R/E/P Community

Please login or register.

Login with username, password and session length
Advanced search  

Pages: 1 ... 16 17 [18] 19 20 ... 23   Go Down

Author Topic: George....what's the resolution of analog?  (Read 83319 times)

danlavry

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 997
Re: George....what's the resolution of analog?
« Reply #255 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

Logged

Johnny B

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1134
Re: George....what's the resolution of analog?
« Reply #256 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.

   
Logged
"As far as the laws of mathematics refer to reality,
they are not certain; as far as they are certain,
they do not refer to reality."
---Albert Einstein---

I'm also uncertain about everything.

danlavry

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 997
Re: George....what's the resolution of analog?
« Reply #257 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





Logged

Thomas Lester

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 677
Re: George....what's the resolution of analog?
« Reply #258 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

ted nightshade

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1272
Re: George....what's the resolution of analog?
« Reply #259 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!
Logged
Ted Nightshade aka Cowan

There's a sex industry too.
Or maybe you prefer home cookin'?

bluespark

  • Newbie
  • *
  • Offline Offline
  • Posts: 10
Re: George....what's the resolution of analog?
« Reply #260 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
Logged
Daniel P Gardopée
Blue Spark

Sjoko

  • Newbie
  • *
  • Offline Offline
  • Posts: 26
Re: George....what's the resolution of analog?
« Reply #261 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.
Logged
Sjoerd (Sjoko) Koppert
http://www.tantrumrecords.org

CCC

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 623
Re: George....what's the resolution of analog?
« Reply #262 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!
Logged
 

Sjoko

  • Newbie
  • *
  • Offline Offline
  • Posts: 26
Re: George....what's the resolution of analog?
« Reply #263 on: September 04, 2005, 02:35:27 pm »

time for a 28 bitproof drink Cool
Logged
Sjoerd (Sjoko) Koppert
http://www.tantrumrecords.org

Ronny

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 2739
Re: George....what's the resolution of analog?
« Reply #264 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.
Logged
------Ronny Morris - Digitak Mastering------
---------http://digitakmastering.com---------
----------Powered By Experience-------------
-------------Driven To Perfection---------------

Sjoko

  • Newbie
  • *
  • Offline Offline
  • Posts: 26
Re: George....what's the resolution of analog?
« Reply #265 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

Logged
Sjoerd (Sjoko) Koppert
http://www.tantrumrecords.org

Ronny

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 2739
Re: George....what's the resolution of analog?
« Reply #266 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.
Logged
------Ronny Morris - Digitak Mastering------
---------http://digitakmastering.com---------
----------Powered By Experience-------------
-------------Driven To Perfection---------------

Ronny

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 2739
Re: George....what's the resolution of analog?
« Reply #267 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.
Logged
------Ronny Morris - Digitak Mastering------
---------http://digitakmastering.com---------
----------Powered By Experience-------------
-------------Driven To Perfection---------------

dcollins

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 2815
Re: George....what's the resolution of analog?
« Reply #268 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

maxdimario

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 3811
Re: George....what's the resolution of analog?
« Reply #269 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?
Logged
Pages: 1 ... 16 17 [18] 19 20 ... 23   Go Up