I own a newer Ampeg Reverberocket thats been acting a little strange lately. I keep getting this intermittent noise that can only be likened to a "revving" engine. The noise starts out quiet and gradually gets louder and louder. If I lightly bump the amp, the noise stops for about 10 minutes and then starts up again. I've had tubes go bad before (not on this amp) and it sounds nothing like a bad tube. Anybody have any ideas before I take this into a tech??

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My rig - MIJ jazzmaster (SeymourDuncan Quarter-Pounders) VintageRat–FuzzFactory–Line6 FM4–Whammy1–EHX Worm–Boss DD3–Boss TU-2–SuperHardOn=Ampeg Reverberocket, '74 Super Reverb

Sounds like you are describing a problem called "motor boating". It could be tubes or capacitor related. Try moving your preamp tubes of the same designation in different sockets and see if it helps or switch in a new tube for test. Preamp tubes are cheap and you should always have a spare. You may just have a funky preamp tube. The power tubes can cause this problem also but it is usually preamp tube or coupling cap related.