Welcome to Issue Two
This month's issue continues the unbalanced to balanced article and offers a trick for reducing the power supply noise from the output of an SE amplifier. Noise, its causes and elimination, will continue to be explored in future issues. The motive is not hard to find.
Noise constitutes a large part of what is condemned as the "tube sound," by those who favor solid-state electronics. Few tube supporters would defend hiss or hum as being euphonic. Noise stands guilty as charged, as it robs the musical experience of subtle nuances. Much of what is magical in a great recording is the air, minute details, and weak hall reverberations that make the recording come alive in our living rooms.
By masking these subtleties, noise reminds us that what we are hearing is not live, but only electronically reproduced. Of course, live performances are often marred by coughing, hacking, talking, creaking chairs, and glass clinking. But this noise is random and sharp, unlike the continuous and dull drone of power supply hum; no one in the audience imagines that he is hearing a reproduced musical event in his living room because of this live noise. (In fact, a few rare recordings so perfectly capture this live noise that its reproduction actually helps to convince us that what we are hearing is live.)
Given the choice between low distortion and low noise, choose low noise. The difference between .1% distortion and .01% distortion cannot be heard; a reduction of noise from -60 dB to -80 dB can. If you want to improve the sound of your tube equipment, lower the noise. Of course, low noise and low distortion are not mutually exclusive and it would definitely be better to have both.
Here is the irony of the situation. Most solid-state gear is very quiet, because of the low distortion race among stereo manufacturers. In order to please the total harmonic distortion meter, an amplifier must be both clean and quiet, as the meter cannot distinguish between distortion and noise. Whereas, the tube audio designer, having no faith in total harmonic distortion measurements, holding to his belief that no meter can beat his ears, forgoes the requirement of extremely low noise operation.
Some tube audio designers are very pessimistic about the noise given off by their designs. They tell us that the vacuum tube is an inherently noisy device and that it is simply not