Guitar amp continuous humming

SOURCE: marshall 8080 valvestate amplifier

There could be a short in the rectifier diodes or in the transformer itself. Can you take some measurements inside the unit?

Let me know.
Dan

SOURCE: guitar amp make large crescendo-like noise, loud pop at end.

Same loudness, no speaker? This sounds (no pun intended) like a filter capacitor shorting out. Open it up and VERY CAUTIOUSLY look for what is making the noise. Filter capacitors can eject hot stuff. Very dangerous.

SOURCE: lots of hum from both speakers

Well folks I solved my problem and the amp has never sounded better. It had always hummed and now it close to stone quiet. The secret was it really never a problem with the amp. The problem was the result of either the pre-amp, interconnect cables, or the combinations of them. The solution came when I added a "drain wire" or ground to the cable I was using. There must have been a ground loop or some in-balance that required a wire to be connected to the earth (-) side at the source on the interconnect and then left unconnected at the other or receiving end of the interconnect. Anyway, no more hum, and the solution took some spare wire and solder.

SOURCE: A peavey special 130 guitar amp with excessive hum

I used to have one of these years ago!

What do you mean when you say 'switch to the off position'? Do you mean it hums when switched off?

Because the sound does not fully follow volume, it is likely a bad connection or power filter capacitor is not working.

Either way, it means a trip to a repair shop. There is nothing in there you can fix unless you are a repairman. Your local music shop should be able to coordinate a repair.

If this amplifier is like the 1983 version I had, its built like a tank and the fix should be easy.

Hope this helps!

Testimonial: "Yeah, it was a filter cap ( electrolytic )that was at fault. I replaced it my self, and now the amp is working fine.I suspected a bad cap, thanks! "

Scott Frye

• 1175 Answers
• Posted on Apr 17, 2010

SOURCE: Opening the speaker box, Peavey KB 60 Amp

Hi...

A couple of top screws and some on the back lip of the chassis . The amp slides out but be careful not to pop the speaker leads I own a KB50 and have worked on other KB amps.

Sounds like you need a new reverb spring set.

Peavey is very good for parts