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Re: Thanks for the note

" I know that nonlinear distortion in speakers is irrelavent"
Why is that? Is it because most of the distortion is largely 2nd or 3rd order harmonics? My guess is that most processes don't produce much in the way of high order harmonics like you find in electronics.


"It was only after I had time to ponder the implications of what we had learned that I realized where a tube amp might sound better than a SS amp. It's the feedback that is the problem not whether its sand or vacuum"

Hmmm...its interesting that as a result of the implications from using your metric that you realized that a tube amp might sound better than a typical SS amp but didn't your ears also tell you this?

BTW. I tend to agree that feedback is the problem because I own and have heard some hybrid amps with no feedback that have truly excellent sound quality (far better than most pure tube amps in fact that I have heard). One of the ones that I know to have no feedback scored very well using the Shorter metric and it sounds superb. I have also heard pure tube amps with limited feedback that sounded extremely good as well (I own an OTL amp that is in this category).

Interestingly, the hybrids and the OTL don't sound so different as topologically they are very similar. One thing I could imagine is that all amps that score very well or very poorly using your metric (or the one from Shorter) would perhaps have similar characteristics.

"My metric says nothing about preference, only audibility. Preference is another question altogether."

Hmmm...not directly no but indirectly I think it must. The whole point if I am not mistaken is to better correlate measurements with audibility of distortion. It provides a factor that relates how distortion looks when weighted properly. Apparently the lower this value the better it should correlate with subjective sound quality because it means lower audibility of distortion products.

Therefore, I was taking audibility and "different" as a given in that someone thinks a correlation needs to be improved.

"but I do agree that some forms of crossover distortion caould be quite audible even on "poor" colored loudspeakers and yield a fatigueing situation. But I would describe this amp as "broken" in that case"

As nearly as I can tell from the measurements I have looked at nearly all complementary Class AB amps would be "broken". I would not be surprised if you looked at the measurements of these $150 pioneer receivers you use that you would find crossover distortion in their measurements and that it is likely to be audible.

"Blind, and I have acrtually done this exact test, the preference ratings will be random with no correlation to anything let alone a metric"

You have? Is it published somewhere? How many amps and what types? How many listeners? ABX or some other design? I would be interested in seeing those results.

What I find really strange though, Earl, is that you are not denying the difference in audibility of amps. You even admit that there is a possibility that perhaps amps with particular design characteristics would likely sound better, precisely because the audibility of their distortion is less according to improved metrics for correlating distortion audibility and THD. Yet you still insist that it is not important when most listeners would disagree with you.

Again, I agree with you regarding the importance of the speaker and speaker/room interface, however, if this is a constant then I would pose to you that changing the electronics will interject audible variations from that constant. These variations can be significant enough to severely affect the listening experience and the subjective "realism" of the reproduction. I have heard this too many times with too many systems over too long of time periods to believe that it is all in my head and not due to real environmental factors.

It can't be all psychological self-delusion. Pavlov's dog sure salivated when the bell rang but they also found that if once in a while he didn't get food the effect of the bell to stimulate the salivation response weakened greatly. Same thing with a pretty amp sounding better. The person may be able to convince themselves it sounds better for a while but after a while the amp either has to produce sound up to its looks or it will be replaced.


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  • Re: Thanks for the note - morricab 12/31/0510:27:25 12/31/05 (1)


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