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Split-Jazz Bass Style Pickups: Questions

Discussion in 'Pickups & Electronics [BG]' started by Precisionb87, Jan 13, 2012.

  1. Hello
    I have decided to try and make my own split-jazz bass style pickups (ala lindy fralin...) . I have wound a couple single-coil guitar pickups in the past, and it seemed to work out fine.

    I ordered the Jazz Bass pickup kit from StewMac. I plan on carefully cutting the flatwork exactly in half, and then going from there. So here are my questions:

    1. Are the two coils wired in series or parallel?
    If both options are viable, what are the tonal differentiations?
    (how does Lindy Fralin do it?)
    2. Approximately how many turns/impedance should each coil get?

    I am assuming that the topology of these pickups are pretty much the same as a P-bass style pickup. Is that correct? :help:

    Thank you for any insight.
  2. Split coils are almost always wired in series, as the output and output impedance is way too low when you put two "half pickups" in parallel.

    How much wire to wind with is personal preference. Some like overwound pickups, others like underwound pickups.

    Split coil J pickups are very different from P pickups. The aperture is narrower, and the coil is generally taller.
  3. Yes, I know they differ from p-bass pickups physically, I guess what I meant was magnet polarity and winding direction. Does anybody have a ballpark idea of what the coils wind turns # should be? Half that of a single coil?
  4. SGD Lutherie

    SGD Lutherie Banned Commercial User

    Aug 21, 2008
    Bloomfield, NJ
    Owner, SGD Music Products
    Magnet polarity would be opposite for each half. You can wind the two coils in the opposite direction. But you can also wind them int he same direction and just wire them up opposite. Both ways work the same.
  5. Well, thanks for the input so far. I have begun the bridge pickup. Here are some pictures of what I have so far, I will post more as I progress. (feel free to offer any more advice)
  6. Well, I wound the pickups with some 42 awg wire. I wasn't really sure how many turns to do, so I wound each about 8000 turns. (I guess I can always remove turns if I need to.)
  7. Well I got the bridge pickup potted, magnitized, and wired up. Here are some pictures.
    Double boiler with "Gulf Wax" (Paraffin):

    Magnetization process. (from stewmac):

    Wired up (I just copied the exact way a precision pickup would be wired):

    Sound clips coming soon (hopefully). If it sounds crappy, I'll let you know.
  8. PBfanNO1


    Jan 26, 2012
    You are The Man PBASS!:bassist:
  9. kraigo


    Jun 21, 2007
    Minneapolis, MN
    I'm looking forward to hearing your completed work. Good job!

  10. Well I installed the pickup, and much to my surprise, it doesn't sound half bad. BUT there are a couple issues...

    The tone of the pickup is fair. The issue I have with it is it seems to be a little on the darker side. (I guess about how a 10% over wound would sound. Just take some windings off right?

    I would, but the output seems to only be about 80% a single-coil counterpart...

    What do you think the issue(s) may be?
    I have read that a standard P-bass pickup has a total of 10,000 windings. Mine has about 16,000, so why the weak output?
    I am positive that its not a phase issue.

    Here is what I suspect:
    The Alnico magnets have still not reached their full charge, and that is why the output is slightly lower. I suspect that if they where in fact fully charged the output would be tremendously more than that of a standard single-coil.

    I guess what I'll do is take the pickup out and try the magnetization process over again.
    Your thoughts?
  11. P.S.
    The hum canceling aspect of the pickup is awesome. It's dead silent :)
  12. SGD Lutherie

    SGD Lutherie Banned Commercial User

    Aug 21, 2008
    Bloomfield, NJ
    Owner, SGD Music Products
    P basses are 10,000 turns per coil, not total!

    Phase wont matter since the strings are not being sensed by both coils. It only matters for hum canceling.

    What is the resistance of your pickup?

    I think that might be it. It looks like you have more than enough wire on it.
  13. each coil is measuring about 3.5k ohms. Do you think that's too little? I could add some more wire.

    oh, and thanks on the heads-up about the P-bass pickups. That explains a lot. Do you know what some of the split jazz bass pickups measure?
  14. SGD Lutherie

    SGD Lutherie Banned Commercial User

    Aug 21, 2008
    Bloomfield, NJ
    Owner, SGD Music Products
    I haven't had too many split Jazz pickups to check out. We can look at some of the DiMararzio pickups; the Area J's bridge pickup is 7.80 Kohm, the Ultra Jazz is 12.3 Kohm, the Model J is 6.82 Kohm. The Ultra Jazz might be wound with 43 gauge wire which would give it a higher resistance, and more midrange.

    My notes on the Nordstrand nj4sv says it's about 7.85k for the bridge pickup.

    So you are pretty much in that range of pickups.

    The conundrum with pickups is if you want it brighter, you generally sacrifice output. The hotter you wind it, the darker they get. However, there is a range where the resonant peak gets lowered into the upper midrange, and that actually makes the pickup sound brighter. It tales some experimenting to get what you are after.

    You should try the pickup with the two coils wired in parallel and see what it sounds like.

    When you were charging your magnets, make sure the vice jaws are closed so that they are pretty much touching the pickup's magnets on both sides. If you leave a gap they wont get as full a charge.

    I don't use alnico's much, except for pickup repairs, but I do it this way:


    Normally I would stack two magnets on each side. I'm starting to use alnico rod magnets now (hint, new products coming ;) ), so I need some larger charging magnets.
  15. knarleybass

    knarleybass Commercial User

    Apr 6, 2005
    Tustin, CA
    Owner of Ulyate Instruments
    no sound clips???

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