• 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 much THD are you allowing in your amp designes?

I generally am more concerned at looking at the distribution of harmonics on an FFT than I am with overall THD.

As a rule, proper biasing of a tube minimizes THD but with 2nd dominating, higher harmonics may be masked unless you look at the FFT.