Bad Tube?

[getuhgrip]

I've got a Marshall VS265 with a tube in the pre. Lately it's started humming at mid volumes after hitting low notes. I can thump it up side it's head and it'll chill out momentarily.

Spose it could be the tube goin' south on me?

 

[Major Tom]

Try the $12 tube replacement b-4 you take it to a shop for a $125, 9 week wait repair. If it ain't the tube, you got a spare. I've never seen that specific behavior out of a tube, but being an electro-semi-mechanical device it seems very possible.

 

[foo]

I'm not sure what a VS 265 is.

If it's an amp, turn it on and let it get warmed up, then tap each tube very gently - the bad one(s) will sometimes make a hollow kind of clonking sound.

Did I mention do this gently?

foo