Historical

Solid-state rebuttal

Editor: I must take very strong exception to your article condemning solid-state amplifiers in general and stating that the best of them sound like the best of the vacuum-tube amplifiers.

I built, along lines used by Acoustech, a 3-channel solid-state amp that makes my Citation tube amp sound sick. There is more apparent bass (although there is no measurable difference), the damping is much better, and triangular waveforms show no sign of the crossover distortion you described. This transistor amp doesn't add any glitches to color the music, and it sounds better than a good tube amplifier.—W. Q. Cochran, Hatfield, PA

We did not condemn solid-state amplifiers in general; all we said was that very few of the ones in commercial production sound as good as good tube amps, and the best of them sound virtually indistinguishable from the best commercially available tube amps.

A commercial product must be built to a price; a home-built one need not be compromised, so yours may well be excellent. The fact that it sounds better than a Citation tube amp is hardly pertinent, though. Your Citation may not be meeting its own specs, and even if it were, we do not consider it to be one of the very best tube amps available. Some of Citation's tube amps were prone to low-frequency instability, which could account for the improved bass you noted from the transistor unit.

The point in question is not one of potential quality, but of quality that has been available to date in commercial designs.—JGH

Elusive factor?

Editor: In your report on the KLH Model 16 amplifier, you said "it was very slightly bass-heavy (for reasons which escape us)..."

What happened to your powers of deduction? All you have to do is read the spec sheet to note that the KLH 16 has a rated damping factor of 4, which is lower than just about anything else on the market. Is there any wonder it sounded "very slightly bass heavy?"—Jim Stroup, Albany, NY

Little wonder. We just wonder how we managed to miss the connection.—JGH

Popped transistors

Editor: I'm having a puzzling and frustrating problem with my KLH 16 amplifier. In the four months I've owned this, I've had three failures of output transistors. The last time I got it back from being repaired, I loaned it to a friend who used it for over a month without trouble. The very day I got it back, one channel went dead again.

I never overdrive the amplifier. Most of the time, it is used to feed quiet background music to several speakers throughout my home.

Why would this thing be all right at my friend's house and useless at mine? Am I cursed, or what?—William Benton, Bronx, New York

Why don't you read instructions? KLH, and most other solid-state manufacturers, warns explicitly against making interconnects between the ground connections on the outputs. Evidently, this is just what you have done, in the wiring of your multi-speaker distribution system. Rewire your distribution circuits so as to maintain strict isolation between both sides of both speaker lines, or get yourself a tube-type amplifier that will tolerate cross-connection of the output grounds.—JGH