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[Andy Simpson]

Brian Roth wrote on Tue, 12 July 2005 06:32

andy_simpson wrote on Mon, 11 July 2005 11:20 Brian Roth wrote on Mon, 11 July 2005 10:23 The test chain was ten opamps in a sequence, set as inverters running 20 dB gain with a 20 dB "pad" between each. Looks like it's time to do that test gaian! Bri Cool. So what was your conclusion at the time?! Andy Time frame was probably 1977 when the TDA1034 (soon thereafter known as the NE5534) was introduced.  The listening system was far from "high def" as we know it today (JBL studio monitor driven by that large Yamaha power amp which was popular at the time...model number forgotten).  I had been using LF356 opamps in custom equipment, and you could hear 10 of them in a string vs. a straight wire.  *Within the limitations of the monitoring chain*, 5534's added practically nothing compared to the wire bypass.  For grins, LM-301 really sounded bad. Nearly 30 years have passed, all signal chains have improved, so that makes me want to repeat similar tests, especially since it never dawned on me in 1977 to do a null test. Bri

Cool.

Cynical question no. 1, what was the source material? (Was it something with amazing depth/image/etc?).
Cynical question no. 2, was the monitoring system capable of delivering a 'fuck, the band is in the room with me' type of compelling sound?
I guess the null test would have been utterly definative either way, regardless of the source material and monitors.

Please do repeat the test!!! The results of a null test would tell us alot.

Andy

[Brian Roth]

Andy, the tests were pretty primitive by today's standards.  Mono only (it was enough of a PITA to cobble 10 opamps in series with pads!).  Source material was a hodgepodge as I recall.  Probably some 15 IPS 2T masters and things like Dark Side or Crime of the Century from LP...probably some Steely Dan LP sources.

At the time, JBL monitors were the "happening thing", but I sure don't recall which model.

I was 23 years old in 1977, and struggling to sort out many audio design issues.  At that time, the " 'golden ears' had it out" for things like Neve desks with all the transformers in the path.  I was trying to get a grip on what seemed to be transparent and what was not.

With the then-available test gear, the limitations of the 356 and 301 opamps in a string could be detected.  The 5534 chain measured well, IIRC.

Now, my next trick is figuring out the best parts for a null-er-ator <g>.  I'm leaning towards the LM318 since I have some sitting in a parts drawer.

Bri

[Andy Simpson]

maxdimario wrote on Mon, 11 July 2005 17:57

Quote: it takes a lot to kill music, and, if it's alive (skip james, robert johnson etc), the sonics will not stand in its way (up to a point) Intresting enough, I was talking to someone last night who had a western electric horn with a big woofer in his mono HI-FI 40+ years ago and he was talking about realism etc. being there.. he also mentioned audiophile 78 records which were pressed on red vinyl and how much superior they were realism-wise to anything he'd heard since.

Interesting that the horn often gets mentionned when people are describing super 'in the room with me' audio experiences.

Yesterday I was doing a rough mix on location in a rehearsal space I'd been recording a band in. Anyway, for fun I ran up my monitors to 'performance' level, pressed play and ran to the safety of the next room.
Listening from the other room, the illusion of a band in the next room was so convincing, I swear I could easily fool somebody into thinking there really was a band in there. In particular, the ride & cymbals, the general rhythm section was so big, clear and real sounding.
That was on my previously mentionned srm450 mackies, horn loaded.
I am loving these monitors more every day!

Andy

[leban (giancarlo)]

dcollins wrote on Sun, 10 July 2005 23:55

maxdimario wrote on Sun, 10 July 2005 14:28 Distortion or deformation of the waveform is the principal concern to be dealt with. But only you can detect this distortion?  No equipment, regardless of sophistication, will show it? Quote: Phase shift does not create too many problems, but phase distortion does. This one could do with a little fleshing out.  When does "shift" become "distortion?  Is it the rate of change?  A certain amount of degrees?  When the high-end is delayed more than the bottom?   All my EQ's change the wave-shape, that's what they do. Quote: Digital distortion is the worst kind of distortion, and I suspect that there is a lot of phase distortion (not shift) in digital encoding and decoding, much more than analog. Factual distortion is actually the worst kind....... DC

My simple suggestion, not perfect because the capture done via digital converters (ic based!):
All he is measurable. The impulse response is defined as the response of a system to a  input. This is maths.
What you need for a digital measurament is
1) the best possible A/D e D/A converters pair in the market.
2) the same A/D e D/A configuration for a direct A/B comparison.
Digital converters can add a bit distortion etc but what you can check is the 'difference' between the two results (for example if in both you have phase shift in 5Khz range you can guess it is for DACs)
Impulse response is an audio file, you can check phase distortion/shift, distortion, linearity simply analyzing with any kind of computer audio editor.

