a resolution for a 1974 8048 Neve desk I helped restore :

10 to 100,000 cycles from the line / mic inputs through to the mix buss. That's 10 Hz to 100KHz. this is better than all semi-pro and even some pro desks out there. The EQ modules in the desk specd' out to :

1066 EQ modules - 10Hz to 97500Hz (average from 18 modules). Older modules, and well within spec.

1081 EQ modules - 10Hz to 100,000 Hz (average for 36 modules).

Noise floor of -97 dB. A little better than CD quality, but not much.

THD of 0.5% using 1kHz tone at +23 dB, a little less than the original spec, but still usable headroom.

We only had a sine generator that went from 10Hz to 100,000Hz, so it could go higher and lower, but we kept referring to the original spec, and matched it.

Cheers,

Nick


At the risk of lengthening a thread that was dormant for four years:

Frequency response is NOT resolution.

-a
Title: Re: George....what's the resolution of analog?
Post by: compasspnt on January 11, 2009, 10:13:02 am
Lengthen the thread.

Information needs to be further disseminated.
Title: Re: George....what's the resolution of analog?
Post by: Fig on February 06, 2009, 12:51:46 pm
Andy Peters wrote on Sun, 11 January 2009 00:26



Frequency response is NOT resolution.

-a


Hi Andy,

To be honest, I have been thinking about this topic since it was posted.  I have searched and searched for a definition of "resolution" as it pertains to audio - there is tons of BS regarding video, printers, faxes, photos, etc.

While I agree that the freq response only tells us part of the story - how WOULD someone go about determining the other aspects and coming up with an "answer" for "resolution"?

I'm picturing some kind of equation utilizing cycles-per-second (Hz) and inches per second (IPS) where maybe the "time" cancels out and perhaps cycles per inch somehow connected to the flux level, dynamic range, track width, blah-blah.

With your experience and knowledge, Andy, how would you go about generating such a spec?

Fig
Title: Re: George....what's the resolution of analog?
Post by: Tomas Danko on February 06, 2009, 01:09:47 pm
Fig wrote on Fri, 06 February 2009 17:51

Andy Peters wrote on Sun, 11 January 2009 00:26



Frequency response is NOT resolution.

-a


Hi Andy,

To be honest, I have been thinking about this topic since it was posted.  I have searched and searched for a definition of "resolution" as it pertains to audio - there is tons of BS regarding video, printers, faxes, photos, etc.

While I agree that the freq response only tells us part of the story - how WOULD someone go about determining the other aspects and coming up with an "answer" for "resolution"?

I'm picturing some kind of equation utilizing cycles-per-second (Hz) and inches per second (IPS) where maybe the "time" cancels out and perhaps cycles per inch somehow connected to the flux level, dynamic range, track width, blah-blah.

With your experience and knowledge, Andy, how would you go about generating such a spec?

Fig


This is a common misconception due to lack of understanding digital audio (which is often very counter-intuitive to grasp and in no small way). And this often translates into something similar when considering the analog world of audio.
Please bare with me for a while here...

When talking about digital audio one can say the following things:

Frequency response and transient/impulse response is tied together with bandwidth. (ie sample rate)
Resolution is tied together with dynamics. (ie bit depth)

Analog audio is continuous, and as such does not really conform to be measured in terms of "resolution". Just go for bandwidth instead, or when building a piece of analog audio equipment perhaps look at slew rates and technical implementation.

Then again, once the digitally recorded audio waveform has been reconstructed (ie what you hear after the DAC), it is also continuous. In other words, those individual numbers inside the DAW maybe lead one to believe that the audio has been chopped up and that it's going to affect playback. However, this is not the case. Those individual numbers are merely a middle stage for the entire process and not the final reconstructed waveform you hear.


It think we can keep continuing to refer to bandwidth and dynamic range in order to describe how much any analog carrier of sound will be able to accurately capture and reproduce.
Title: Re: George....what's the resolution of analog?
Post by: Fig on February 06, 2009, 01:33:52 pm
Tomas Danko wrote on Fri, 06 February 2009 12:09

Fig wrote on Fri, 06 February 2009 17:51

Andy Peters wrote on Sun, 11 January 2009 00:26



Frequency response is NOT resolution.

-a


Hi Andy,

<snip>

With your experience and knowledge, Andy, how would you go about generating such a spec?

Fig


<snip>
Please bare with me for a while here...


You must mean "bear" - we don't know each other that well Smile

Tomas, I fully grasp the fundamentals of digital audio (main reason I avoid it whenever possible).  I like my waveforms just the way they are, thank you very much - I mean, why chop a perfectly good sine wave into a million pieces just to try to put it back together again as closely as possible?

But the "analog resolution" inquiry remains unanswered.

I realize the concept of resolution came with the invention of digital (for better or worse).  And in my opinion, the two techniques are apples and oranges anyway, but if we WERE to put new concepts on old vehicles, what kind of "results" could we come up with?

My mind is already made up as to which I prefer and why.

Fig


Title: Re: George....what's the resolution of analog?
Post by: Jay Kadis on February 07, 2009, 12:20:59 pm
Resolution means the ability to unambiguously discriminate between two values.  The meaning for digital (sampled) systems relates to the quantization process, where discrete measurements are derived from a continuously varying amplitude.  In this case, resolution is limited by the size of the quantization step: once the amplitude drops below that coded by the LSB we cannot resolve differences.

