How do I wire a MM/J configuration?

Discussion in 'Pickups & Electronics [BG]' started by IotaNet, Mar 19, 2006.

  1. IotaNet

    IotaNet Supporting Member

    To the Group -

    I have an OLP Tony Levin Signature bass on the way and I understand that it does a pretty acceptable Stingray imitation. That's cool but I'd like to give it some additional versatility.

    It comes stock with an MM-style pickup and a 9V preamp with V/B/M/T pots -- but I don't know who manufactures the pup or the preamp.

    I've spoken to my bass tech about adding a Jazz pickup in the neck position (specifically a Seymour Duncan Jazz stack in order to avoid an SC hum) but I'm not sure how to have him install the wiring & switching.

    What I was thinking about was:

    • Changing the volume pot to a stacked volume/blend
    • Having a series/parallel switch. In position one, both pickups would be in parallel. In position two, the pickups would run in series.

    I do know that many MM pickups are actually configured as TWO pups and there is series/parallel switching between them. However, I don't know how the electronics in this particular bass are set up. I also know that there are some unorthodox options (5-way strat switches and such) that I could employ.

    Bottom line, I am asking the experts here at TB for some advice/suggestions on options that I can consider.

    Thanks in advance!

    P.S. I really don't want to change out the stock preamp or the stock MM PUP at this time. I know that Nordstrand and some other folks offer some interesting options for this bass but I don't want to spend a fortune.
  2. First of all, assuming the MM pickup has the standard output for that pickup type, get a Hot Stack so it will balance ok with the MM. The MM will probably still be hotter than the J but the difference will be small. I recently put together a bass for a friend with a SD MM and a standard SD Jazz Stack and I ended up having to put a resistor in series with the MM so it wouldn't swamp the J with both pu's active.

    There are no Volume/Blend stack pots that I know of (a blend pot is already a double pot), so you can either go for a stacked Volume/Volume pot or find out the values of the tone pots (it's active so they'll probably be 100K or less), see if you can find some stack pots of that value, have two of the tone controls in one stack and use the extra hole for a separate blend pot.

    As for the wiring, what I have in my main and backup J/MM basses (Fender Vintage Noiseless Jazz + SD MM Alnico version) is a rotary switch with the following options:

    1 - J wired as stack, MM wired with both coils in parallel
    2 - J wired as stack, MM wired with both coils in series
    3 - J wired with top coil only, MM wired with coil closest to bridge only

    3 is very Jazz Bass and it's hum-cancelling when both pu's are active, but with different pu's it may happen that the MM coil that cancels hum with the top one of the stack is the one closest to the neck, which won't sound as JB as the other one.

    As you can see I didn't include a both-pu's-in-series option. As I said these are already hot pu's and for a higher output, warmer tone, I prefer just the MM wired in series, but of course you could have that option with an extra switch.

    If there's no room for the rotary you could still get 1 and 2 or 1 and 3 with a mini-toggle.

    Note that if you do find a stack pot of the right value for two of the tone controls, you could have one of the switches as a push/pull on the volume control.
  3. ElBajista


    Dec 13, 2005
    Sebring, FL
    If you want to keep all the standard electronics and add a blend knob, think about getting some stacked knobs for the 3band EQ. You have 4 knobs now, so in order to keep those 4 knobs you'd probably have to do something like this: Volume/Blend/Mid/Bass-Treble stacked knob

    When it comes to switching capabilities, I'd add in an "ON-ON" mini-toggle Ser/Par for the J pickup, and and "ON-ON-ON" mini-toggle for Ser/Par/Single Coil on the MM. I'm not sure if the latter is possible on your MM pickup, but I think that would be the best choice when it comes to versatility.