In synthesis
a) a test signal (for example a 24 seconds test signal) played in your gear with your optimum A/D converters
b) you capture with the best possible D/A converters
c) you calculate deconvolution (a math processing, voxengo deconvelver can do it)
d) you have the response of your system.

I'm an electrical engeneer and i see the solution from my point of view...

[zmix]

dayvel wrote on Mon, 11 July 2005 23:43

I think you could grow a damn fine garden in this thread.

This is Plato's "Cave"... nothing will grow in here.

[compasspnt]

What's that shadow on the wall?

[Johnny B]

Will the bearer of truth again be killed, or will the "Analogue vs. Digital vs. Tubes vs. Discrete Transistors vs. IC's vs. Tranformers vs. Tranformerless vs. 192Khz and Greater/Newer/More Advanced SRC's Debate" simply continue to rage on with people still asking those nasty probing questions like "Yeah, but why does it still sound like ass?"

Will newer/better test suites provide more clues, or, will the mystery/saga keep playing in serialised episodes with more juicy tid-bits revealed each week?...only someone with the wisdom of a Socrates knows.

And when Socrates knows something, he can teach it to Plato who can then pass the lesson on to us mortals.



 

[zmix]

Plato and Socrates were human philosophers, and certainly mortals.

The story of Plato's Cave is about people so obsessed by an artifact ( a shadow cast upon a wall) that they think this artifact is actually the thing itself. They argue about the shadows although none of them have any knowledge of, or have ever seen the thing that is causing the shadows to appear.

[Johnny B]

Perhaps one of the things that is being underscored here is all the anomalies introduced by the IC chain, here is but one example of the problems that must be overcome:

  http://www.analog.com/UploadedFiles/REDESIGN_IC_Anomalies/19 5504460ts101_anomaly52605.pdf

Of course there are even more anomalies out there for other IC's.

For example, see:

http://www.analog.com/processors/technicalSupport/hardwareAn omalies.html


Certainly no one could argue that anomalies don't exist for the tube, transistor, discrete, or analogue systems out there,  just that we know the truth that they are there, they have been revealed, and they are all very different from one another.

In this sense, we have come out of the Cave, albeit, only a little.

[zmix]

Johnny, these are lists of DSP hardware and coding anomalies. You may as well post the known bug lists for OSX here...  

                                                                   :

[Johnny B]

Yeah, I know..it was only a quick and dirty response and merely provided as an example of the strange behavior or "anomalies" one can find with IC's.

Last time I checked, DSP were IC's..I think that's still true...in fact...DSP chips seem to be all over the place in the digital domain.

BTW, I'm not saying the other competing technologies do not have their own anomalies, just showing that IC's have them.

Whether a more particularised IC anomaly is more at fault or more to blame for killing the music is another question altogether.

The point I was attempting to make is that IC's, in general, *have* "anomalies."

[zmix]

don't we all.......

[Johnny B]

I can't speak for others, but the mean lady who lives with me, beats me with her closed fists and gives me black eyes and fat lips says I have a lot of problems. To be honest, I think she's my biggest problem. She's a huge anomaly in my life. I think I'll trade her in on three twenty-year-olds...that'll fix her.

I'll say this for her tho', she does have a good ear and can hear crap in bad IC circuits.

[JGreenslade]

DC wrote:

Quote:

Douglas Self is the worst possible example to bring into this thread. He is the ultimate objectiveist, and believes in measurement. His books are full of AP plots and discussions of how to lower distortions in every stage....

Sorry about that... Self is a real party pooper...just imagine what the discussion groups would be like if we adhered to Self's protocol...

BTW, Self is not the only objectivist that advocates Class B operation in power amps - funny that... He must be using a *fair* amount of forward bias to get away from the worst regions of switching distortion, but on the whole I get the impression that many of his ilk tend to view pure Class A in power amps as a scenario where the cure for the problem (i.e. efficiency well below 20% and excess heat build-up) is worst than the symptoms...

I haven't taken the time to study Self's power amp designs - is he an advocate of feed-forward error correction? I believe a certain well-known Canadian amp OEM use FFEC, and consequently performance on paper looks good, without upsetting "Friends of the Earth".

Justin

edit: Self on Power amps

[maxim]

just to take this thread for another spin, the real enemy is not is the IC's, and not even the drum loop

imo, the most heinous crimes against music have been commited by people who believe that human beings have an innate ability to play bongos