Wiring question: Jazz Bass V/B/T + Series/Parallel

Discussion in 'Pickups & Electronics [BG]' started by davekent, Nov 5, 2012.

  1. davekent


    Nov 5, 2012
    Hi all,
    Sorry for asking this.. (probably been asked Nth times)

    I want to convert my V/V/T jazz bass into a V/B/T but with Series/Parallel.


    Does anyone have a diagram for this?
    What pots: 500K or 250k? Log or linear?
    What cap?
    Would I need a 3PDT switch to bypass the blend pot/switch to series or should I use a push/pull pot and a switch?
  2. Stealth


    Feb 5, 2008
    Zagreb, Croatia
    I haven't seen a V/B/T wiring with series/parallel, but it shouldn't be too different from a V/V/T with the same switch.
    I can draw one up later for you. It can be done using one blend pot, one push/pull pot and one regular pot, no extra switches required.
    You'll have to remember to keep the blend centered in series mode, for maximum output, though. I can also make the blend work in series mode, but that'll be fairly complex and I wouldn't recommend it.

    Since you'll have a lot of resistance in parallel at all times, I'd suggest going for 500k-s all the way:
    • M/N 500k (blend taper) for the blend
    • B500K (linear) for the volume
    • A500K (logarithmic) for the tone.

    The cap is up to you, but anything between 22 and 47 nF is the norm, some even like the tone of a 100 nF (0.1 μF) cap. The larger the cap, the lower the roll-off frequency and the thuddier the sound.
  3. davekent


    Nov 5, 2012
    Hi Stealth, thanks for your reply.
    A wiring diagram would be awesome.
    Can you lay it out as V - B - T (p/p)?
    What would you suggest for the cap? Orange .47 or something different?
  4. Stealth


    Feb 5, 2008
    Zagreb, Croatia

    As for the cap, any ceramic capacitor will do. An orange cap is a waste of cash. A .047 μF (47 nF) is a medium value that'll probably work well.

    I've also found a J-bass V-B-T-sw wiring that will require drilling for a switch (a 3PDT), but lets you blend in series as well.

    Edit: and I found my old independent-volumes-in-series wiring that could be reworked into a blend without the need for a switch. Might not be done today.
  5. davekent


    Nov 5, 2012
    If I want to avoid soldering anything to the pot casings, would I have to copper shield the cavities and ground to a common point? Or will the wiring negate this anyway? Sorry for all the questions!
  6. 3515446023_5116d5684f_o.

    Swap the first and second terminals of the volume pot.
  7. Stealth


    Feb 5, 2008
    Zagreb, Croatia
    Yeah, you can copper-shield the cavities and use them as common ground - just remember to ground the output jack's sleeve as well.

    line6man, do you think this wiring would work provided you swap the outer contacts on one of the volumes (treating it as half a blend) and add a regular, coupled volume pot?
  8. jazzyitalian

    jazzyitalian Supporting Member

    Mar 3, 2005
    Minneapolis, MN
    Lawyer and Hobbist Bass Maker
    Great Diagrams!
  9. davekent


    Nov 5, 2012
    Just to clarify.. The block below the blend pot, is that the switch element of the push/pull pot?
  10. Stealth


    Feb 5, 2008
    Zagreb, Croatia
    Yes it is. That can be on any pot, so if you want to make your tone pot the one with the push/pull, you can.
  11. Jbutts88


    Mar 3, 2013
    So when you say swap one and two, which ones do you mean? I put a green on which ones to switch. Is the top or bottom picture correct? Also just curious why you need to switch the two? Thanks


  12. Second image.

    Volume pots tend to sound more consistent throughout their range of control when the wiper terminal varies output impedance, as opposed to providing a variable impedance load on the pickup coils.
  13. Jbutts88


    Mar 3, 2013
    Alright I've got my J Bass all wired up and added copper foil to the project. The good news is it is dead quiet now as far as hum goes. The bad news is something is off with the wiring.

    One pull of the switch as a super bassy sound. The other pull of the switch is much less bassy, almost sounds wimpy. I guess the more bassy is series?

    Anyways.. when the switch is on the bassy sound it works perfect, the blend is bypassed and the volume/tone works.

    When the switch is in the wimpier sound the v/t work but the blend cuts off the entire volume when rolled off.

    Here's how I wired it basically looking at the plate unscrewed and flipped upside down. I had to arrange them this way to fit. They are model J pickups with the black and white of each pickup soldered and taped off.

    Any ideas what I did wrong?

    Thanks a ton

    Attached Files:

    • jb.
      File size:
      30.2 KB
  14. Jbutts88


    Mar 3, 2013
  15. Rip Topaz

    Rip Topaz

    Aug 12, 2005
    Willow Street, PA
    Beta tester for Positive Grid
    Sub'd so I can find this again. About to do this mod to my J.
  16. ditto
  17. Cadfael


    Jan 4, 2013
    Germany, EU
    I have three different "V/B/T series parallel" JB wirings in my compilation (2.1.22-24) ...

    2.1.22) P/P: Balance has influence in serial
    2.1.23) 3x2 switch: Balance has no influence in serial
    2.1.24) S-1 switch: Balance has no influence in serial

    It is very hard / impossible to find a Fender JB-know S-1 nowadays. For people who want to install Strat knows or Tele Dome Speed knobs, it is easyer to find the right S-1 switch (knobs).
  18. Jbutts88


    Mar 3, 2013
    Incredible. Thanks a lot man, just wish it was in English. It looks like 2.1.23 is what I need. Thanks again
  19. michaelandrew

    michaelandrew The bass player is always right.

    I want to do this mod on a Squier VM J - I just have a question about the pots: I always thought volume pots were audio (logarithmic) taper and tone pots were linear taper. Stealth has suggested audio taper for the tone and linear for volume. What difference does this make when playing?

    BTW - Thanks to Stealth for the excellent diagrams and info. Newark is a good source for Bourns pots ($8 shipping to Canada :)).
  20. Cadfael


    Jan 4, 2013
    Germany, EU
    95% of all tone pots are audio pots ...
    4% might be linear pots, built in in old European and Asian basses from the 1960s and early 1970s.

    Some confusion comes by the fact that pot declaration (printings) may vary form country / continent to country / continent ...