Tweet
My fender red knob twin just on channel one (clean channel) gives this crackleing feedback. It acts as if cable is plugged in the jack. Tapp on the jack or amp itself act just like a mike hooked up to it. Just like tapping on a live mike. Transformer and tubes are all good. THanks for the help.
-
-
"Tapp on the jack or amp itself act just like a mike hooked up to it. Just like tapping on a live mike. Transformer and tubes are all good"
You may have a microphonic preamp tube or a dirty tube socket. Try another 12ax7 in the first preamp tube. If that doesn't help try cleaning and retentioning the socket. If that doesn't work remove the first preamp tube and tap the amp in the same way that causes the problem. If you still have the problem with the first preamp tube pulled, pull the second preamp tube and repeat. This way you can isolate the problem.
Chuck"Take two placebos, works twice as well." Enzo
"Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas
"If you're not interested in opinions and the experience of others, why even start a thread?
You can't just expect consent." Helmholtz -
Before you bust it open, try snugging down on the jack and pot nuts - some of these amps rely on a mechanical connection to ground the jacks and pots.
Next step would be to try swapping some preamp tubes around.
See R.G.Keen's Tube Amp Debug PAge for more suggestions (and important safety warnings).
Hope this helps!Comment
-
I had a similar problem on an evil twin (post red knob) amp.
The solder connections under the molex connector on the middle board had broken/failed. Touched them up and was good to go.Comment
Comment