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Technical and scientific discussion of amps, cables and other topics.

RE: That clears up a lot!

Dear Morricab;

You say that you have written many technical papers for refereed journals, but you include no citations, so I can’t tell whether you are the principal author or even identify what field you work in. I only know for sure that it isn’t audio, because your post exemplifies the perils of assuming that what you know in one field is applicable, willy nilly, to another.

I would be curious to read some of your work, if it is not so technical as to be opaque to those outside your field. And I would assume, if there were something in your paper that I did not understand or which seemed wrong, that for starters I just needed clarification from you. In other words, I would extend to you the professional courtesy of assuming you knew what you were doing. This you have not done for me.

You assert, quite broadly, that our entire paper is unscientific. The main basis of this startling generalization revolves around a concept called resolution, or resolving power, which is meant to be property of audio components. You go from there to the demand that we must measure our system’s resolving power before we can use it for subjective testing.

I’ll start with the electronics: Electronic components have no resolution or resolving power. It’s a scientific-sounding but empty concept coined, as far as I can tell, by subjective audio writers with no formal training themselves.

You demand that we test for this property by using our system and subjects to measure their perceived thresholds of distortion, phase shift and jitter. Jitter is a property of digital systems and there is no direct translation from it to any analog property at all, so let’s leave the top on that can of worms for now. Extra phase shift and distortion we can introduce fairly easily. But finding the thresholds for these things would be tests of the listeners and not of the system, because any good playback system has much lower levels of both than are perceptible.

These thresholds are well documented, and properly designed modern electronics do not exhibit anything like audible levels of either one, ever, unless they are incompetently designed or broken. The work documenting this stuff was done mostly between 1930 and 1970, but you do not seem to be familiar with the results. Did you know, for example, that for most musical signals, harmonic distortion becomes audible at a level of about three per cent?

Most relevant to the paper is that expensive electronics do not have less of any of these things than reasonably priced gear of the sort we used for most of our tests. The expensive stuff is in fact not better in any measurable way, and sometimes it is worse; many highly regarded tube components have ten to a hundred times as much distortion as good solid-state gear. This is thought by some to add “musicality” and does not seem to detract from the alleged resolving power of the components, to judge by the subjective reviews.

Regarding loudspeakers the situation is different, and what you are asking for in our playback systems makes a lot more sense. What I take it you are talking about is what I tend to describe in slightly different (and subjective) language – a sense of accuracy or overall believability in the sound; the distinctness of individual sound sources in precise locations; a rich and apparently precise sense of acoustical space; the audibility of subtle auditory cues within complex textures; a convincing illusion that you are listening through a transparent system and really hearing what’s in the recording; and a similar illusion that, with an exceptional recording, you are in the presence of the musicians. These things are talked about only occasionally in scientific papers, but we managed to sneak some of this language obliquely into ours because the recordings we found were as a group so richly endowed with these properties.

But we wouldn’t have heard all that good stuff if our system didn’t deliver it. We, and the others who helped us in our tests, not only like these qualities as much as anyone but need them, since (except for the audiophile setup) we are using our systems as professional tools, to make decisions about recordings and to investigate auditory phenomena, and sometimes to just kick back and enjoy the music.

The speakers have to play loudly without audible distortion, of course. It seems to be important to minimize early room reflections, so we set up our speakers that way (as do most audiophiles) and included an illustration in the article. It is absolutely vital that the room be extremely quiet; ours is, and we specified how quiet. Of course it’s better if the speakers have the apparent ability to disappear and leave only the recording – here again, the Snells qualify. I can’t convince you of any of this if you assume bad faith on our parts, but it is true anyway.

Respectfully yours, E. Brad Meyer



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