• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Zener Bias

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alexistheo

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Joined 2004
#1
In the most recent audioXpress (apr 06), there is a push-oull 25L6 stereo amp. In it, Bob McIntyre uses two 7.5V zeners to bias each output tube. I was under the impression that zeners were noisy as cathode bias elements. Adding bypass caps to shunt any noise would seem to defeat the whole purpose of using them... so i'm curious: has anyone here tried zener bias of an output stage successfully?
 
#2
I haven't tried zener biasing audio tubes, but it works great in RF PA's 😉

The noise a zener gives off will be moot on an output tube. The driver or other low-level pre's maybe, but not on the output unless you have insanely sensitive speakers perhaps.
 
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