Loud hum from Marshall AVT?

Stompbox · 08-01-2012 04:20PM #1

Only happens when I trigger the overdrive channel, but there's a very prominent buzzing sound that won't go away. What could produce such a noise?

balducci · 10-01-2012 10:25AM

you've probably never changed the tube in the amp, chances are it's that.

8k2q1gfcz9s5d4 · 10-01-2012 03:38PM

balducci wrote: »

you've probably never changed the tube in the amp, chances are it's that.

I doub it, those pre amp tubes last a very long time. OP did it always hum or is it new thing? I used to own an MG and it always hummed on the OD channel

Stompbox · 12-01-2012 10:21PM

I can't recall if it always hummed. It's only when I turn it up pretty loud actually, maybe the sound is coming from the amp itself as opposed to out of the speaker?

Stompbox · 12-01-2012 10:21PM

I can't recall if it always hummed. It's only when I turn it up pretty loud actually, maybe the sound is coming from the amp itself as opposed to out of the speaker?

Stompbox · 12-01-2012 10:45PM

I posted a vid of the hum, if you could spare 30 seconds I'd really appreciate it!

Ravelleman · 12-01-2012 11:28PM

Video unavailable.

I used to get a hum from my ENGL a few years ago. At first I thought it was the tubes but in the end it turned out to be interference caused by the bathroom light, on the other side of my house.

Any CRT monitors or dimmer switches near the amp?

Stompbox · 13-01-2012 09:05AM

Video is available again. I think it takes a while for the video to become live on Youtube!

artvandulet · 13-01-2012 01:01PM

does it make the same noise with nothing plugged into the input?

happyman81 · 14-01-2012 02:30PM

Possibly a capacitor issue.

Squidgy Black · 14-01-2012 04:16PM

That could be anything. You're using a telecaster, presumably with single coil pickups, so it could simply be the hum from the pickups. Try it with a guitar with humbuckers, and possibly a different lead to eliminate this possibility.

It could also be a mains hum, or interference from a lightbulb. Try it somewhere else to see if that's the case.

Then again it could just be the amp itself. There's bound to be hum on an OD channel anyways, but this would be the least possible one in my opinion.

reniwren · 14-01-2012 05:42PM

its interference from something like a light or a laptop going to your single coils

Stompbox · 14-01-2012 05:46PM

artvandulet wrote: »

does it make the same noise with nothing plugged into the input?

Yep, it still makes the sound. When I turn the Volume or Gain fully up on the Overdrive channel, the buzz develops into a persistent ringing noise.

happyman81 · 14-01-2012 06:43PM

really sounds like a dodgy cap. is it still unnder warranty? or, coukd you bring it back to the shop?

Stompbox · 14-01-2012 07:36PM

It's not, it's a few years old. What's a dodgy cap? Capacitator?

happyman81 · 15-01-2012 12:26AM

Stompbox wrote: »

It's not, it's a few years old. What's a dodgy cap? Capacitator?

Yeah, my AC30 sounded just like that and it turned out to be a broken capacitor. Send it to a tech, I'd say.

Loud hum from Marshall AVT?

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