Amp hum even with no guitar connected

[Marinblues]

Hi,

my amp is producing a constant hum. These are the symptoms:

1) hum with no guitar connected
2) hum does not increase by increasing preamp gain
3) hum does not increase when increasing pre-amp volume
4) hum increase only when increasing master volume.


What could it be? The output tubes? Grounding?

thanks

Marin

 

[proxy]

Re: Amp hum even with no guitar connected

Perhaps grounding, or maybe noise on the power line?

You can get noise on the power line form like flourescent lights and stuff like that. They make devices to clean the power going into your amp.

Maybe buy some power tube sheilds?

 

[Marinblues]

Re: Amp hum even with no guitar connected

Power tube sheilds?

 

[proxy]

Re: Amp hum even with no guitar connected

Preamp tubes most commonly have them, they have like a metal cyclinder that goes over them, this is for sheilding purposes, I believe I have seen the same for power tubes.