Slightly OT:
Just found out that Peter Aczel who founded and ran The Audio Critic for many decades recently passed away. Starting out as a hard-core subjectivist, he soon saw the light and became a champion for scientific explanations, facts & figures and controlled listening tests (closed-loop listening as he called it).
His 1995 AES paper is still very much relevant.
(To my consternation it even has a reference to one of my designs of way back when ;-).
Jan
Just found out that Peter Aczel who founded and ran The Audio Critic for many decades recently passed away. Starting out as a hard-core subjectivist, he soon saw the light and became a champion for scientific explanations, facts & figures and controlled listening tests (closed-loop listening as he called it).
His 1995 AES paper is still very much relevant.
(To my consternation it even has a reference to one of my designs of way back when ;-).
Jan
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I never found much good in Peter Aczel's 'The Audio Critic' in its later incarnation. It badmouthed just about everybody I knew in audio, and I came under fire sometimes as well. They weren't very professional about it either. But in the early years, the late 1970's, John Meyer and I actually measured some amplifiers (not ours) and published them in his publication to show differences in TIM between different brands. I got a lot of flack from Audio Research when I showed that their solid state amp had TIM. Of course, today, that solid state amp is virtually forgotten, although their tube stuff is still highly regarded.
Yeah, Peter's style could grate a bit, but the guy was clearly just so done with all the nonsense. Most of the time I could understand his frustration.
Farewell, Mr. Aczel.
Farewell, Mr. Aczel.
Sometimes you simply don't have to say anything and let comments speak for themselves. ... Okay, I have to say something.
John, this doesn't surprise me at all considering where you are coming from and where he was coming from. 😀
-Chris
Sure, to the most of us the nonsense factor in high-end audio is going/has gone much too far.
My objection to Hifi Critic is he goes too far in the cynical direction.....very much like Ethan Whiner.
So many things affect/effect audio systems....the standard test bench does not say all.
Dan.
The standard test bench can't say all. It can call B.S. on obvious problems. To really tell you need slightly better equipment and add a few pieces of real expensive stuff. Then you can see a great deal more.
-Chris
-Chris
Oh, so that is how you are seeing things! 🙂
(I try not to miss such an obvious straight line.)
When I first met Peter Aczel back in the late 70's, he seemed to be an OK reviewer. He appreciated John Meyer's and my measurements of TIM that he published and we continued to have a pretty good distant relationship, occasionally by phone. As I recall, his early mags had a bit of humor in them.
Later, he apparently got into trouble with his subscribers, partially because he gave a good review to a speaker that he personally designed, without disclosing it, and then not continuing with his publication, while apparently having a number of paid subscribers.
Later, perhaps a few years, he restarted the magazine with this 'double blind bent' and a cynical attitude toward most other reviewers and many audio manufacturers. He was not as bad as his associate, a PhD who thought a great deal of himself, and could be extremely critical and insulting, including insulting me on occasion. He was far worse than Peter Aczel, but Peter did not attempt to keep him constrained to a professional level of discourse, so I became disappointed in Peter for that as well.
I remember one time when one of my Parasound power amps was tested and the PhD insisted that it could not possibly meet its measurement specs. But it did! The reason was is that a previous design had technical error which DID make more distortion than I designed into the amp, and Mr. PhD gave me lots of heat for it, but he did not bother to tell me personally, he just told the world what a crummy designer I was, because I removed an IC and put in, instead, a Class A dual jfet follower.
Unfortunately, I had designed and spec'd in writing for the builders to use a Toshiba 2sk170V (hi Idss) fet (pair) and the builder ignored my written instructions and instead used 2sk170GR jfets (low Idss). I had biased the design with 47 ohm resistors, when 10 ohms would have been much more appropriate. The added resistance turned off the follower so that it went nonlinear prematurely. I fixed the problem immediately, when I learned about it, but the damage was done, and I would have appreciated some feedback from the magazine before them attempting to defame me for this 'oversight'. That is the sort of thing that made the publication 'cynical' rather than balanced.
Later, he apparently got into trouble with his subscribers, partially because he gave a good review to a speaker that he personally designed, without disclosing it, and then not continuing with his publication, while apparently having a number of paid subscribers.
Later, perhaps a few years, he restarted the magazine with this 'double blind bent' and a cynical attitude toward most other reviewers and many audio manufacturers. He was not as bad as his associate, a PhD who thought a great deal of himself, and could be extremely critical and insulting, including insulting me on occasion. He was far worse than Peter Aczel, but Peter did not attempt to keep him constrained to a professional level of discourse, so I became disappointed in Peter for that as well.
I remember one time when one of my Parasound power amps was tested and the PhD insisted that it could not possibly meet its measurement specs. But it did! The reason was is that a previous design had technical error which DID make more distortion than I designed into the amp, and Mr. PhD gave me lots of heat for it, but he did not bother to tell me personally, he just told the world what a crummy designer I was, because I removed an IC and put in, instead, a Class A dual jfet follower.
