[pink snare]

My tube amp has been sounding kind of muddy lately... sometimes it will even fluctuate between muddy and clean without cause or reason.
I'm wondering if my tubes might be blown? They aren't really that old by any means, but I just don't know what else would cause an otherwise perfectly good amp to sound cruddy.

[BillSPrestonEsq]

Originally Posted by pink snare

My tube amp has been sounding kind of muddy lately... sometimes it will even fluctuate between muddy and clean without cause or reason.
I'm wondering if my tubes might be blown? They aren't really that old by any means, but I just don't know what else would cause an otherwise perfectly good amp to sound cruddy.

actually thats a classic symptom of a dirty effects loop.

[Major Tom]

Pull each tube out, and re-insert it a couple times. Try the effects loop thing BSPE suggested (clean the contacts on the switch of he jack, or test it with a "jumper" cable from the FX out to FX in) if your amp has an effects loop. If those don't fix it, replace the tubes one at a time (or the power tubes as a set if you have a replacement set) with your spares and see if that fixes it.

Of course, you also have to check external devices too - cord, pedals, guitar, etc. - any of those may also be causing he problem. Substitute, or eliminate each one to see if that is causing it.

[jerrydyer]

well, are they JJ's by chance? They have a high rate of failure. A power tube on its way out might do that. Runaway bias can cause that. Have a tech look at it on a meter see if it stays in one spot or not.

[RubberChipmunk]

Originally Posted by jerrydyer

well, are they JJ's by chance? They have a high rate of failure. A power tube on its way out might do that. Runaway bias can cause that. Have a tech look at it on a meter see if it stays in one spot or not.

I use exclusively JJ tubes (with the exception of 12BH7-types, which they do not produce), and have never once experienced an issue with one of their tubes failing.

[mulletman]

I've used only JJ's in my Orange since pulling the stock tubes out. No failures to report....

[Gojo03]

I haven't had any problems with my JJs either....