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?
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Showing 1 response by krelldreams

Hi all. I’m hoping that someone reading this thread will be able to help me. I am also not new to tube amp use, but most of the tube amps I’ve had have had a built-in method to test bias. I bought a 1961 HH Scott LK-150, which has a bias meter on the front panel. HOWEVER.. it works only when I turn the amp on its right side! This amp weighs nearly 50 lbs, and the edges are sharp, plus it doesn’t sit up nicely on its side, which means I have to balance it with one hand while I press the bias buttons with the other hand. If bias has to be adjusted, I need to ask for a third hand. In addition to this odd process; How do I know this meter is accurate after 58 years?? The amp works well, and sounds awesome actually. Someone please suggest a better way to accurately bias this amp. I will be very grateful. Jerry