Any Advice? Reverb Tank Proximity to Transformers Kills Signal

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Sunnyevan, Jan 11, 2019 at 8:51 PM.

  1. Sunnyevan

    Sunnyevan Member

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    This is a prototype amp with no schematic. For a while I have been struggling with the Reverb; the more you turn up the tone of the Reverb, you have to turn down the amount, otherwise it kills the signal, or vice versa.

    I finally figured out that the closeness of the Reverb tank influences killing the signal. When the tank is installed, so long as the out side is next to the power transformer, and the in next to the output, there are no issues, BUT, there is an insanely loud hum.

    If you swap it, so the out is next to the output and the in next to power transformer, this is where the problem occurs. I read, the in should be next to the power transformer to minimize hum. Anyhow, being next to the transformers kills the signal in this orientation. The further away the tank from the transformers, the more you can turn up the tone and dwell without killing the signal.

    The proximity of the tank to the transformers has no effect on the dry signal when the reverb is disengaged/off.

    Besides building a bigger cabinet, is there any shielding that can prevent this? Perhaps something I missed?
     
  2. HotBluePlates

    HotBluePlates Member

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    I'm not willing to guess what circuit you may have created if there's no schematic. There's no way to know if a wrong connection is causing all your problems.
     
  3. Sunnyevan

    Sunnyevan Member

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    It's a prototype amp from a large amp manufacturer that doesn't want to service it. It's never been released. There isn't an existing schematic.
     
  4. HotBluePlates

    HotBluePlates Member

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    You've got the amp; draw a schematic.

    If you can't draw a schematic from an amp-in-hand, you might consider whether it is wise to tinker inside it.
     
  5. CoyotesGator

    CoyotesGator Member

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    Now I’m interested.

    Care to share pics?
     
  6. zenas

    zenas Member

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    Yeah that was the reason Showman Reverb and Bandmaster Reverb heads were so tall.

    Never tried to shield a tank for that, maybe start with aluminum foil, since you've probably got some in the kitchen. Might have to ground it to the chassis or the the tank or not ground it, so a clip on jumper would be handy.
    Good luck!
     
  7. zenas

    zenas Member

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    Speaking of grounds, the shielding on the cables you the tank are making good contact at the connections and in good shape right? Those can really cause issues if they're bad somewhere!
     

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