Master Volume Modification? want rid..

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by JamesHealey, Jan 21, 2008.

  1. JamesHealey

    JamesHealey Member

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    750
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    Jan 8, 2007
    Location:
    Leeds, UK
    I bought JCM800 1987 non-master head, and i really dont want it to have a master volume as it totally ruins the tone completely.

    I've done small modifications in amplifiers, eg replacing the odd resistor and biasing my own amps, i know how to drain the caps and not end up electrocuting myself but my knowledge isn't as great as it could be.

    i can photograph the inside of the amplifier and follow instructions to a tea.

    just need some guidance really.
     
  2. sliberty

    sliberty Member

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    NJ
    If you hate the way master volumes sound, don't install one - get an attenuator instead. Expect to pay $300 or so for a good one.
     
  3. JamesHealey

    JamesHealey Member

    Messages:
    750
    Joined:
    Jan 8, 2007
    Location:
    Leeds, UK
    it's already had one modded in i want to remove the mod.
     
  4. John Phillips

    John Phillips Member

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    If you can post pics of what's been done it will be easier to assess how much work needs to be done. It's possible to remove it no matter what, but it may be simple, or difficult.

    Have any extra holes been drilled? If so, you're as well to re-fit a non-invasive (tonally) type, which do exist. There are a couple which leave the circuit exactly the same as a stock non-MV when the knob is turned up full.
     
  5. JamesHealey

    JamesHealey Member

    Messages:
    750
    Joined:
    Jan 8, 2007
    Location:
    Leeds, UK
    it had a a Pre-PI type where u run a 1mega ohm pot at the back (wasnt drilled just replaced the DI socket which was still in there just bent back behind it. (DI now installed back onto rear panel). from this pot it had two fly wires to the 0.22uf cap near the treble.. and the other wire was to ground.

    Im certain this was easy enough to remove, and i removed it resoldering the 0.22uf cap back onto the board and it works a treat and sounds so much better.
     

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