Peavey Envoy 110 Transtube (red stripe) question - crackling on sustained notes

[Alex_SF]

I have a Peavey Envoy 110 Transtube Series (model name is "Envoy II" on rear sticker; red stripe, pointy Peavey logo on front, made in USA). It works and sounds great, except that on sustained notes or chords I get a staticky crackling after a second or so, which interferes with the notes.

This occurs on both clean and lead channels, and at low and high volumes. I'd like to try and diagnose / repair the issue myself if possible, since bench fees for a pro diagnosis/repair are about as much as the amp would be worth to replace. Any clues on where to start looking would be appreciated.

Thanks,
Alex

[loudthud]

As an alternative to using an oscilloscope, I would use a simple signal tracer. Basically it's just some kind of audio amp with a speaker and a 1Meg Volume control on the input so it can accept signals of high amplitude. Then connect the Envoy to a dummy load resistor, play through it with a guitar and listen to the signal at various points along the signal path to determine at what point in the crackling begins. This will localize the problem to a few components. Can you post the correct schematic or post a link?

[Jazz P Bass]

That kind of noise tells me to recommend that you rule out the speaker first.

[Enzo]

Amen, it sounds like a rubbing voice coil. Disconnect the speaker and connect the amp to another one.