• 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.

How biasing mA in tubes

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Thanks, I have other doubt: If I use a mu-follower like the attached schematic what is the right mA bias? 5mA across cathode resistor 470R?

Mufollower2.jpg
 
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Joined 2009
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If, using Ohms law, you work out the current flowing through the 33K resistor, the overall value will be clear and using proportional calculations the voltages can be calculated across the cathode resistors and therefore the current flow, which will be a constant.

So I have to measure 5mA accros each cathode resistor?

I = V / R

I know Ohms Law and use it.
 
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