Not feedback squealing..just annoying squealing

[bombtek]

What causes this in a tube amp?..its VERY random it comes and goes..cannot MAKE it happen..it just happens on its own quite often. Keep in mind, I just buy em and play em...I do NOT try tube swaps, rewire it or anything like that. Hell I have never even unscrewed the back of the amp . So any insight as to what might be causing this and perhaps a quick fix solution would be greatly appreciated.

[Hellbat]

Maybe one of the tubes is going microphonic? I think there is a way to tell by lightly tapping on the tubes while the amp is on, but I don't know the specifics as to what kind of noise is considered good vs. bad.

[bombtek]

Maybe one of the tubes is going microphonic? I think there is a way to tell by lightly tapping on the tubes while the amp is on, but I don't know the specifics as to what kind of noise is considered good vs. bad.

I dunno..if I punch (yes punch ) the side of the amp it goes away ...comes back when it wants to, but it does go away with a slight shock to it. I'm thinking SOMETHING is loose in there.

[jgcable]

#1. You can't just "buy them and play them" with tube amps. You should be using solid state or modeling amps.
#2. Random squealing is one of the following:
A preamp tube is going bad (microphonic). Swap the tubes around and see if the squealing goes away. BE CAREFUL. THERE IS EXTREMELY HIGH VOLTAGE IN THAT AMP EVEN IF ITS NOT PLUGGED IN. IT COULD KILL YOU!!!!!!
A bad instrument cable could make your amp squeal although its rare
One of the pickups in your guitar is going microphonic and either needs to be replaced or potted.

[bombtek]

#1. You can't just "buy them and play them" with tube amps. You should be using solid state or modeling amps.
#2. Random squealing is one of the following:
A preamp tube is going bad (microphonic). Swap the tubes around and see if the squealing goes away. BE CAREFUL. THERE IS EXTREMELY HIGH VOLTAGE IN THAT AMP EVEN IF ITS NOT PLUGGED IN. IT COULD KILL YOU!!!!!!
A bad instrument cable could make your amp squeal although its rare
One of the pickups in your guitar is going microphonic and either needs to be replaced or potted.

What would be the safest way to discharge any and all voltage from the capacitors (or whatever it is holding the voltage in) once the amp is unplugged?

[Grandturk]

Swapping tubes is not going to blast you through the wall. Rummaging around on the inside of the amp with both hands and a screwdriver might.

[Nimitz]

My 5150 does this sometimes, I took off the back plate and one of the preamp tubes is not seating very well I just push it in a little and it goes away.

I would stop punching the side of your amp while the tubes are hot, that can't be good!

[Frigo89]

Swapping tubes is not going to blast you through the wall. Rummaging around on the inside of the amp with both hands and a screwdriver might.

never complete the circuit! LOL

reminds me of Trout opening day last year... That goddamn fence...

[RacerX]

Swapping tubes is not going to blast you through the wall. Rummaging around on the inside of the amp with both hands and a screwdriver might.

What about just ONE hand & a screwdriver?

[Chief_CrazyTalk]

Do you have a voltmeter? You could measure the DC voltages on the filter caps before getting inside the amp. But you shouldn't have to, to change preamp tubes.

I've used a 1/2W 1K resistor with clips on both ends to discharge the filter caps. It's what I had on hand, worked fine.

[MakeAJazzNoiseHere]

Glass doesn't conduct electricity.

Yeah, it sounds like you've got a bad tube. Get a spare and start swapping.