by bordonbert Thu Sep 08, 2016 8:22 pm
Hi there, welcome to the forum, we'll do our best to help but there aren't too many Triampers here as you can see. I don't have any experience of using the Triamp, but I do have access to a schematic so maybe that can help!
Forgive me for such a basic question but by '2A, 2B, 3A, and 3B' you are talking about 'Crunch1, Crunch2, Lead1 and Lead2' aren't you?
From what you say it sounds like the amp doesn't buzz without anything at all plugged in, is that right?
Also you say the buzz changes when you hit a chord then comes back as it fades. Do you mean it changes in character and can still be heard maybe behind the chord, or it actually stops buzzing completely?
The next thing I would ask you to do is to try all of the various outputs you can and see if they all include the buzz. Obviously the output to speaker will as it includes all stages, but does the DI output? Can you check the signal from the Fx Loop Out. Also check the Preamp Out signal to another amp.
This is a really odd one just looking at the schematics as the amp is organised in a very logical way. There is an input buffer triode specifically for the Lead channels and another shared by both the Clean and Crunch channels. After the Lead buffer it goes to the Lead preamp which uses all of its own stages and tonestack exclusively. After the Clean/Crunch buffer the signal is split to the Clean preamp stages and the Crunch stages which are also exclusive to their channels and their exclusive tonestacks. The power supply lines are also shared by the Clean and Crunch channels with Lead having its own. So far there is nothing shared by both the Crunch and Lead channels, which is where the problem shows up, and not including the Clean where it doesn't. If there is genuinely no sign of a problem in the Clean channel then we must assume it must be after the preamp stages but how it would isolate the Clean channel I can't guess.
Can you just confirm that the Clean channel definitely shows no sign of this issue while the Crunch and Lead all show it clearly?