In the case of continuous analog systems, the resolution is limited by the noise floor.  When the signal amplitude drops into the noise, it becomes a statistical process to extract the signal from the noise.  At some point the noise swamps the signal beyond any ability to extract the signal, so that would be the lower limit of resolution.  While analog audio systems lack the same sharp limit to resolution we find in digital audio systems, the resolution is not infinite, but must be determined statistically.

Adding dither to a quantizer makes the resolution dependent on statistical analysis as well, but no system has infinite resolution.
Title: Re: George....what's the resolution of analog?
Post by: Jon Hodgson on April 01, 2009, 08:30:08 pm
Actually analogue systems can have quantization errors too. When I met Tim De Paravicini (a man who certainly seems to know his cutting lathes) I was surprised to discover that the error caused by the fact that you can either have a vinyl molecule or not (so the resolution of a cut is +/- half a molecule) was only 90dB below full signal, I'd always assumed that the molecules were too small for that to be a consideration... it seems not.

The fact that you random variations in the matrix results in those errors being random and thus white noise.

It amused me somewhat to discover that vinyl is actually a dithered system with a quantization step size approximately equivalent to a 15 bit system.
Title: Re: George....what's the resolution of analog?
Post by: Jay Kadis on April 02, 2009, 10:55:50 am
Jon Hodgson wrote on Wed, 01 April 2009 17:30

Actually analogue systems can have quantization errors too. When I met Tim De Paravicini (a man who certainly seems to know his cutting lathes) I was surprised to discover that the error caused by the fact that you can either have a vinyl molecule or not (so the resolution of a cut is +/- half a molecule) was only 90dB below full signal, I'd always assumed that the molecules were too small for that to be a consideration... it seems not.

The fact that you random variations in the matrix results in those errors being random and thus white noise.

It amused me somewhat to discover that vinyl is actually a dithered system with a quantization step size approximately equivalent to a 15 bit system.
I'd like to hear more about the molecular size issue:  the 90 dB figure seems pretty high (or low?)    (The S/N of vinyl in practice falls significantly below 90 dB though.)  As I understand it "vinyl" is actually a vinyl chloride-vinyl acetate copolymer.  Wouldn't such a polymer would consist of particles of varying dimensions?

We have a similar issue in analog tape due to the finite dimensions of the individual magnetic domains.
Title: Re: George....what's the resolution of analog?
Post by: Jon Hodgson on April 02, 2009, 11:28:44 am
Jay Kadis wrote on Thu, 02 April 2009 15:55

Jon Hodgson wrote on Wed, 01 April 2009 17:30

Actually analogue systems can have quantization errors too. When I met Tim De Paravicini (a man who certainly seems to know his cutting lathes) I was surprised to discover that the error caused by the fact that you can either have a vinyl molecule or not (so the resolution of a cut is +/- half a molecule) was only 90dB below full signal, I'd always assumed that the molecules were too small for that to be a consideration... it seems not.

The fact that you random variations in the matrix results in those errors being random and thus white noise.

It amused me somewhat to discover that vinyl is actually a dithered system with a quantization step size approximately equivalent to a 15 bit system.
I'd like to hear more about the molecular size issue:  the 90 dB figure seems pretty high (or low?)    (The S/N of vinyl in practice falls significantly below 90 dB though.)  As I understand it "vinyl" is actually a vinyl chloride-vinyl acetate copolymer.  Wouldn't such a polymer would consist of particles of varying dimensions?

We have a similar issue in analog tape due to the finite dimensions of the individual magnetic domains.



I haven't looked into it in detail myself to confirm what he said, but I think anyone who's read Tim's bio would probably agree he's someone who knows about vinyl cutting, and anyone who's met him would agree that he can spout numbers like nobody's business... so I have good reason to find it quite likely that he's correct, especially since the figure he's apparantly calculated seems consistent with the sorts of numbers I'd already heard of for SNR on vinyl (he was quoting a very best case, the typical value would be less because you're not using the maximum signal level all the time and because of manufacturing issues and damage post manufacture), but obviously it shouldn't be taken as gospel without some further verification.

As for particles being of varying dimensions, this might be the case, I don't know, but if it is probably reasonable to use the largest size in order to make your calculation of SNR.

I had also thought about the analogue tape issue you mention, but have no figures on that, so I don't know if it is significant in real terms (just as quantization error isn't really significant in a 24 bit A/D conversion)


Title: Re: George....what's the resolution of analog?
Post by: Andrew Hamilton on June 29, 2009, 10:11:38 pm
Jon Hodgson wrote on Wed, 01 April 2009 20:30

Actually analogue systems can have quantization errors too.


Errors of truncation, when the lacquer molecules refuse to be cut in two.  Not a quantum "decision," though, since the molecule _can_ be cut in two.   Just a dance between inertia and momentum.  No sampling means no quantization, though, doesn't it?

Jon Hodgson wrote

When I met Tim De Paravicini (a man who certainly seems to know his cutting lathes) I was surprised to discover that the error caused by the fact that you can either have a vinyl molecule or not...


Aren't we talking about cellulose nitrate at the mastering lathe?  Vinyl (or pvc with black pigmentation) would be a pressing concern, no?

Jon Hodgson wrote

The fact that you [have] random variations in the matrix results in those errors being random and thus white noise.

