More On The Great Preamp Myth
"Witchcraft" On Trial
The BAS Speaker Volume 8 Number 1 & 2 October 1979
At this writing, I am in Japan on an engineering assignment for one of our companies. While relaxing this evening, I decided to catch up on my reading and have just concluded Michael Riggs' article on "The Great Preamp Myth" (June 1979 Speaker).I commend his literate style, but I don't agree with a single word he says, especially the last sentence. Perhaps I believe in witchcraft, because there is no question in my mind that sonic differences between amplifiers and pre-amplifiers do exist and are detectable by trained listeners.
This morning's engineering session was a prime example of the hearing mechanism's uncanny ability to identify subtle differences in amplifier design. The first problem, which manifested it-self as a masking of the more audible frequencies, was quickly resolved by supplying more cur-rent to the input stages. I won't bother the membership with technical gobbly-gook, but this problem exists in many audio components and can usually be remedied quite easily.
The other sonic problem was somewhat tougher, but we got a handle on it rather quickly. Judging from the circuit diagram, and having listened to several designs of this type using similar small-signal and output devices, I knew that the amplifier should have sounded spacious and clear, with no high-frequency "bite" and lots of air around the instruments. But this was not the case. Something was seriously amiss, because what we heard was just awful. Highs were too sharp (yet IM measurements were in the mud), and the balance between the middle bass, mid-range, and highs was strange. In plain language, the amplifier wasn't musical.
While discussing the problem, I recalled a conversation I had had with Dr. Otala a month or two earlier, in which Dr. Otala (academician that he is) went into a long and enlightening discourse on why switches, relays, and so on create sonic anomalies. Remembering what he had said, I gave odds that the offending component was the amplifier's output relay.
After trying three other relays with different types of contacts, pressure, construction, and so forth, we concluded that all of them produced differences in harmonic articulation, balance, and most importantly, overall clarity. Two of the relays added stridency to the sound, which could only be attributed to dynamic distortion (probably intermodulation effects from the contacts).
Imaginary? Witchcraft? Not so! Pure scientific fact, even though we can only speculate as to the exact distortion-producing mechanism. Four trained listeners identified the sonic differences 100% of the time, and I'll settle for that.
Someday, if I have time, I would like to show you how much preamps (and amps) really do vary. I'll perform my witchcraft, and I can assure you that you will hear differences that are not the result of RIAA equalization or sound levels. We hear them every day, and we are perfectly sane, logical professionals who have been in the high-fidelity business for many years and have learned not to accept anything at face value. However, we also recognize that there is still a great deal to learn about high-fidelity design and how to conduct accurate listening tests. To call sonic differences between preamplifiers a form of witchcraft is hardly professional or worthy of the editor of The BAS Speaker.
Mike Riggs Replies
Mr. Kuby's letter, which boils down to "I know there are mysterious sonic differences between amps and preamps, because I hear them, " begs the question. This is "pure scientific fact"? If so, where is the evidence? The point of the articles in the June Speaker was that stringent controls are necessary for valid listening tests. Without them, prejudices and extraneous variables will contaminate the results.
In the absence of detailed information on how Kuby's tests were conducted, it is impossible to assess their validity. However, I might suggest one obvious problem. Kuby guessed that the output relay was causing sonic problems. That gave him an emotional stake, however small, in the outcome of the experiment. Nothing unprofessional about that — just human nature — but un-less accounted for in the design of the experiment, it could strongly bias the responses of all the listeners.
Recently, Dave Carlstrom told me a true story about a friend of his who was designing a tube preamp. Every time he modified it, he listened to it, and every time there was an audible improvement. After a series of such changes, he noticed he'd come full circle, back to the original design. It still sounded better. Just human nature.
Every properly controlled test conducted to date has yielded negative results. I am willing to change my mind (I already have, once, there having been a time when I would have agreed with Kuby), but only if presented with some firm, genuinely scientific evidence. Unsupported assertions won't do it.
Finally, I'm rather at a loss as to what I have done that is not "professional". Surely Mr. Kuby does not mean that expressing an opinion contrary to his, based on strong evidence from carefully controlled experiments, in bylined article is unprofessional? Or does he?
And a Timely Comment from Carlos Bauza
The reprints in the June 1979 Speaker relating to "The Great Preamp Myth" were quite interesting. I can see that this is an issue of the gravest concern to golden ears, manufacturers, reviewers, and audio marketing people. It is also a natural for the BAS whose underlying principle is debunking myths for the benefit of the hobbyist.
Reading the editorials from the underground press, I find it easy to imagine that the political campaign-makers from down here have moved up there to a more profitable market. It is disturbing how a matter such as this can lead to mud-throwing and similar tactics. Whether this is right or wrong, it certainly resembles political campaigning. I'm not sure whether political tirades against an opponent are in the realm of truth, or in some realm which truth forgives.
All the reading I have done about hi-fi during more than fifteen years has led me to one principal thing: acquiring a taste for the neutral — for equipment that does not add or subtract, that does not alter what is supposed to be the true sound of music.
This is the main thrust of all hi-fi publications. In pursuit of this goal, they try to explain how certain components approximate the sound of music, but they stop short of recommending a purchase, heaven forbid, because that is a personal decision. Nevertheless, they produce a de-sire for components with certain specific qualities.
Many audiophiles defend accuracy as an absolute value. But this taste for the accurate is not innate. It is an acquired, learned preference. To give an example of the non-absoluteness of taste, consider that for three centuries half of all girls in the English-language countries were named Elizabeth, Mary, or Anne (boys were John, William, and Thomas). It must have felt in-explicably correct to be named thusly; during those three centuries one would have felt dislocated to be named anything else. Today, other names feel correct in the context of current taste: Jason, Brian, Jennifer, Nicole, Ryan, etc. Maybe three centuries from now we'll develop other tastes in the realm of audio. Sometimes I wake in the night pondering this contingency, and wonder if the accountants of audio publications do the same.
As for me, my taste is already formed. I seek a reasonable facsimile of the sound of live music. It does not matter to me whether preamps sound alike, nor does it matter who says it. I am my own authority. I choose equipment according to my taste, regardless of editorial opinions or test reports.
Yes, test reports are useful to me. The ones Julian Hirsch writes are meaningful to me because I can relate his results to my own use of equipment in the past, and can integrate them with present experiences. The underground press is also useful, but I read them with the saltshaker by my side.
So, while the great preamp myth is being resolved, what you should do is to trust your own ears, form your own criteria, and act on your own personal feelings. But don't club people over the head with your taste. It's better to hear music with friends than alone.
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