Debate isn't going to resolve the dispute. The mistaken understanding needs to be replaced by a more proper explanation. It could be true in some cases that a faster amp sounds better than a slow one, for reasons I explained in Bob Cordell's thread.
There may be another factor at work here too: There is something called, "The Focusing Illusion." https://www.princeton.edu/~ceps/workingpapers/125krueger.pdf
We have someone who is deeply focused on a particular yet mistaken explanation for why a faster amplifier sounds better than a slower one. The focusing, the thinking about it, the trying to find a way to convince others of its supposed correctness all serve to make it seem much more of an important realization than it actually is.
To hammer the point home once more, debate that first cycle distortion, etc., can't be possibly be a correct explanation is far off the mark since that does not resolve the need for a better and more accurate explanation.
There may be another factor at work here too: There is something called, "The Focusing Illusion." https://www.princeton.edu/~ceps/workingpapers/125krueger.pdf
We have someone who is deeply focused on a particular yet mistaken explanation for why a faster amplifier sounds better than a slower one. The focusing, the thinking about it, the trying to find a way to convince others of its supposed correctness all serve to make it seem much more of an important realization than it actually is.
To hammer the point home once more, debate that first cycle distortion, etc., can't be possibly be a correct explanation is far off the mark since that does not resolve the need for a better and more accurate explanation.
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Jan,
A proper listening test would be great. However, its not something EEs are trained in or typically have expertise at. How many here have studied the books and papers on the subject of sensory testing that were recommended by Jakob2? My guess would be: Nobody.
Also, who that has expertise is located close enough to the amplifier in question to organize and supervise the sensory testing?
A proper listening test would be great. However, its not something EEs are trained in or typically have expertise at. How many here have studied the books and papers on the subject of sensory testing that were recommended by Jakob2? My guess would be: Nobody.
Also, who that has expertise is located close enough to the amplifier in question to organize and supervise the sensory testing?
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I know, but that also means that reports that an amp sounds better than another by someone who holds wrong views are anyway worthless.
Jan
Hmmm. Seems to me someone could be good at listening and much less good at theorizing. Don't know why the two abilities or skills would necessarily have to be correlated.
What does make me suspicious that there is likely something to the fast amplifier thing is that lots of people from different cultures and different places in the world seem to report similar subjective listening experiences. I don't think it can so easily be attributed entirely to humans and not at all to amplifiers. Nothing new of course, plain old physics at work in real world conditions, would be my guess.
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@petr_2009, it's interesting to compare various compensation methods, assuming appropriate leveling has been done, so we have apple-to-apple comparison.
Performance of any compensation method certainly depends on chosen C and R values. In your analysis which criteria have you used for dimensioning of compensation components to ensure like for like comparison? AFAIS they have different BW, phase margin, etc.
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The optimization criteria are as follows:
1. Get a phase margin as close to 60 degrees as possible;
2. Get as large a loop gain as possible at the upper operating frequency of 20 kHz;
3. Get as little Group Delay Time as possible
At the very beginning, I gave the VAS circuit without correction elements. If you manage to get the best results without changing the operating modes of the transistors, then please share your result.
When something seems certain way to you, the first order of business would be to verify it. If not, it's just a thought and guesswork as shown below.
I'd love to see a credible theory why faster is better. IIRC when we looked for any examples in real music of a transient that would trouble even the lowest of slew rate amplifiers none was found. So if all these people 'hear' something better with faster amplifiers what is going on other than delusion?
Transients can be generated by nonlinearity in the circuit, e.g. crossover distorsion, class D, etc. Speed FB amp copes better with the artefacts.