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My amp is making a very noisy hissing sound during playing and when i'm not playing how ever the hissing stops when i put the amp into standby mode to keep the tubes warm whilst idle..

The amp also makes crackling sounds too.

I have a 6505 combo peavy amp. . what could this sound be?

Any help is much appreciated.

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Kapt.Krunch Sat, 11/10/2007 - 16:00

Following is one of the best places for tube amp questions:

http://music-electronics-forum.com/home.php

Could be a few things. (It stops in Standby because it's basically cutting off the output). Trust me, sign up there, and ask these guys the question. I know a couple of them personally, and they are some of the best amp designers, builders, and techs in the country.

Goods luck,

Kapt.Krunch

RemyRAD Sun, 11/11/2007 - 22:07

When you are in standby mode, plate voltage is switched off, so, no electron flow. Only the filament heater voltage remains on. That's for a tube amplifier.

In a transistor amplifier, in standby, the amplifier input is most likely shorted. That's not the guitar input but the amplifier and put post guitar preamp. That's why you don't get a thump when switching it back into operational mode. It's not interrupting anything in the power supply.

But bigdaddybluesman probably knows better than me since he builds guitar amplifiers. And I don't work on those things. Never have. That's obvious isn't it?

Obviously nutty
Ms. Remy Ann David

Kapt.Krunch Mon, 11/12/2007 - 02:59

He's moved on to the other forum, but I suspect he'll need to take it somewhere to have it looked at. (It's a tube amp). He seems reluctant to pull the tubes, inspect the pins, and reseat them. Maybe it was that standard WARNING about being careful that unnerved him, even though I explained it's unlikely to get buzzed simply pulling tubes with the chassis still installed, and the amp unplugged :?

Kapt.Krunch

moonbaby Mon, 11/12/2007 - 04:23

THe 6505 is a tube amp. It is virtually the same as the 5150, but a contractual dispute with Mr. Van Halen led to the name change. The 5150
is notorious for microphonic peamp tubes that will "Go Philly" on you (that's hiss,spit, and whistle). Putting the amp in Stand By simply stops you from hearing them.