Tube challenge!

Bill Layer blayer at
Sat Nov 20 16:16:54 CET 1999

Hi JH,

>Is a stabilized PSU desirable for audio tube circuits at all ?
>(Many say it's not.)

I guess that depends on the circuit's application. The sound of many 
"classic" guitar amps is related to the power supply's stability (or lack 
thereof). The small capacitor values and low purveyance of the vacuum 
rectifier create a supply that can be modulated by the transients in the 
signal. It's well known that you can destroy the sound of a some classic 
pieces by replacing the caps with larger values, or even parts of different 
impedance, ESR etc.

On the other hand, in hi fidelity applications, a rigid supply is always 
desirable, with the possible exception of localized degeneration used as 
negative feedback. Many high-end tube circuits employ vacuum-tube regulated 
power supplies, for several reasons. The fact that tube regulators handle 
high voltages well is a primary reason, but there is also a difference in 
the sound. The tube regulators have a more musical, less grainy sound than 
do solid state regulators... Believe it or not :)

|      "The" Bill Layer - Frogtown, Minnesota. U.S.A.      |
| Vacuum tubes, Analog, Motorcycles and Other Alternatives |
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| <blayer at> |  | <b.layer at> |
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