It amused me somewhat to discover that vinyl is actually a dithered system with a quantization step size approximately equivalent to a 15 bit system.


So, the dynamic range is equivalent to that of a 14+ bit LPCM carrier?  No actual steps in analog, though, right?




Andrew
Title: Re: George....what's the resolution of analog?
Post by: Jon Hodgson on June 30, 2009, 01:29:00 pm
Andrew Hamilton wrote on Tue, 30 June 2009 03:11

Jon Hodgson wrote on Wed, 01 April 2009 20:30

Actually analogue systems can have quantization errors too.


Errors of truncation, when the lacquer molecules refuse to be cut in two.  Not a quantum "decision," though, since the molecule _can_ be cut in two.   Just a dance between inertia and momentum.  No sampling means no quantization, though, doesn't it?

Jon Hodgson wrote

When I met Tim De Paravicini (a man who certainly seems to know his cutting lathes) I was surprised to discover that the error caused by the fact that you can either have a vinyl molecule or not...


Aren't we talking about cellulose nitrate at the mastering lathe?  Vinyl (or pvc with black pigmentation) would be a pressing concern, no?

Jon Hodgson wrote

The fact that you [have] random variations in the matrix results in those errors being random and thus white noise.

It amused me somewhat to discover that vinyl is actually a dithered system with a quantization step size approximately equivalent to a 15 bit system.


So, the dynamic range is equivalent to that of a 14+ bit LPCM carrier?  No actual steps in analog, though, right?




Andrew


Ever tried to cut a molecule? I don't think you're going to do it with a chisel (which is effectively what a cutting lathe is).

Certainly Tim was of the opinion that you had a molecule or you didn't, which gives you an instantaneous error of +/- 1/2 a molecule (which is according to him, 90dB below the maximum deviation you would let the needle make).

This is actually a quantization, but you have a huge number of them per second, and they are all slightly off from each other, so can be considered random (I don't know about the distribution of the error, we might guess gaussian).

So there are steps in vinyl if you look at it closely enough, but we can view it as having no steps and some noise.

Which funnily enough is how dither works.
Title: Re: George....what's the resolution of analog?
Post by: Andrew Hamilton on July 02, 2009, 03:08:19 am
Jon Hodgson wrote on Tue, 30 June 2009 13:29


Ever tried to cut a molecule? I don't think you're going to do it with a chisel (which is effectively what a cutting lathe is).


The molecules in the lacquer may refuse to be cut by a mere heated wiggling blade...

...more nitro-cellulose? (;

If I add uncorrelated dither to an analog signal, that would make the signal have slightly more hiss, but I hesitate to call the result quantized audio, since the available amplitude modulation values are still continuous in scope.  Any error, as you have said, is heard as part of the noise floor, although at 90 dB into vinyl, I suspect that other surface noises are predominant.

Dither is supposed to be the remedy for the audibility of quantization error.  However, in your analogy, the molecular auto-dither is what's causing the "error."  

The lacquer molecule apparently randomly shunts the signal to heat(?) at the level of the randomly undulating noise floor of the cutting, in a way which emulates redithered digital audio.   I am not trying to keep comparisons  between analog and digital from happening, but, to me, the quantization term is a bit (; generous in this analogy (;.  

On a(n lp) master, for example, it's physically possible for the output signal to be of any arbitrary value within the dynamic range allowed by the lacquer, at any moment in time, in spite of the fact that the noise floor that is added to it is random, by +/- 1/2 lacquer molecule, when examined at its deep floor level, because the first term in the expression (analog audio) is continuously variable, unlike in quantized audio, so even if the second term in the expression (molecule/no molecule) is a constant, the result is still continuously variable.  

Whereas, in  quantized audio systems, such as LPCM, or DSD, the peak sample level of the digitized signal can only be up or down by one or more of the same, finite  amount(s) from  where it was at any given time prior.  By the time it no longer is digital, it's no longer quantized.  At least that's my layman's usage of the terminology.  





Respectfully,
    Andrew

Title: Re: George....what's the resolution of analog?
Post by: Jon Hodgson on July 02, 2009, 06:26:04 am
Andrew Hamilton wrote on Thu, 02 July 2009 08:08

Jon Hodgson wrote on Tue, 30 June 2009 13:29


Ever tried to cut a molecule? I don't think you're going to do it with a chisel (which is effectively what a cutting lathe is).


The molecules in the lacquer may refuse to be cut by a mere heated wiggling blade...

...more nitro-cellulose? (;

If I add uncorrelated dither to an analog signal, that would make the signal have slightly more hiss, but I hesitate to call the result quantized audio, since the available amplitude modulation values are still continuous in scope.  Any error, as you have said, is heard as part of the noise floor, although at 90 dB into vinyl, I suspect that other surface noises are predominant.

Dither is supposed to be the remedy for the audibility of quantization error.  However, in your analogy, the molecular auto-dither is what's causing the "error."


You're misunderstanding me a little.

The one molecule limit to accuracy is the quantization, if you had a perfect matrix of molecules and the time axis of your groove was along one axis of the matrix, your output would have steps one molecule high.

However the matrix isn't perfect, and the groove wouldn't be travelling straight across it if it was, so the quantization levels vary, in a random way, the dither is the variation in that quantization point. Normally we use dither by having a fixed quantization point and adding noise to our input signal, but mathematically it would work exactly the same if we left the input signal clean and randomly varied the quantization level.


