Adjusting tube bias...

I am not new to tube amps, but I am new to tube amps without auto bias.  My new (used) tube amp says to adjust the bias for the EL34 power tubes to between 0.3-0.35V.  Is this based on the amplifier or the EL34 tube?  I just got some winged C Svetlana tubes and wondering if the bias setting is the same when using these tubes?
D08feef2 7e0b 425e b127 2092d5719d6aaudiofreak32

Showing 2 responses by atmasphere

Its based on both the amplifier and the EL34 characteristics. For any EL34 going in that amp the bias setting will be the same. Be sure to check it one hour after warmup- you may find it higher. The correct bias setting will be what the reading is after one hour, not one minute.

A set of bias test points so you can plug in a more accurate meter might be a simple solution.