Ampeg VT-22 reverb feedback

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by uwe, Feb 22, 2012.

  1. uwe

    uwe Member

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    Hey,

    I just bought an Ampeg VT-22 and have some issues with the reverb. When I dial it to about 3/4 it builds up feedback within a few seconds. This is without anything plugged in and the volume at 0. If I rock the amp I hear the reverb tank banging loud and the feedback is gone, but it starts building up again. The reverb is also very very quiet when I play through it.
    I've read about microphonic tubes and the tank being mounted to tight to the case, but I don't have the amp with me right now. What else could I look for?

    Thanks!
     
  2. brucem

    brucem Member

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    That may have a lever/lock on the reverb pan, make sure it's off.
     
  3. zenas

    zenas Member

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    The lever thing and try swapping the tubes that run the reverb.
    If that don't do it's tech time.
     
  4. Ronsonic

    Ronsonic Member

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    It isn't unlikely that a 40 year old amp has clapped out or deranged suspension or springs or that one or more of the reverb transmission springs (the screen door springs) have broken and are laying in the pan doing nothing but picking up vibration.

    I wouldn't worry about the tubes or any of that at this point, but would go straight to the internal examination. Inside the tank is a chassis holding the springs and transducers, it should be supported by a spring at each corner. The reverb springs should extend between the transducers and not visibly sag.

    Replacing the tank is a fairly basic screw off, screw in sort of job.
     
  5. zenas

    zenas Member

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    Ronsnic you may well be right. Just MHO but I always start with tubes because 90% of the time that's it and if it ain't you have spare tubes.
    I have three Ampegs here now two from 68 to 70 and one from 62. The reverb tanks in all three are working fine.
    The amp may need a cap job. Easy way to tell is if it ain't had one it most likely needs one. The old PC board Ampegs are easy to work on as well.
     
  6. Ronsonic

    Ronsonic Member

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    For it to be a tube problem, it would have to be multiple failures. Bad driver and very mic'y recovery tube or a recovery tube that is both failed and very microphonic.

    I'm betting on the pan.
     
  7. uwe

    uwe Member

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    Turns out it was the reverb lever after all... sorry guys!
     
  8. zenas

    zenas Member

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    Agreed but why not start with the cheap easy stuff first. And in this case it was the lever. Now that's cheap and easy!
     
  9. Ronsonic

    Ronsonic Member

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    See, it was the pan. Well, the lever in the pan, but indeed the pan.

    Where's the toldjaso smilie?
     
  10. zenas

    zenas Member

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