Title: Re: George....what's the resolution of analog?
Post by: Jay Kadis on July 02, 2009, 10:38:10 am
The dimensions of a vinyl chloride molecule are on the nanometer scale.  Polymerized vinyl chloride chains may consist of hundreds to thousands of monomer units and complex side-chains may form producing a very complex molecule.  How the surface of a groove may interact with a stylus depends on the particular composition of the polyvinyl chloride and would be quite complex to analyze, requiring scanning electron microscopy to image the surface.

Given the dimensions of a stylus (microns), the molecular size of the particles themselves (nanometers) would not matter as much as the way the molecules pack together as there's a thousand-fold difference in size between the stylus and the surface molecular arrangement.  I doubt the stylus could follow individual molecules and would rather respond to the macro-level surface that would depend on the aggregation of vinyl molecules.
Title: Re: George....what's the resolution of analog?
Post by: Jon Hodgson on July 02, 2009, 09:44:32 pm
Jay Kadis wrote on Thu, 02 July 2009 15:38

The dimensions of a vinyl chloride molecule are on the nanometer scale.  Polymerized vinyl chloride chains may consist of hundreds to thousands of monomer units and complex side-chains may form producing a very complex molecule.  How the surface of a groove may interact with a stylus depends on the particular composition of the polyvinyl chloride and would be quite complex to analyze, requiring scanning electron microscopy to image the surface.

Given the dimensions of a stylus (microns), the molecular size of the particles themselves (nanometers) would not matter as much as the way the molecules pack together as there's a thousand-fold difference in size between the stylus and the surface molecular arrangement.  I doubt the stylus could follow individual molecules and would rather respond to the macro-level surface that would depend on the aggregation of vinyl molecules.


As I said, I haven't checked the numbers I was given myself, I was surprised by them but then the guy who gave them to me knows his cutting lathes, vinyl production and turntables and is full of facts and numbers... perhaps when he said molecule it was a misnomer for a larger particle?

In fact, if I'm being honest I couldn't swear in court if he said "molecule" or "particle", it was a very long day (and a very interesting one). The rest of his theory I'm pretty certain on.


Title: Re: George....what's the resolution of analog?
Post by: johnR on July 03, 2009, 07:04:56 am
Jay Kadis wrote on Thu, 02 July 2009 15:38


Given the dimensions of a stylus (microns), the molecular size of the particles themselves (nanometers) would not matter as much as the way the molecules pack together as there's a thousand-fold difference in size between the stylus and the surface molecular arrangement.  I doubt the stylus could follow individual molecules and would rather respond to the macro-level surface that would depend on the aggregation of vinyl molecules.

Excellent points, but bear in mind that a thousand-fold difference in linear movement is only 60dB.
Title: Re: George....what's the resolution of analog?
Post by: Jay Kadis on July 03, 2009, 04:11:05 pm
johnR wrote on Fri, 03 July 2009 04:04

Jay Kadis wrote on Thu, 02 July 2009 15:38


Given the dimensions of a stylus (microns), the molecular size of the particles themselves (nanometers) would not matter as much as the way the molecules pack together as there's a thousand-fold difference in size between the stylus and the surface molecular arrangement.  I doubt the stylus could follow individual molecules and would rather respond to the macro-level surface that would depend on the aggregation of vinyl molecules.

Excellent points, but bear in mind that a thousand-fold difference in linear movement is only 60dB.
Which is close to the dynamic range of the phonograph.
Title: Re: George....what's the resolution of analog?
Post by: KAyo on November 13, 2009, 02:35:50 am
Bob Olhsson wrote on Wed, 07 September 2005 20:19

I think Bob Katz treats this issue very well.

Since I can't rebuild most of the gear I have to use, I simply take the time to find the sweetest sounding gain structure for the system I'm using.


Brilliantly put!
That approach, is key to Analogue heaven. Dig deep to find the sweetest operations mode, and then fire all guns.

KAyo

Title: Re: George....what's the resolution of analog?
Post by: Dusk Bennett on November 18, 2009, 05:01:56 pm
sfdennis wrote on Fri, 14 May 2004 13:35

I'm surprised the thread got this far without anyone mentioning this:

Digital Word Length <=> Analog Noise Floor
Digital Sample Rate <=> Analog Bandwidth

So for example, in an ideal converter system at 96kHz would correspond with an analog bandwidth of 0-48kHz. A digital word length of 24 bits would correspond with an analog noise floor of about -132dBFS, notwithstanding dither.

-Dennis



Dennis,
I want to hit this point harder (and I may repost this separately since this is what I came here to ask). I got involved in an academic discussion today with a student regarding proper digital recording technique. He claims his professor (a Pohlmann student who's quite knowledgeable in her own right) stated that to obtain the highest resolution possible it is a MUST to record your sample as high up against 0dBfs as possible. (Which is a really bad idea IMHO). It's as if he's suggesting amplitude and "Word Length" are mutually exclusive (and you imply they are).

I have argued with the students here that there is no reason to "over record" in digital because the medium is much more forgiving than analog, and analog hardware cannot handle such hot levels coming out of digital converters. So I recommend that they print near 0VU (-20dBfs). There are many benefits to this in my mind (which I'll get into later), aside from the obvious.

