Seperating cathode cap/resistor grounds.

Discussion in 'The Workbench' started by stickyfinger, Feb 27, 2020.

  1. stickyfinger

    stickyfinger Well-Known Member

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    I have a hole in the back panel of my 81 2204 an want to make use of it. Want to add a hot rod switch that will add bypass caps for the 2nd an 3rd gain stages. Id like to keep it clean inside and not mess with other soldering as the amp is almost 100% original minus the mic pre in hole. Idea of adding caps from the cathode socket pin to the switch and grounding there. Resistor grounds will be stock and be grounded to the pots.

    Do the cap/resistor need to be grounded together??
     
  2. ampmadscientist

    ampmadscientist Well-Known Member

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    The ground for the switch could be run up to the same ground as the pots.
    But it might not make much difference.

    On these things it might make a POP when you switch the caps into the circuit.
    But there is usually a way to stop it from popping.
    A large bypass resistor around the switch will keep the cap charged up when you are not using the cap.
    Therefore when switching the cap into the circuit, the POP is reduced because the cap is already charged up...
    I'll try to make an example:
    bypass resistor.png

    Otherwise if the cap is not charged, the voltage of the cathode will suddenly be dragged down when the cap is switched into the circuit.
     
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  3. stickyfinger

    stickyfinger Well-Known Member

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    Thanks, I've experimented heavily with switching but always left out the resistor. I've seen how the big boys do it with relays and they are all ways quiet, may give it a try but it does have a small (though probably not noticeable effect) as show in sim, effect on the stock circuit. Simply I don't want to mess with the ground buss bar as the amp is clean minus this hole in the back.
     

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