• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

What value for the bias resistor of a SE 6550?


2012-05-27 7:34 pm
What do you want your plate Pd to be? 30W? Do you know the formula for finding cathode current?
From what I have gleaned about the subject you would want to have the tube dissipate close to max. That is why I picked about 90% of max. I was using v=ir to calculate the current dissipated by the resistor.
My first resistor was 470 ohm but that was way to cold. If I recall that was about 60ma cathode current. I wanted to know what other builders had previously used in successful amps. cheers.