So what is it? Is it really necessary in digital to print all the way up to 0dBfs to maximize your word length? Are amplitude and word length in digital truly related in that way? What do the facts say in digital theory on this?

The problem I have with recording so hot going into the box (especially if you end up interfacing with the outside analog world) is how much gain reduction one must apply to actually get your plug-ins and inserts to actually avoid distortion. Recording a guitar at -2dbfs leaves you no head room to compress and add eq after the fact without altering the "word length" of your inserts by reducing it's input to compensate for a very hot output. At that point aren't you just trading one set of problems for another?

I still believe (based on alot of practical experience) that there is no reason to print so fricking hot to digital. As long as you fall within the range of a typical VU meter your headroom in digital will allow for more than enough gain processing after the fact and not destroy the quality of the signal.

How would you respond to this?
Title: Re: George....what's the resolution of analog?
Post by: Tomas Danko on November 20, 2009, 06:33:19 am
Dusk Bennett wrote on Wed, 18 November 2009 22:01

sfdennis wrote on Fri, 14 May 2004 13:35

I'm surprised the thread got this far without anyone mentioning this:

Digital Word Length <=> Analog Noise Floor
Digital Sample Rate <=> Analog Bandwidth

So for example, in an ideal converter system at 96kHz would correspond with an analog bandwidth of 0-48kHz. A digital word length of 24 bits would correspond with an analog noise floor of about -132dBFS, notwithstanding dither.

-Dennis



Dennis,
I want to hit this point harder (and I may repost this separately since this is what I came here to ask). I got involved in an academic discussion today with a student regarding proper digital recording technique. He claims his professor (a Pohlmann student who's quite knowledgeable in her own right) stated that to obtain the highest resolution possible it is a MUST to record your sample as high up against 0dBfs as possible. (Which is a really bad idea IMHO). It's as if he's suggesting amplitude and "Word Length" are mutually exclusive (and you imply they are).

I have argued with the students here that there is no reason to "over record" in digital because the medium is much more forgiving than analog, and analog hardware cannot handle such hot levels coming out of digital converters. So I recommend that they print near 0VU (-20dBfs). There are many benefits to this in my mind (which I'll get into later), aside from the obvious.

So what is it? Is it really necessary in digital to print all the way up to 0dBfs to maximize your word length? Are amplitude and word length in digital truly related in that way? What do the facts say in digital theory on this?

The problem I have with recording so hot going into the box (especially if you end up interfacing with the outside analog world) is how much gain reduction one must apply to actually get your plug-ins and inserts to actually avoid distortion. Recording a guitar at -2dbfs leaves you no head room to compress and add eq after the fact without altering the "word length" of your inserts by reducing it's input to compensate for a very hot output. At that point aren't you just trading one set of problems for another?

I still believe (based on alot of practical experience) that there is no reason to print so fricking hot to digital. As long as you fall within the range of a typical VU meter your headroom in digital will allow for more than enough gain processing after the fact and not destroy the quality of the signal.

How would you respond to this?


In the theoretial world she would be correct.

But when looking at the implementations that we can use in reality, she would have to weigh the importance of getting "all the dynamic range" versus all the negative issues that arises when recording close to full scale. And there are many such negative issues, that will have a lot more negative impact on the audio compared to the initial concern.

A further study in the world of reality will also show that "full dynamic range" is somewhat of a can of worms considering the room noise floor, electronic noise floor of the signal chain including the A/D front end which could for instance indicate that only 80% or so of the theoretical "full dynamic range" is actually of practical interest.


It's not really part of the initial topic, but when also considering how much we futz with the dynamics (i.e. compression, limiting etc) to make an album of music it's even less important for the audio engineer to be able to capture the total full dynamic range.
Title: Re: George....what's the resolution of analog?
Post by: tamasdragon on December 12, 2009, 12:22:04 pm
Although I know it's a bit offtopic, but I'm really interested in it.
This is a question for all (George M., Bob O., Bob K., Paul F., etc.), do you think that today's digital audio is every bit as good as today's analog? Sonically and in every aspect?
Title: Re: George....what's the resolution of analog?
Post by: Geoff Emerick de Fake on December 12, 2009, 03:01:05 pm
Dusk Bennett wrote on Wed, 18 November 2009 16:01


So what is it? Is it really necessary in digital to print all the way up to 0dBfs to maximize your word length? Are amplitude and word length in digital truly related in that way? What do the facts say in digital theory on this?
It is a fact: 24 bit offer ca. 144dB dynamic range. Everytime you drop the level by 6dB, you loose 1 bit of resolution. Recording with a maximum INSTANTANEOUS level of -18dBfs uses only 21 of the available bits; the three MSB's will be constantly at 0.
Quote:


The problem I have with recording so hot going into the box (especially if you end up interfacing with the outside analog world) is how much gain reduction one must apply to actually get your plug-ins and inserts to actually avoid distortion. Recording a guitar at -2dbfs leaves you no head room to compress and add eq after the fact without altering the "word length" of your inserts by reducing it's input to compensate for a very hot output. At that point aren't you just trading one set of problems for another?
Different answers for outboard and for plug-ins. All reasonably designed plug-ins have built-in bit-depth (resolution) conversion that allows pre-attenuation, in an amount that will allow the most extreme processing to be handled nicely.
When using outboard, you have to consider the practicalities. If you use standard +4dBu equipment and your converter is set at +4dBu for -20dBfs, you should operate at -20dBfs, which leaves you with a real headroom of about 10db (depending on the type of meters), which is really one-and-a-half wasted bits. Different converters and different outboard gear woul give different numbers.
Quote:


