Tube Amp Archive

M Fowler wrote:Isolated input jack?

Preamp grounding all goes to one spot near the input jack with an isolated input jack.

PI section grounds with filter caps B+1 through B+3.

What I have to change?
Thanks

martin manning wrote:Could it be environmental? Do you have fluorescent lights or dimmer switches nearby?

No. Plus I have played dozens amps in my basement, always with no hum problem. I think it's my fault this time.

Mark, without PI but with V1 and V2 amp was silent, with PI and no V1 and V2 same hum. I think problem is in PI section..i tried to put another 12ax7 but it's not a bad tube since I have same result with new tube.

You tried the basics first? Could just be a bad tube, it happens. Or a cold or missed solder joint. Yep. I found really strange that same hum came from two different amps. This make me thought that I made some mistake in both heads. I forgot to say heater and secondary are center tapped, and of cou...

Hi guys. My first message here. I'd like to ask an help from you, because I have a "big" problem in my two Rockets type amp. I don't be able to quite them as much as I want. I don't know if my problem is a ground problem or something more, but in two weeks I discovered and solved 50% of this hum but...