musicman 212 sixty five question

[donegone]

65 watt amp only conducting 60mA at full power. EL34 output tubes. 1k sine wave at .1vac input signal. Output voltage of waveform = 16.12VAC. 460VDC on the plate of the EL34's and 300VDC screen grid voltage. The EL34's at full power are only conducting 60mA. Seems very cold. I know these amps when at idle have little to no conductance. The problem with the amp is that it is producing output that sounds distorted. Sounds like cold tubes to me. Suggestions?

[Jazz P Bass]

What is the DC resistance of the speaker load?
If it is 4 ohms, that is 65 watts.
You need a scope to nail an early distortion problem.
How else can you prove out a preamp or a power amp problem.
You could start by checking your opamp Vdc rails.
Just my opinion

[Enzo]

Don't worry about what the curent seems to be through the tubes, worry instead about what signallevel is hitting the speakers. Jazz alluded to the same thing.

Power output is not determined by DC resistance, use the nominal impedance - AC resistance. 16VAC across 4 ohms is indeed about 65 watts.

RUn a sine wave through it and scope the result. The nature of the distortion often suggests its source. Then trace the signal through the amp to find where it goes astray.