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2 pups/stereo; both pots need to be on?

Discussion in 'Pickups & Electronics [BG]' started by billoetjen, Apr 23, 2009.

  1. Hi,

    I just modded my SX P clone by adding a Dimarzio Model One (DP120).

    I gave each pup its own stacked vol/tone, and wired the output from each vol pot to its own stud on a stereo jack (common ground). Using full stereo cabling everything works fine. That is, TRS instrument cable to a stereo Y splitter. I swap first one plug into my amp and I get the Model One. Then I swap the other output from the y to the amp and I get the P. Sweet.
    I take the Y out of the signal and use a Stereo to mono adapter (Hosa model GPP290 "• Sums stereo left and right to mono") and things get a little funky. I have to have both vols up to get a signal. I'd like to have control over which pup is on and how much. If I turn down one vol, it seems to turn down both. Hmmmm. :meh:
    Any ideas? Something obvious that I'm missing?
  2. Why would you want a stereo instrument and plug into a mono amp?
  3. That's a legitimate question...

    The separate channels are for studio work. That way, each channel can be mixed/eq'ed as befits the overall mix.

    I also haven't invested in separate rigs for live (as Billy Sheehan uses). That would be nice, but not on my horizon. Not that that wouldn't be coooool. ;)
    Anybody have any theories explaining why summing the two channels won't let them act independently?

    Thanks as always.
  4. If using a mono plug in a stereo jack, one of the "hot" connectors will be going to ground.

    That could be the root of the problem, maybe ?
  5. Using a common ground may be the problem, just a guess.
  6. Mohawk, thanks for the thoughts, but neither of the hots is getting grounded. I'm using a TRS cable; one end in the stereo jack, the other into a "summing" stereo to mono adapter. To test the layout, I tap a string against a pole piece on each pickup. They both respond with that distinctive "pop". That is, if both vol pots are turned up. If I turn one all the way down, both channels disappear.
    There is some room for adjustment. If I turn one pot all the way up and back off on the other, the balance goes the way I want. But, it would be nice to be able to have the same kind of control that I have with my other vol/vol basses. Curious.
    And, by the way, the addition of the Model One is exactly what I wanted to add to the P sound. A nice, thick, underline of BASS. Very authoritative. Almost too much for the 15" combos I have.
  7. wizay


    Mar 5, 2008
    I got the same conficuration on my attitude, look for an attitude schematic, maybe you get ideas :)

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