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Controlling the volume jump between series/parallel/single

Discussion in 'Pickups & Electronics [BG]' started by silky smoove, Mar 9, 2005.

  1. silky smoove

    silky smoove

    May 19, 2004
    Seattle, WA
    Okay, so I'm thinking about doing a Warmoth/Modulus bass. My idea is either a standard Jazz, or a dinky carved top P body, and a Modulus J-type neck. Now, here's where the fun starts. I'm planning on using 2 Nordstrand MM4.3 pickups (think of a Bongo, but with all of that crunchy Nordstrand goodness).

    Now, here's where it starts getting tricky. The MM4.3 pickup allows for operation in series, parallel and silent single coil configurations. Now, my thought is to wire these for series/parallel/single using a DPTT (double pole, triple throw, on-on-on) switch for each pickup.

    The problem I have is that when jumping between the settings there's going to be a noticeable jump in volume. Single coil being the quietest, parallel being a bit louder, and series being the loudest. If you think about it, on a Musicman Sterling they do the same thing (except with obviously a single pickup), and they do it without any noticeable jump in volume between settings.

    So, my question is: How do they achieve the three different settings of series, parallel and single coil without a noticeable jump or drop in volume between the settings?
  2. Lyle Caldwell

    Lyle Caldwell

    Sep 7, 2004
    Well, you can use resistors to pad down the output of the louder settings, evening them all out (all down to lowest common denominator) or you could use an active circuit to boost the levels of the quieter ones, potentially adding noise.
  3. luknfur


    Jan 14, 2004

    I don't use pedals but have a GEB-7 eq which is also a volume control. With it, you could do two of the three. I'm guessing there's a pedal you could probably pull it off with.

    But practically any adjustment to a bass results in an apparent volume change if not an actual one - pup blends, active boost/cut, tones, switching. Didn't know that about the Sterling but sounds interesting.

    Seems the 4.3 is a triple ala Sterling with the third coil on the bottom so guess you know you'd need a deeper route if that's the case. Carey has an MM 4.4 quad now that's not on his site yet - no bottom coil.
  4. mrelwood


    Dec 15, 2004
    Actually, in my experience on an individual passive MM style bass the single coil mode is only barely quieter than the parallel mode. So You don't have to worry about that.

    The preamp has different levels of boost for each setting. I don't remember the preamp schem exactly, but both the pickup wires and the selector switch wires go to the preamp, so it might be a bit tricky what they do in there.

    But it could be possible to tame the series mode with a resistor. This will kill the trebles quite a bit, so I would use a 1nF-2.2nF cap in parallel to the resistor (22K could be okay). It is possible with a regular on-on-on double pole switch like this:

    EDIT: Too tired. Stoopid mistake. I'll be back tomorrow.

    Disclaimer: Component values have not been tested, and will most probably not yeld pleasant results. Values between 10K-100K and 1nF-4.7nF should be tested. :smug:

  5. mrelwood


    Dec 15, 2004
    I tested this circuit with a Stingray copy, and it seemed very useful. However, some day I will investigate if a multiple component treble bleed would give more natural results. This was easily good enough for trying. There are still some gain differences, but they are rather small, and I consider them welcomed. Different styles require different volumes anyhow.


    EDIT: Darn. I just realized, that will raise the pup impedance from ~13K to ~113K, so the tone won't work. Have to think about this some more.

  6. A9X


    Dec 27, 2003
    Sinny, Oztraya
    That's how I do it in my preamp.