Peavey Triple XXX combo distorted clean

[Danglin' Fury]

Hey all. I have the Peavey Triple XXX 212, 120 watt combo on the bench. The clean channel sounds pretty distorted. Whatever the problem is, seems to be affecting the distortion channels as well, as they sound very woofy and not as good as I've heard one of these amps sound. When I pick really hard on the clean, it seems like the signal wants to come through but backs off and sounds like I have an OD pedal in front of it. I put all new tubes in, both power and pre, and no change. When I plug into the effects return, it is very clean and bold, so it's not in the power section. I've used Deoxit on the loop, input, speaker, and line out jacks to no avail. I also disconnected the reverb in case that was affecting the signal, and it is still not good. Anybody see this before? Thanks.

[TomCarlos]

Does the amp look like this one? A single input jack with the switch right next to it? Perhaps the schematic (and circuit) for the Triple X head is the same as the combo.

You mention cleaning the Effects loop jacks with DeOxit and plugging into the return. But did you try plugging into the amp's input and using a small patch cable between the Effects Send and Return jacks? That would be another quick test to do.

Peavey_Triple_X_Head _Schematic.pdf

UPDATE: From your post, it sounds like the problem is not just with the clean channel, but the distortion channel as well?

[Danglin' Fury]

Hey thanks for your reply man. I do indeed have the schematic. The difference being, it does NOT have the reverb circuit in it. It's proven quite difficult to get it. And yes, I tried the patch cable in the effects loop. It still does it. Also yes, the distortion channels sound.... Almost fuzz-like. Pretty woofy but not a ton of pick attack like a Triple XXX normally has. But whatever the problem is, it is definitely affecting all 3 channels. New tubes all around, and I've tried multiple cables and guitars. I even plugged my 4x12 cab into it and it still does it. The clean sound is very anemic and sounds like I have an overdrive pedal on in front of it. But I plug directly into the effects return and it is very clean and loud. Very robust... It has to be something in the preamp. I'm about to start poking around in it as we speak. Lol

[g1]

I would suggest starting with power supply voltages, then preamp tube voltages.