Low bias current - Carvin TS100

[Helmholtz]

The bad news is that I still cannot use el34.

How much does the bias voltage at C44 and C9 change when you flip the bias switch?

Bias voltage value should be lower (by maybe 5V) in EL34 position.
E.g., 6L6: -45V, EL34: -40V.

[J M Fahey]

I've never found a technical justification of this 70% "rule".
At best it could be interpreted as an upper limit to avoid overdissipating at medium output with fixed bias.

Most fixed bias guitar amps are fine with 50% to 60%.
Biasing hotter than that is likely to reduce tube life without giving any benefit.

70% bias is internet madness/nonsense.

Tubes need to be biased beyond crossover distortion knee and no further.

Everybody complains "factory settings are too cold" ...... REALLY? .... I guess amp designers and Manufacturers should know a bit or two about them, donīt you think?

Specially more than any "Internet Guru".

[SacredGroove]

How much does the bias voltage at C44 and C9 change when you flip the bias switch?

Bias voltage value should be lower (by maybe 5V) in EL34 position.
E.g., 6L6: -45V, EL34: -40V.

I will check this tomorrow, after I'm home.