Plexi Mods - Marshall Amp Modding Secrets!

Tone Stack Lift

If you’ve ever heard of ‘no-load tone controls’ or removing tone controls completely for a guitar, this mod is pretty similar, but for an amp. Basically it involves lifting the wire going from the middle pot to ground, thus taking the tone controls out of the amp’s circuit.

You could make this a permanent modification if you like the sound, but a far more useful solution is to make one of the amp pots have a second function as a SPST switch, and wire this mod to it. Just replace any of the tone control pots with a push-pull pot that has the same resistance value and taper, connect it up as normal, then use the two contacts of the switch to interrupt the mid pot’s ground connection as follows:

tone stack lift  diagram

You don’t have to make the mid pot the one with the switch, but do make sure its the mid pot’s ground that you’re interrupting when you install this mod.

The results are what sounds like an increase in gain and a slight difference in feel, and obviously the tone controls become redundant.Those looking for an EVH brown sound like tone might find this mod particularly useful, and its nice as it is very simple to perform, and easy to engage. Here’s a soundclip courtesy of  Kevin Andrigo:

text and images Copyright © Richard Baines 2010

Related posts:

  1. Switchable Tone Stack
  2. 2203/2204 Tone Mod
  3. “Cream Switch”
  4. V2a Cathode Switch
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