I still believe (based on alot of practical experience) that there is no reason to print so fricking hot to digital.
"Hot" is an analog concept, tied to the progressive dirtying of signals when the level increases.  There is no such concept in the digital world. The only rule is to make sure that digital clipping is not reached, and that enough resolution is used for minimization of noise and quantizing distortion. Recording with 0.2 dB of headroom is not hot, it's just right. (I don't mean having a meter with the needle constantly at -0.2, I mean having the peak of the waveform reaching never higher than 0.2)
Quote:

 As long as you fall within the range of a typical VU meter your headroom in digital will allow for more than enough gain processing after the fact and not destroy the quality of the signal.

First of all, a VU meter is definitely not the right tool to monitor levels when tracking. The slow response leaves fast transients completely unnoticed; that's why you need to record conservatively low. Fortunately, the dynamic range of a 24bit system is so huge you can afford to loose 20dB (more than 3 bits) and get away with it. it doesn't mean it is good practice. The use of ultra-fast meters gives a much better control of recording level.
Title: Re: George....what's the resolution of analog?
Post by: Tomas Danko on December 13, 2009, 09:31:02 am
Geoff Emerick de Fake wrote on Sat, 12 December 2009 20:01

Dusk Bennett wrote on Wed, 18 November 2009 16:01


So what is it? Is it really necessary in digital to print all the way up to 0dBfs to maximize your word length? Are amplitude and word length in digital truly related in that way? What do the facts say in digital theory on this?
It is a fact: 24 bit offer ca. 144dB dynamic range. Everytime you drop the level by 6dB, you loose 1 bit of resolution. Recording with a maximum INSTANTANEOUS level of -18dBfs uses only 21 of the available bits; the three MSB's will be constantly at 0.



But when we step out of the world of theory and into the practical world of technical implementation and the actual digital tools that we have in order to record audio the 144 dB range does not really exist (i.e. several sources of noise). And when looking at the analog front end of most AD converters, they will start sounding bad a long time before reaching full scale.

We don't need more than 20-22 bits, and we don't need opamp distortion. Downstreams there is a lot said already about keeping levels far from full scale when mixing inside a DAW.

So all in all, advocating staying as close to full scale based on theory will only hurt actual recordings due to the way it's been practically implemented.
Title: Re: George....what's the resolution of analog?
Post by: compasspnt on December 13, 2009, 11:00:40 am
Tomas Danko wrote on Sun, 13 December 2009 09:31

So all in all, advocating staying as close to full scale based on theory will only hurt actual recordings due to the way it's been practically implemented.



Thank you Tomas.

I almost felt like giving up.
Title: Re: George....what's the resolution of analog?
Post by: Geoff Emerick de Fake on December 14, 2009, 11:12:25 am
Please remember, the question was: "Is it really necessary in digital to print all the way up to 0dBfs to maximize your word length? Are amplitude and word length in digital truly related in that way?". The answer to that simple question is simple.
Now, the poor implementation of the analogue counterparts may impose some limitations and operating workarounds, but the simple relation: "More level = more resolution" is a mathematical fact.
Fortunately, 24bit bit-depth offers so much headroom that it is possible to displace the operating range in an area where both analog and digital gear are happy.
Title: Re: George....what's the resolution of analog?
Post by: minister on December 23, 2009, 08:58:18 pm
Geoff Emerick de Fake wrote on Mon, 14 December 2009 10:12

Please remember, the question was: "Is it really necessary in digital to print all the way up to 0dBfs to maximize your word length? Are amplitude and word length in digital truly related in that way?". The answer to that simple question is simple.
Now, the poor implementation of the analogue counterparts may impose some limitations and operating workarounds, but the simple relation: "More level = more resolution" is a mathematical fact.
Fortunately, 24bit bit-depth offers so much headroom that it is possible to displace the operating range in an area where both analog and digital gear are happy.

This is the myth of Digital Audio that permeates the internet.  More level ≠ More Resolution. It is simply not a Mathematic Fact. The analogy to digital graphics and photography is, in fact, a DIS-analogy.  24 bit gives you more dynamic range above the Noise Floor.  It give you more "foot room", not "head room".

Recording close to 0dBFS invites not only inter-sample peak distortions, it is forcing your pre-DAW analog gear to operate beyond it's optimal range.  IOW, there is no way in which it is "good".

Title: Re: George....what's the resolution of analog?
Post by: Geoff Emerick de Fake on December 26, 2009, 07:28:36 pm
minister wrote on Wed, 23 December 2009 19:58

Geoff Emerick de Fake wrote on Mon, 14 December 2009 10:12

Please remember, the question was: "Is it really necessary in digital to print all the way up to 0dBfs to maximize your word length? Are amplitude and word length in digital truly related in that way?". The answer to that simple question is simple.
Now, the poor implementation of the analogue counterparts may impose some limitations and operating workarounds, but the simple relation: "More level = more resolution" is a mathematical fact.
Fortunately, 24bit bit-depth offers so much headroom that it is possible to displace the operating range in an area where both analog and digital gear are happy.

