Please help with tube amp problem (volume/power issue)

[maddnotez]

Bought a VHT Pitbull used. Have had it a few months now, no problems whatsoever. Sounds amazing.

Then last night at practice, there is a part where I utilize the footswitch frequently. During that part my amp shit the bed.

It still works, it still produces noise. But about 70% loss of volume and power.

I used to run master at about 90-95% and my channel volume on 2. And everyone still says wow man ur too loud... But now I can max everything and still sounds very weak.

I visited other forums, everyone said check the power tubes, which was my first thought. The only thing is They all look fine. All glowing same orange color. Nothing looks broke, the fuses are both fine. What the hell.

This is my 2nd tube amp and I do not know alot about tubes, If a power tube goes will it cut the power/volume like it does now or will it just not work at all?

Also since they are still glowing does that mean they are still good?

Please help

 

[Sixtonoize]

The fact that they're glowing does not mean that they're all good.
Sometimes, the tubes that glow the brightest can be the most shot.

A volume loss can also be due to a preamp tube going - check the preamp tubes that are closest to the power tubes.
It's unlikely that it's a channel-specific tube, but it could be an FX loop driver, phase splitter or (if it's an UL) a power tube driver.

Have you tried tapping on each tube individually with the eraser-end of a pencil?
That's usually pretty good for weeding out a dead tube.
Usually you'll notice *something* when you find the bad one, be it a volume change, feedback, or noise.

If it's a bad power tube, replace all of the power tubes.
If it's a bad preamp tube, it's not as necessary, but still not a bad idea, to replace them all anyway.

 

[glip22]

Sounds like a bad tube . Replace your phase inverter tube first. One side of that tube could have gone which will cause weak output as no or a very weak signal will be driving two of your power tubes. I bet it's the PI. Usually the furthest awy from your inputs.