Unfortunately, I had designed and spec'd in writing for the builders to use a Toshiba 2sk170V (hi Idss) fet (pair) and the builder ignored my written instructions and instead used 2sk170GR jfets (low Idss). I had biased the design with 47 ohm resistors, when 10 ohms would have been much more appropriate. The added resistance turned off the follower so that it went nonlinear prematurely. I fixed the problem immediately, when I learned about it, but the damage was done, and I would have appreciated some feedback from the magazine before them attempting to defame me for this 'oversight'. That is the sort of thing that made the publication 'cynical' rather than balanced.
Before I read about Aczel I never heard the expression 'open loop listening' or 'closed loop listening'. It's easy (I believe) to understand what it means. It's all about checks and balances to keep you honest.
Fragment from his Conclusions of the earlier linked paper makes clear how he saw it. He must have agreed with Gordon Holt all the way.
3 CONCLUSION
The examination of the topologies of audio equipment said to "sound good" has shown little commonality in the designs. Some designs use no feedback, others a small amount, and yet others a large amount at low frequencies. Some designers include the output stage in the feedback loop; others do not. Some designers will use no capacitors in the signal path; others will use only expensive film caps, while still others use less expensive electrolytics. Some designers will use complex power-supply regulators, while others will use no regulation at all in power amplifiers. Some designers will work mostly with FETs; others use only bipolar devices. Some designers use fully complementary circuits, while others use only single-ended circuits. Some designers use ICs in the signal path or for voltage regulation; others will use only discrete designs. Some designers may even mix design styles within a given unit.
The random nature of the designs strongly suggests that no "X factor" parameter is being optimized. Instead, we can assume that the designer, using open-loop listening tests, has convinced himself that the changes he is making to the circuitry are affecting the sound. In this process---design, listen open-loop, design--- the circuit designer has no checks and balances to guide him in his work. Open-loop listening is to a very great extent subject to the biases of the listener, and a designer wanting to prove that his new idea is better-sounding is clearly biased.
Closed-loop listening tests would show if a change were truly happening when a circuit change was implemented, but designers are unhappy when a new circuit idea is shown by such tests to be of no consequence. They thus try to dismiss the controlled test results, instead of facing the reality that electronics exhibiting proper measurements are sonically transparent. This can often work in reverse. A designer might not use in his circuit an expensive component that would result in a measurable change in the device's performance because he has convinced himself through open-loop listening tests that the better component produces no sonic change. That is probably the reason why a lot of very expensive high-end equipment uses inexpensive D/A converters or digital interpolation filters. Considerably less expensive mainstream components, often said to sound less good in open-loop listening tests, use much better-performing parts.
Fragment from his Conclusions of the earlier linked paper makes clear how he saw it. He must have agreed with Gordon Holt all the way.
3 CONCLUSION
The examination of the topologies of audio equipment said to "sound good" has shown little commonality in the designs. Some designs use no feedback, others a small amount, and yet others a large amount at low frequencies. Some designers include the output stage in the feedback loop; others do not. Some designers will use no capacitors in the signal path; others will use only expensive film caps, while still others use less expensive electrolytics. Some designers will use complex power-supply regulators, while others will use no regulation at all in power amplifiers. Some designers will work mostly with FETs; others use only bipolar devices. Some designers use fully complementary circuits, while others use only single-ended circuits. Some designers use ICs in the signal path or for voltage regulation; others will use only discrete designs. Some designers may even mix design styles within a given unit.
The random nature of the designs strongly suggests that no "X factor" parameter is being optimized. Instead, we can assume that the designer, using open-loop listening tests, has convinced himself that the changes he is making to the circuitry are affecting the sound. In this process---design, listen open-loop, design--- the circuit designer has no checks and balances to guide him in his work. Open-loop listening is to a very great extent subject to the biases of the listener, and a designer wanting to prove that his new idea is better-sounding is clearly biased.
Closed-loop listening tests would show if a change were truly happening when a circuit change was implemented, but designers are unhappy when a new circuit idea is shown by such tests to be of no consequence. They thus try to dismiss the controlled test results, instead of facing the reality that electronics exhibiting proper measurements are sonically transparent. This can often work in reverse. A designer might not use in his circuit an expensive component that would result in a measurable change in the device's performance because he has convinced himself through open-loop listening tests that the better component produces no sonic change. That is probably the reason why a lot of very expensive high-end equipment uses inexpensive D/A converters or digital interpolation filters. Considerably less expensive mainstream components, often said to sound less good in open-loop listening tests, use much better-performing parts.
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Earl Geddes said we know pretty accurately what about 95% of the population can hear. He also seemed to be saying nobody has seriously tried to evaluate the top 5% because of (1) expense, and (2) nobody really cares.
Ethan Winer, on the other hand, sometimes makes sweeping statements such as that NOBODY can hear CD dither. Also, when I read Ethan describe some of his experimental methods for human subject research, it appears to be of less than professional quality. Those things being said, Ethan often seems to be a reasonable guy. But, other times, not so much.
Did you miss my aim? I was inquiring about if what you saw was real. After all would anyone sane really spend time on this thread? 😉
I find the logic of Article and Conclusions pretty sharp, genius, commending.
But I also complain: Aczel did not look for "X^2-Factor"!
Indeed, "that" is what designers are trying us to convey he missed, sickening the world by delivering only(sic!) his appreciation for their high engineering skills and humble genius merits. This is not cynism. My. opinion.
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