Squealing amps and tubes

[ChristopherDawn]

Hey, I'm using a 5150 on the lead channel with the pre gain set to about 6 and the post gain around 4 or so. The squealing in unbearable. Everytime I stop playing it rears it's ugly head.

Now my friends were fooling around with it the other day and took a look at the tubes and said they're different sizes? Two of one size two of another. I don't know what exactly they mean because I haven't seen what they're talking about yet (I'm assuming they're not talking about the preamp tubes and the big tubes [don't know what they're called, haha]).

I know the guy who sold it to me said that he put groove tubes in it, but if they're unmatched tubes could they cause extra noise and squealing from the amp?

What's the best (or some) method of taming this irritating noise?

 

[Outlaws]

The big ones are called Power Tubes.


You need to take a look for yourself and get back to us.

 

[fenix]

Make sure all the power amp tubes match. Make sure the preamp tubes match as well, althought I don't think that's as important.

A mixmatch of tubes shouldn't be causing the squeeling. My friend has a 5150 and it squeels as well. But that's because he knows nothing about decent tone and cranks the shit out of his highs. This could be the problem.

Another problem could be your cables. Faulty cables can sometimes cause squeeling.

 

[Major Tom]

Could be a lot of things, just a couple thoughts:

Sometimes reverb circuits will do that, if you are using it, try turning it down some.

As mentioned above, try a diffferent cable.

Try a different or new preamp tube or 2 in each position. If you don't want to spend any $, at least try swapping them around into different positions. I would guess they are all 12ax7's. If you run this thing at a high gain level it will be more prone to problems due to microphonics and whatever - you will need "high grade" pramp tubes - ones with low microphonics, etc.

If you have another set of power tubes, try them.

A very common problem that could cause that is that one of the solder connections on the input jack has cracked - the one you use all the time. Try wiggling the plug a little, and or try the 2nd input jack.

Other than stuff mentioned above, could be one of many electronic components in the amp going/gone bad.

Does it only do this at very high gain levels?