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And this is why people still use tube amplifiers with design from 70s, just with modern high quality power supplies and EMF practices, right? I don't

And this is why people still use tube amplifiers with design from 70s, just with modern high quality power supplies and EMF practices, right? I don't see how that follows from anything I've said. What I said was that the field of audio engineering is 100+ years old and we know what sounds good. What I did not say is that we've ceased making progress. (A lot of the progress we've made has been negative, IMO, sacrificing sound quality for miniaturization, but that a whole other tangent) In a nutshell, "what sounds good" to the most people most of the time is accurate signal reproduction, plus some tweaking of the output to conform to a house curve like the Harman target response. There is some room for personal preference, of course. And of course some kinds of distortion can sound pleasing such as even order harmonic distortion. If you have not done that, you are a number chaser not an objectivist. A Pythagorean. This is hogwash of the highest degree on a couple of different levels. It's like saying you can't believe the moon exists unless you've been there. I've read the controlled research by Toole et al, and while he could certainly be lying, I haven't seen a credible refutation. Haven't ever seen an electron with my own eyes either but there's some pretty compelling research proving they exist. We don't know what to measure and how, besides a few total fail checks. What a remarkable claim. Let me turn this around. How do you feel it's possible that we're 100+ years and many generations of audio engineers into this multi-trillion dollar industry and we still don't know what sounds good? According to you we literally haven't even figured out how to measure this stuff? What a laugh. That would be an absolutely remarkable state of affairs. How about photographs and video displays? Same thing? We're just spitballin' it there, too? Got a bunch of artistes in the TV factory just sort of tweaking each set till it looks good enough?

AstralStorm 4y ago
The existence of the moon is not a metric someone invented. It can be detected by many (at least 5 available to general populace) means, its shape and features too. Stop making bad analogies and howaboutism. Our "distortion metrics" are barely validated garbage that has not been corrected since 60s. (Including THX standard which uses them, a pretty funny joke. It does better at room and speakers.) Hence, they are only useful as a check not a rating. We do know what sounds good, obviously it is an application of a bass boost knob. /s What's under the question is what sounds accurate (or accurate enough) and high fidelity. And the metrics we have typically do not answer it in the positive, only in a weak negative. People designing amplifiers typically do not chase these numbers too hard either, since that ends subjectively audibly poorly. We do not happen to have perfect amplifiers, it turns out. The metrics are not psychoacoustic for one, nor have been correctly validated. Better ones have been proposed but not applied. There are some definitive statements like "distortion 80 dB lower than signal cannot be heard in headphones" but there's no validation of it. (Plus it seems suspicious compared to what we know about psychoacoustic masking and absolute thresholds of hearing. Plus time domain behavior might be audible too in some cases, we just don't have an audio metric for that.) Some people have taken to plotting harmonic distortion graphs for multiple orders separately already, but it is way rare and still hard to interpret and it still does not differentiate audibly different (and differently annoying) kinds of distortion.
- JohnBooty 4y ago
  My goodness. How spectacular of you to claim this area hasn't been researched! There has been massive amounts of research on the audibility of various aspects of audio reproduction. Literally tens of thousands if not hundreds of thousands of papers. For starters: https://www.google.com/search?q=audibility+site%3Aaes.org https://www.google.com/search?q=audibility+site%3Aaes.org https://www.google.com/search?q=preference+site%3Aaes.org https://www.google.com/search?q=preference+site%3Aaes.org This discussion is over.
  - AstralStorm 4y ago
    Oh come on. I namedropped AES papers almost by name. (The response to it in particular.) And definitely by name in another post. Nobody uses that metric, because industry Does. Not. Care. It's also still an integral unvalidated metric - it has not been subjected to listening tests to evaluate the thresholds nor figure out its limitations. If I missed a paper, point it out in a less lazy way. The last one that did something was in 1984 by Edward Cherry with a funky tunable distortion generating ampliifer. Even that was not a panel evaluation. There are more or less two benchmark quality amplifiers out there (I know of, and happen to be Benchmark) done by chasing the numbers, oscilloscope traces (because metrics are insufficient), a lot of modern error correction maths (90s era) in addition to validation by ear. I gave up trying to decode their feedforward plus feedback topology in detail, it's hard and not the usual example. These cost serious money. Trades some power efficiency too. One could use one of these to evaluate any and new metrics more easily, but nobody does that.

AstralStorm 4y ago

The existence of the moon is not a metric someone invented. It can be detected by many (at least 5 available to general populace) means, its shape and features too. Stop making bad analogies and howaboutism. Our "distortion metrics" are barely validated garbage that has not been corrected since 60s. (Including THX standard which uses them, a pretty funny joke. It does better at room and speakers.) Hence, they are only useful as a check not a rating. We do know what sounds good, obviously it is an application of a bass boost knob. /s What's under the question is what sounds accurate (or accurate enough) and high fidelity. And the metrics we have typically do not answer it in the positive, only in a weak negative. People designing amplifiers typically do not chase these numbers too hard either, since that ends subjectively audibly poorly. We do not happen to have perfect amplifiers, it turns out. The metrics are not psychoacoustic for one, nor have been correctly validated. Better ones have been proposed but not applied. There are some definitive statements like "distortion 80 dB lower than signal cannot be heard in headphones" but there's no validation of it. (Plus it seems suspicious compared to what we know about psychoacoustic masking and absolute thresholds of hearing. Plus time domain behavior might be audible too in some cases, we just don't have an audio metric for that.) Some people have taken to plotting harmonic distortion graphs for multiple orders separately already, but it is way rare and still hard to interpret and it still does not differentiate audibly different (and differently annoying) kinds of distortion.

JohnBooty 4y ago
My goodness. How spectacular of you to claim this area hasn't been researched! There has been massive amounts of research on the audibility of various aspects of audio reproduction. Literally tens of thousands if not hundreds of thousands of papers. For starters: https://www.google.com/search?q=audibility+site%3Aaes.org https://www.google.com/search?q=audibility+site%3Aaes.org https://www.google.com/search?q=preference+site%3Aaes.org https://www.google.com/search?q=preference+site%3Aaes.org This discussion is over.
- AstralStorm 4y ago
  Oh come on. I namedropped AES papers almost by name. (The response to it in particular.) And definitely by name in another post. Nobody uses that metric, because industry Does. Not. Care. It's also still an integral unvalidated metric - it has not been subjected to listening tests to evaluate the thresholds nor figure out its limitations. If I missed a paper, point it out in a less lazy way. The last one that did something was in 1984 by Edward Cherry with a funky tunable distortion generating ampliifer. Even that was not a panel evaluation. There are more or less two benchmark quality amplifiers out there (I know of, and happen to be Benchmark) done by chasing the numbers, oscilloscope traces (because metrics are insufficient), a lot of modern error correction maths (90s era) in addition to validation by ear. I gave up trying to decode their feedforward plus feedback topology in detail, it's hard and not the usual example. These cost serious money. Trades some power efficiency too. One could use one of these to evaluate any and new metrics more easily, but nobody does that.