This is the myth of Digital Audio that permeates the internet.  More level ≠ More Resolution. It is simply not a Mathematic Fact.
Yes it is. For anyone with a notion of binary calculus, it is an evidence. This is a pure mathematical (digital) truth. Analogue has nothing to do in there.
Quote:

 It give you more "foot room", not "head room".
You are inventing strange new concepts that have no scientific existence. Dynamic range is the difference between OdBfs and noise floor. You can't do anything for optimising low levels, they're just as low as they are. The operating level is a compromise between all sorts of factors, one being avoidance of digital clipping and the others dictated by whatever compromises and optimisations have been done to the analog chain. But whatever you do, the higher the level, the higher the number of bits effectively used.
Quote:

 Recording close to 0dBFS invites not only inter-sample peak distortions, it is forcing your pre-DAW analog gear to operate beyond it's optimal range.
This is very often true, but inadequate implementation in the analog domain is not a reason to invalidate digital theory.
Title: Re: George....what's the resolution of analog?
Post by: Nick Sevilla on December 31, 2009, 01:04:53 pm
Gawd,

I'm unsubscribing from this awful mess...
Title: Re: George....what's the resolution of analog?
Post by: compasspnt on December 31, 2009, 01:21:04 pm
I am not the Moderator of this area, otherwise I might clean a bit of it up.

But I don't want to start a silly flame war, so I haven't responded forcefully as to my beliefs on this recent mess.
Title: Re: George....what's the resolution of analog?
Post by: minister on January 17, 2010, 12:54:27 am
Geoff Emerick de Fake wrote on Sat, 26 December 2009 18:28

minister wrote on Wed, 23 December 2009 19:58

Geoff Emerick de Fake wrote on Mon, 14 December 2009 10:12

Please remember, the question was: "Is it really necessary in digital to print all the way up to 0dBfs to maximize your word length? Are amplitude and word length in digital truly related in that way?". The answer to that simple question is simple.
Now, the poor implementation of the analogue counterparts may impose some limitations and operating workarounds, but the simple relation: "More level = more resolution" is a mathematical fact.
Fortunately, 24bit bit-depth offers so much headroom that it is possible to displace the operating range in an area where both analog and digital gear are happy.

This is the myth of Digital Audio that permeates the internet.  More level ≠ More Resolution. It is simply not a Mathematic Fact.
Yes it is. For anyone with a notion of binary calculus, it is an evidence. This is a pure mathematical (digital) truth. Analogue has nothing to do in there.
Quote:

 It give you more "foot room", not "head room".
You are inventing strange new concepts that have no scientific existence. Dynamic range is the difference between OdBfs and noise floor. You can't do anything for optimising low levels, they're just as low as they are. The operating level is a compromise between all sorts of factors, one being avoidance of digital clipping and the others dictated by whatever compromises and optimisations have been done to the analog chain. But whatever you do, the higher the level, the higher the number of bits effectively used.
Quote:

 Recording close to 0dBFS invites not only inter-sample peak distortions, it is forcing your pre-DAW analog gear to operate beyond it's optimal range.
This is very often true, but inadequate implementation in the analog domain is not a reason to invalidate digital theory.



http://recforums.prosoundweb.com/index.php/t/15038/0/

http://recforums.prosoundweb.com/index.php/mv/msg/4918/0/48/ 11603/

http://www.gearslutz.com/board/mastering-forum/69929-q-paul- frindle.html

http://www.amazon.com/Principles-Digital-Audio-Ken-Pohlmann/ dp/0071348190/ref=sr_1_2?ie=UTF8&s=books&qid=1263707 637&sr=1-2

Title: Re: George....what's the resolution of analog?
Post by: Geoff Emerick de Fake on January 18, 2010, 01:41:46 pm
Most of these threads are a collection of beliefs with not one line of scientific demonstration. It is quite interesting, however that Paul Frindle demonstrates that operating a TOO LOW level may introduce problems.
And again: Please remember, the question was: "Is it really necessary in digital to print all the way up to 0dBfs to maximize your word length? Are amplitude and word length in digital truly related in that way?".
There's only one answer to that: Yes
Because the question is exactly the same as: "Is it really necessary in analog to print all the way up to maximize S/N ratio? Are amplitude and S/N truly related in that way?". Again, yes.
I'm not saying that there won't be any problems, because there will be distortion, but the QUESTION doesn't mention distortion. To a unidimensional question, I bring a unidimensional answer. If distortion  had been mentioned in the question I would have said that S/N and THD are mutually exclusive. If the question was about quality, I would mention the compromise between wordlength and loss of headroom.
And I don't really need to read any "digital for dummies" book after 37 years of product development...
Title: Re: George....what's the resolution of analog?
Post by: compasspnt on January 18, 2010, 03:08:18 pm
I will inform George Massenburg to STOP his recording on analogue tape at significantly lowered levels.

He has been doing it wrong for 38 years.

But nothing will EVER make me go back to recording at "near red" levels on digital.

Maybe not scientific evidence, but my empirical observations are in NO DOUBT in my mind.

Way more than 38 years,

T
Title: Re: George....what's the resolution of analog?
Post by: Edvaard on January 18, 2010, 03:25:42 pm

If someone were about to go out driving for the first time and asked the simple question; "is it true that I need to have the accelerator all the way to the floor to reach top speed?" should I just give as answer a simple (and true) "yes" and leave it at that?


