Amp Specs esp. DampFactor : Citation, Adcom, etc.

Atmasphere, at the risk of sounding completely ignorant... why hasn't somebody done what you're proposing? This sounds brilliant, simple, and straightforward. In fact, I'd think that this sort of testing would supply much of the sort of information that I'm looking for.

It isn't that I disagree that each piece of equipment won't sound different, and I certainly agree that what sounds 'good' is subjective, but the methodology behind the sound reproduction should be measurable meaning that it should be possible to say something like: okay, you are looking for this sort of sound, for this sort of speaker, etc. Then you should be looking for amps with these characteristics.

The problem as I see it right now is that if none of these measurements have any value, then how can any of these judgments be made. This is why, at least in part, I think your idea is great.

One last note: about not measuring what is important to the human ear. I'm going to go out on a limb and say that this is likely not true. I can't say for sure, but in my field I research a fair amount of psychology regarding military deterrence and I am constantly impressed at how far the psychological and biological sciences have come in recent years. My point is that I would be shocked if no one has studied the interaction of the human brain, our in-built hearing, and how it interacts with music. Any study such as this would lead, inexorably, toward a better understanding of what appeals to the human ear (in general) and what does not. There are cultural issues here besides biological ones, but momentarily putting these aside, I believe you'd find that, in fact, what we hear, how we hear, and why we like certain things can be measured to a certain degree. To extrapolate, this would explain why certain types of sound reproduction--maybe using tubes?--remains popular even though arguably inferior technologically.

"...The result would be examined for odd-ordered harmonics so a listener fatigue/brightness rating can be assigned. Then the lower ordered harmonics can be analyzed so a low-order coloration (warmth, caramel, syrupy) value can be assigned. "

I believe that John Atkinson from Stereophile does this kind of measurments (his input signal can be subject of discussion) and looking on distortion spectrum - as you discuss above - I have some idea of the sound of the equipment - at least its midrange.

"A lot of research has been done since then, but none of it has been incorporated into the tradition of measurement, and so we have the experience of not being able to tell much of anything about the sound of the amp from its spec."

Simon Thacher from Spectron did study of the rlation between reproduction of musical peaks and listener fatique:
http://www.enjoythemusic.com/magazine/manufacture/0708/index.html

I beleive that Spectron amps are one of the best in that regard - of course, for easy load speakers you don;t need that amount of (distortion-free) power.

So, slowly but we still are moving along to understand relation between some measurments and some aspects of the sound.

Cheers

Atkinson's measurements are with steady-state signals. They tell you *something*, but how the amp behaves with a non-repetitive waveform is really much more important. In my opinion.

Aewhistory, you might be surprised to find out that research about the way the ear hears and how the audio system interacts with that, has really not been dealt with all that much in a way that is not classified.

I have heard of some research that has been done recently (in the last 3 years) that shows that if human hearing rules are not respected by the audio system, the process of analyzing the music by the brain moves from the one area to another. To be more specific, if the waveform is fast enough and lacking manipulation, the limbic system does the processing, but if too slow and certain harmonics are added, the processing is done by the cerebral cortex (emotional vs intellectual). I understand that they have hard numbers on that- on where the transitions occur. Fascinating stuff!

Hello Athmaspere,

LOVE your posts !!!!

I said that John Atkinson " input signal can be subject of discussion" and this is exactly what you did !

Even more interesting your comment: "... if the waveform is fast enough and lacking manipulation, the limbic system does the processing, but if too slow and certain harmonics are added, the processing is done by the cerebral cortex (emotional vs intellectual). "

Is exactly the same that Simon Thacher of Spectron wrote in the article I referred to:

"...The exploration of the origin of "listener fatigue" is extremely interesting, at least, for this writer. We believe that when our subconscious mind detects a small unnatural trace of distortion in reproduced acoustic music (which is not recognized yet as a very low level irritant by the analytical part of our brain) it activates a subtle alarm. This forces the listener into the tense or alert mode. Indirectly supporting this hypothesis is the common description we hear from Spectron users who utilize the two powerful monoblock amplifiers (7 kW peak power, each): "how relaxing" is my listening now "

Analytical part of the brain is the cortex, of course as you pointed out and emotional (or subconscious mind as Simon calls it) is our old reptilian brain

Its amazing - only from both of you I hear CLEARLY and bearly identically how audio engineering is related to our "undertsanding" of music

Seriously, I doubt that anyone could make serious progress in an audio design without understanding how the human ear/brain system works.

Some of this research is very new. The bit that I mentioned about how the processing moves from one part of the brain to another has only been done in the last 2-3 years. Intuitively, I think a lot of designers suspected something like that, hence some systems that invoke toe-tapping and the like; but its nice now to find out that the subjective experience is real and to have objective numbers to back it up.

That, IMO, is what the objective approach **should** be. Otherwise, the bench measurement rules amounts to the Emperor's New Clothes.