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YAQIN MC-10L Amp Biasing

Hello all,

I am new to tubes and just picked this amp up. I'd like to know if anyone can help with biasing the tubes. I am still waiting for it to come in the mail. I'm looking to change the stock tubes with better tubes and want to know how to go about adjust8ing it when I do change everything out.Any and all info is appreciated.



karodimitrov's picture

Re: YAQIN MC-10L Amp Biasing

With variable resistors 50K should get 0.3 to 0.4 volts at the control points TP+ and TP.This is a drop on the 10 ohm resistor and equates to 30 to 40 mA anode current on EL-34,which is normal for class A amplifier.

karodimitrov's picture

Re: YAQIN MC-10L Amp Biasing

All this you must do without signal on inputs and with output resistor-equivalent of your speakers.It's better to wait to warm up amplifier for a half hour before adjusting.