Right. It's not self-biasing, but fixed bias. Now, have I changed tubes in a fixed bias amp and not had it rebiased? You betcha! But I don't recommend it.
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Tubes for my Ampeg V4B
- Thread starter doobeye
- Start date
No they are not. Self biasing implies cathode bias where a large fixed resistor is in the cathode circuit to provide a positive voltage. This makes the grids negative with respect to the cathodes. The other self biasing scheme uses an electronic circuit to monitor cathode current and then automatically raises or lowers the bias voltage on the grids to keep that current stable. The V4 uses neither of these and is in fact a standard fixed bias amplifier. Any time a fixed bias amp gets new output tubes the bias should be checked and reset as required.
Paul
