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Series/Parallel on J bass... Why didn't I do this before???

Discussion in 'Pickups & Electronics [BG]' started by vindibona1, May 20, 2020.

  1. After a some studying wiring diagrams, selecting and receiving a push-pull pot I finally got the series/parallel wiring wired up on my J Bass yesterday. I always like this bass, especially with the Aguilar AG 4J-HC pickups. And while a good sounding bass, there were times when I wanted it to have more cojones in the sound. I think that is the draw of the P bass.

    Having never owned P Bass I can't tell you how close the sound is with the series wiring, but it's deeper, for sure in series mode. But with the switch I didn't lose anything in parallell either. The parallel wiring sounds the same as it did before, with some brighter crisper sounds, but sometimes a bit too bright with the tone all the way up. The series adds volume and thickness and has just enough brightness with the tone at 100%. This new wiring gives me a 4th gear in tonal pallette selections, almost as if it were active. While I really haven't had the desire to bring my Jazz 4 out to play and relied on my 5's, it will get some serious consideration (if gigs ever open up again).

    With such a simple mod, why don't more folks do it??? I can't believe I hadn't done it long ago.
    Last edited: May 20, 2020
  2. bigtone23


    Dec 10, 2014
    Denver, CO
    Well, now you have done it. Welcome!

    Series/parallel is on most of my J type/2 pickup basses--hidden via a push/pull pot. I may not use it much, but it nice when I do!

    This may be the most common mod done to J basses owned by P-centric bassists who miss that thicker tone.
  3. BLDavis

    BLDavis Master of Snarks. Supporting Member

    May 21, 2009
    Ellenboro, NC
    I'm a recent convert myself and definitely like the extra tonal variation. It makes an already versatile instrument even more so.
    Dennis Davis, SactoBass and bigtone23 like this.
  4. jgroh


    Sep 14, 2007
    If you dont mind, can you explain how you did the mod? I had a 60th Anniversary Fender J with the SB1 switch, and even though it appears alot of people didnt love the option, I did. Sold that bass a while ago. Now, I have a G&L Jazz now and would love to have a series option, but I havent found anything that explains how to do it. Just some diagrams that were Greek to me.
    Winslow likes this.
  5. @jgroh Below find 3 diagrams for wiring. I recommend the Mojotone/CTS pots. I initially had an Emerson pot which broke before I even got to soldering it. The CTS wiring in gray is the scheme that Mojotone sent me (wires represented in gray), but if you want your bass to be in standard parallel mode, use the drawing (wires in red). The CTS pots have a better, more substantial build than the Emerson I had. I recommend the CTS. I got mine from Musicians Friend. Sweetwater is out of stock on them. You can buy them direct from Mojotone too, but probably will be charged shipping.

    I did it the first way from Mojotone and I think I like it that way (in Series), so I'll leave it that way for now. The other was courtesy of advice @alanloomis1980. So if you want your bass to remain as is, in parallel, then do wire it as marked in red. The difference is that 1-3 and 2-4 are reversed (according to Alan). I haven't tried it, so hopefully 1, C1 and C2 are supposed remain the same. Alan? Also you will see that Mojotone has a capacitor/resistor combo in both volume pots. I've done this in Stratocasters to preserve trebles when rolling off the volume, but I didn't see it necessary for this bass wiring project.

  6. bigtone23


    Dec 10, 2014
    Denver, CO
    Those diagrams are correct.
    Generally speaking, based on tonal propensities, P bass guys may tend to wire their J basses to be in series with the pull up for parallel, J bass guys tend to do the opposite. haha.
    Treble bleed networks are handy, but I find I like them more on guitars vs basses.
    Last edited: May 21, 2020
  7. That’ll do it!
  8. One more thing... I've got an Audere ProZ (4 band) preamp in my Jazz 5. It's pretty versatile and I think can get a similar series sound with the Z switch in the up-most position.
  9. bigtone23


    Dec 10, 2014
    Denver, CO
    This is true. I have found (especially live-where critical tonal things are not so critical) that EQ tweaks have a successful end result, like wiring tweaks. Boost some low mids and lows, roll off a touch of highs and now my parallel pickups on my J (or Tele, Strat, P90 Les Paul or Bass VI) sounds like series.
    Dennis Davis likes this.
  10. Jefenator


    Aug 22, 2008
    If I ever redo the harness on my J you're making me want to try that. (Except my J sounds pretty sublime right now as is - in parallel.)
    My Dingwall Afterburner comes rigged for series/parallel right from the factory. Definitely one of the more musically useful passive options I've ever encountered.
  11. fretlessman71

    fretlessman71 How ya doin', Texas? Supporting Member

    I have a fretless "Double P" bass with this wiring mod, and I am TOTALLY sold. Eventually all of my passive 2-pup basses will have this I think. I wonder if this would be an issue with a P-J config? You know, one "humbucker" and one single coil?
  12. Killing Floor

    Killing Floor Supporting Member

    Feb 7, 2020
    Austin, TX
    I’m in that opposite camp in that I prefer P necks so I’ve used preamps to mod Ps to a J tone. But it’s cool to have options like this and thanks for sharing. I think you can come pretty close with the EBMM or G&L electronics. But yeah, this is a great and harmless and simple way to mod a J. Like it.
  13. sotua


    Sep 20, 2004
    Somewhere in time
    I do a rotary for neck - series - parallel - bridge. I run series most of the time. It's soooo good how that mid hump comes up, particularly for picked aggressive rock.
    filwitheneff likes this.
  14. Winslow


    Sep 25, 2011
    Group "W" Bench
    This is interesting, and seriously tempting. Gonna have to bear this in mind if I ever decide to swap out pickups on my J. :thumbsup:
  15. murphy


    May 5, 2004
    Toronto, Canada
    I had it in my Jazz 5ver...thought it would be great in my Reggae band ...But found I still preferred the parallel with Neck pickup full and bridge backed off 20 percent
    so I removed it
  16. selowitch

    selowitch Supporting Member

    Aug 6, 2005
    Rockville MD
    It’s a great mod.
  17. negativeions24

    negativeions24 Supporting Member

    Nov 20, 2010
    SBA County, CA
    Just wired my Jazz with the DPDT diagram reversed so the bass default setting (down) is series and pull is parallel. As a Precision player first and foremost, this is glorious...I'll be playing my Jazz more often now :thumbsup:
    Dennis Davis likes this.
  18. DoctorZee

    DoctorZee Supporting Member

    Jan 27, 2018
    New York / New Jersey
    The first thing I’m planning to do when things get back to normal is head to my tech to have this done. I wish I trusted myself to DIY it, but I don’t.
  19. Inara

    Inara Fierce Fun Fretless Female Supporting Member

    Jun 12, 2017
    Seattle, WA USA
    I'm a P Bass girl, and I definitely prefer the default to be series on a Jazz lol.
    Dennis Davis and negativeions24 like this.
  20. And that's what I ended up with... Down=Series... and I like it. My question to you is- how close is that sound to a P Bass? I've never had the opportunity to play a good quality P Bass but can understand the sound that P players are going after.
    Dennis Davis likes this.

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