There is a series of sharp curves a half mile down the road, not to mention a speed limit whatever the road is like, and it being the first drive, no one knows how well the brakes work yet. But he didn't ask about any of that, so I'll only answer what he asked.




People here assumed by the very simplicity of the question that more information beyond the simple question might be warranted.

All people are trying to do is to say to an obvious newcomer "well, there's more to it than that."

Title: Re: George....what's the resolution of analog?
Post by: Geoff Emerick de Fake on January 18, 2010, 05:16:37 pm
compasspnt wrote on Mon, 18 January 2010 14:08

I will inform George Massenburg to STOP his recording on analogue tape at significantly lowered levels.
Did I say that? I've been pretty clear, running too hot generates distortion and running too low exacerbates noise. But again, I was answering someone who thought ther was a mystical relationship between level and resolution...
Title: Re: George....what's the resolution of analog?
Post by: Geoff Emerick de Fake on January 18, 2010, 05:29:05 pm
Edvaard wrote on Mon, 18 January 2010 14:25


If someone were about to go out driving for the first time and asked the simple question; "is it true that I need to have the accelerator all the way to the floor to reach top speed?" should I just give as answer a simple (and true) "yes" and leave it at that?
You're giving a misrepresentation. There was a affirmation that was similar to: "certainly, it cannot be that simple, more I push the pedal, faster the car goes, no, there must be something else?" And you cannot answer yes...
Quote:


There is a series of sharp curves a half mile down the road, not to mention a speed limit whatever the road is like, and it being the first drive, no one knows how well the brakes work yet. But he didn't ask about any of that, so I'll only answer what he asked.
He was not asking, he was rehashing some GS myth
Quote:


People here assumed by the very simplicity of the question that more information beyond the simple question might be warranted.

All people are trying to do is to say an obvious newcomer "well, there's more to it than that."
Does it really prevents anyone to tell the simple truth first? And there were about a hundred posts saying: don't go too fast!
Title: Re: George....what's the resolution of analog?
Post by: Edvaard on January 18, 2010, 06:34:45 pm

Geoff Emerick de Fake wrote on Mon, 18 January 2010 13:41

 
And again: Please remember, the question was: "Is it really necessary in digital to print all the way up to 0dBfs to maximize your word length? Are amplitude and word length in digital truly related in that way?".
There's only one answer to that: Yes
Because the question is exactly the same as: "Is it really necessary in analog to print all the way up to maximize S/N ratio? Are amplitude and S/N truly related in that way?". Again, yes.
I'm not saying that there won't be any problems, because there will be distortion, but the QUESTION doesn't mention distortion. To a unidimensional question, I bring a unidimensional answer. If distortion  had been mentioned in the question I would have said that S/N and THD are mutually exclusive. If the question was about quality, I would mention the compromise between wordlength and loss of headroom.




The driver only asked me how the accelerator worked; if he had asked me about the cliff just beyond the blind curve, I would have told him about it.

The 1 bit = 6dB info tells you as much about recording as knowing how the accelerator works tells you about driving. This site is about audio recording, and so necessarily about concerns of implementation of whatever technology. In any technology and for whatever purpose, the simple numbers are only a starting point.


I'm not meaning to question your intentions here, just saying that many in audio recording are well aware of the "a little learning can be a dangerous thing" phenomenon. The early digital audio especially is mostly unlistenable because people just went by the numbers, and then things improved noticeably when particulars of implementation and actual r/l limitations were better understood.



Title: Re: George....what's the resolution of analog?
Post by: Geoff Emerick de Fake on January 19, 2010, 02:57:57 am
I agree 100% with you. But when someone says: "It can't be true that more level means more significant bits", should we disagree or not? Just because the subject is complex, should we accept a misconception?
It is a matter of properly establishing where the flaws are.
Operating at reduced level is NOT the result of a digital limitation; it is a limitation due to the analog environment of conversion and the inadequacy of metering (which includes visual perception).
The goal is improving both the equipment and the process.
If we start with the notion that the problem lies in some inadequacy of the PCM representation, who will be motivated to improve the converter drivers and the meters?
Title: Re: George....what's the resolution of analog?
Post by: minister on January 25, 2010, 04:15:56 pm
Geoff Emerick de Fake wrote on Mon, 18 January 2010 12:41

And I don't really need to read any "digital for dummies" book after 37 years of product development...

Calling this book "digital for dummies" just reveals your arrogance which does not impress me in the least.  It is hardly a book for dummies. I suggest perusing it.



Title: Re: George....what's the resolution of analog?
Post by: Geoff Emerick de Fake on January 26, 2010, 06:16:55 pm
minister wrote on Mon, 25 January 2010 15:15


Calling this book "digital for dummies" just reveals your arrogance which does not impress me in the least.
I'm not impressed with yours either. Your "recommandation" to read these posts and books was quite rude. Like recommanding Popular Electronics to Dan Lavry or George Massenburg...
Quote:

 It is hardly a book for dummies. I suggest perusing it.
I have more than perused it. I have the first edition of it, and read it. It's an excellent scientific popularization, where all subjects are covered not in great depth. It's not a book that can be used for designing products.
But it is largely sufficient to answer the question: Does more level means more significant bits?