Adjusting tube bias...

The VHT bias meter is a great tool to safely measure bias

@krelldreams


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

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

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.