when i plug the speaker in and turn the amp on, as the tubes heat up
the hum gets louder. This is a fresh rebuild with new components. The
2 things i can think of are bad output tx or ground loop. I have only
1 ground for everything. any suggestions?
thanks,
jeremy

I have confirmed hum in both rebuilt amps and i know 1 tranny was good
when i built them. I am thinking ground issue?

Also it hums with no input at all...

On 5 May 2005 16:56:29 -0700, "lord_glum" wrote:

Also it hums with no input at all...

How do you ground the chassis?

Is there hum voltage on the filter supply (scope it)?

Pull the preamp tube - does it hum?

Pull all the tubes, does it hum?


I'm not sure what a model UA-1 is...

Ok some more data....
chassis is grounded at 1 point for everything.
with the rectifier and preamp tube no hum...
I did get rid of the hum on 1 of them by re-wiring the feedback ground,
but now the o/p tranny vibrates...

and i still have no output??? This floors me since i know the output
trannies are good....