I have a B-52 AT100 tube head with the matching straight cab. I bought it in July from Guitar Center. Recently I had been turning it on and it would have close to no gain at all; the clean channel works fine, but the gain channel is very low on volume and is barely distorted.

Unfortunately, the first time this happened, it was at a show. The following practice, it worked fine, but then I brought it into school for a BOTB audition, and had the same problem.

My friend who owns the same amp told me it was the fuse; that he had the same problem. he gave me a new fuse to put in. I did so, and the problem remained.

When that didn't work, I put the other fuse in to make sure that I hadn't taken out the old fuse and accidentaly put it back in. But the problem was the same.

The tubes seem fine. Only one of the preamp tubes lights up, but I remember that being the way its supposed to be. I checked at guitar center one time to make sure, and the tube all the way to the left was the only one lit. All the power amp tubes are lit up. But I don't know that much.

I've tried the selector on the back that switches it from Tube to Tube AB to Solid State. With no success. I have the impedance correct. I've tried everything.

What do I do!!!!
i just dont know if its the tubes or the fuse or my cab or what.

i dont think its my cab if the clean channel works.
probably a preamp tube, since your clean channel works fine. I would bet on it being one of the preamp tubes associated with your gain channel. Since the clean works fine, it's not going to be V1, and the PI/driver tube should also be fine. Does your manual give you a description of what each tube position is associated with?
"The fool doth think he is wise, but the wiseman knows himself to be a fool." - W.S.
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