Reverb in bfsr adding gain

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by bionic, Dec 30, 2017.


  1. bionic

    bionic Member

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    When i start to turn up my reverb i get a bunch of unwanted gain and start losing my high end. Anybody knows what gives? Check the 12at7?
     
  2. zenas

    zenas Member

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    This just start or always done it ?
    Definitely try another 12at7 and also the 12ax7 in that circuit, V4.
    Tubes do funny things sometimes and they're easy enough to swap out.
    But I'm thinking it's something else. Just can't think of what right now.
     
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  3. pdf64

    pdf64 Member

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    Yes, first steps are to get a known good tube in V4 and verify that ecaps, especially those associated with V4, are good, eg tack suitable ecaps across each in turn, checking for improvement.
     
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  4. Jeff Gehring

    Jeff Gehring Silver Supporting Member

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    Just for grins, measure the top lug (ie, not the wiper or the grounded lug) of the reverb pot to see if there is any DC voltage there. (There shouldn't be) If there is, you may have a leaky 3nF cap off the plate of the reverb recovery tube.
     
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  5. bionic

    bionic Member

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    Will check the above tomorrow. Thanks u guys!
     
  6. TimmyP

    TimmyP Member

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    For reasons I don't understand, I have seen this happen when the tank was bad.
     

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