Peavey Valveking 112

[goldtop5]

I have this peavey valveking that sounds weak and distorted. I've replaced the preamp tubes, phase inverter tube, power tubes, and check for opened resistors. I didn't find anything. I've noticed a defective 4560 IC and replaced it, but it didn't resolve the issue. What could be causing this?

[Enzo]

Isolate the problem, is it the power amp or the preamp that is bad?

Apply a signal to the input and trace it through the amp, find out where it doesn't make the jumpe from stage to stage.

[goldtop5]

It looks like it's in both. There's distortion coming out the main speaker and distortion on the preamp: going from the send on the effects loop to the input jack of another amp.

[Enzo]

Well, if the distortion is present at the preamp out, it won't disappear going to the power amp. APply a clean test signal from somewhere else to the power amp input.

As to the preamp, as I said, apply a clean signal at the input and trace it through stage by stage.

[goldtop5]

Thanks! I'll give it a shot.