Excerpt - Lynn Olsen

This brief discussion of amplifiers is intended to point out how traditional
measurements result in unwise decisions for amplifier design. The lower
harmonics are nearly inaudible compared to the upper harmonics, yet they
dominate almost any THD measurement! The meter is steering the designer, the
reviewer, the dealer, and the consumer away from good sound.

It’s the classic tale of a drunk looking for his car keys under the
street-light, even though he suspects he lost them in a completely different
place. "The light is better here!" say the mainstream engineers,
mass-marketers, and magazine reviewers — but the key to good sound sure
isn’t where the audio industry has been looking.

If it were, why do stereo LP’s made 40 years ago, amplified with 65-year-old
direct-heated triodes, sound so much better than today’s digital sound played
through 0.001% THD mass-fi rack stereos? The differences between mass-fi and
true high fidelity are as plain as day to an (open-minded) listener.

We are in the odd position of discovering that as speakers get better and
better, the true merits of vacuum-tube circuits become more and more evident.
After all, even J. Gordon Holt gave the Crown DC-300 transistor amplifier a
Class "A" rating in 1971. At the time, the modestly-priced Dyna Stereo 70
received a lower rating - yet with modern speakers, the DC-300 is unlistenable,
and the Dyna just keeps sounding better. The entry-level EL84 amps of the early
Sixties (Scott 299, Eico, and Dyna SCA-35) sound remarkably natural and
realistic with today’s more efficient, and much more transparent, speakers.

There is no reason to believe speakers will stop getting better, since all
kinds of new innovations in materials science are on the horizon, and there are
major advances in computer modelling techniques every year. Synthetic diamond
cones, anyone?

It’s time to debunk the myth of "euphonic distortion" once and for all and
discover the genuine and subtle sources of amplifier distortion that people are
actually hearing. Once we find measurements that can actually help, rather than
hinder, it'll be easier to build electronics that are friendly to the listener

=== Andy Evans ===
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