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A 3th jazz bass pickup

Discussion in 'Luthier's Corner' started by Pellepop, Jan 23, 2012.


  1. Pellepop

    Pellepop

    Jun 10, 2010
    Sweden
    Hi
    I´m getting near the end of building a jazz. When test playing I started to wondering bout why there´s no 3 pickup in the neck position. So I made a simple set up with an old extra jazz pickup, sliding it up and down the body to se what would happend. My goal was to achive a bit more deep sound. It turned out that it did add something extra but it seem to be very hard to find the exact best position, one mm to the left or right change the sound.
    Sliding it very much together with the bridge pu created a flanging sound! I guess that would be the resonas frequensy changing?
    So my question is. Has anybody else tried this? Any result to or idees to share?[​IMG]
     
  2. Coolhandjjl

    Coolhandjjl Supporting Member

    Oct 13, 2010
    Appleton
    The Rickenbacker 4004L, AKA the Lemmy Kilmister Edition, has three pups. Where is goes is a bit of voodoo. Ric puts theirs right up to the fretboard simply cover up the truss rod access (in the event you have to remove the rod). Remember, the 'growl' comes from comb filtering, (phase cancellation) of the pickups interaction with each other when two or more are on, meaning placement is pretty subjective.
     
  3. Stealth

    Stealth

    Feb 5, 2008
    Zagreb, Croatia
    Brilliant jig. This is how it's done. :D

    That said, Coolhandjjl is perfectly right, three pickups cause more cancellation than two - and there's another effect as well.
    The more pickups you have, and the more volume controls you have, the muddier and darker the overall tone will be. The volume controls will all be in parallel and, if all tone controls are, say, 500K, that will load the pickups with only 1/3rd of that. The solution is to use higher value pots as volumes (say, 1M, which brings the total to 333K which is should be enough to prevent muddiness) or to only have two pickups active at any given time.
     
  4. Pellepop

    Pellepop

    Jun 10, 2010
    Sweden
    Aha so in this case a simple zero gain pre amp would be good ide?
     
  5. iiipopes

    iiipopes

    May 4, 2009
    A zero gain preamp would buffer the output, but you still have the impedance drop/comb filtering problems of the pickups going into the front end of the preamp.

    What I do is to put a .01 mfd capacitor inline between the bridge pickup and its volume control on a jazz-style bass. This cuts the lows (there isn't that much low end on a bridge pickup, anyway) on the bridge pickup and cleans up the signal, getting rid of some of the comb filtering on the low end when the mid pickup is added.

    If you add a neck pickup, try the capacitor as described to the brdige pickup.
     
  6. The flanging could maybe be caused by the magnetic fields because the pickups are not reverse-phased? Did you try reversing the pickup that you put in the middle?
     
  7. Ric5

    Ric5 Supporting Member Commercial User

    Jan 29, 2008
    Colorado
    I convert 4 string Rickenbackers to 5 string basses.
    For years I have tought about doing a bass like the strat-o-caster guitar. 3 pickups and the middle one reverse wound and then employ the 5 way switch.
     
  8. Ric5

    Ric5 Supporting Member Commercial User

    Jan 29, 2008
    Colorado
    I convert 4 string Rickenbackers to 5 string basses.
    The flanging effect could be one magnet pulling up and the others pulling down.
     
  9. Ric5

    Ric5 Supporting Member Commercial User

    Jan 29, 2008
    Colorado
    I convert 4 string Rickenbackers to 5 string basses.
    sdpu-2.
     
  10. Stealth

    Stealth

    Feb 5, 2008
    Zagreb, Croatia
    Ric5: That's my goal as soon as I scrounge enough cash for a Jazz bass copy, though I'd rather make one with 70s J spacing and a P in the middle of them, rather than a PJ and an additional neck pick-up.

    As for the Strat Bass, I recall a build where someone initially made one with just a neck SCPB and two fake wooden pickups, but had a change of heart at the last moment and made the whole shebang.
     
  11. Son of Magni

    Son of Magni

    May 10, 2005
    NH
    Builder: ThorBass
    I've built a few JJJ basses. I used Barts with a Bart preamp. I either hardwire two of the pups in parallel or make it switchable as J-JJ or JJ-J (if you get what I mean). This way they can be fed into the Bart stereo preamp. I love the sound and versatility. I push the bridge pup towards the bridge.
     
  12. king rew

    king rew

    Feb 18, 2009
    Maine
  13. pilotjones

    pilotjones Supporting Member

    Nov 8, 2001
    US-NY-NYC
    The flange effect as you sweep the position of one of a pair of pups is an entirely natural result of the shifting comb filter produced, and has nothing to do with magnetic interactions between pickups. If you know what to listen for, you hear it all the time on talk shows as guests move their bodies and the distance between host and guest lavalier mics changes.
     
  14. psychotiger

    psychotiger

    Feb 24, 2008
    Austin, Texas
    Builder: Moore Custom Guitars
    Would you post or PM to me a wiring diagram for that switchable set up? Thanks for the idea!
     
  15. Stealth

    Stealth

    Feb 5, 2008
    Zagreb, Croatia
    Here's my idea for a JPJ wiring.

    JPJ-1.

    Upper switch position is a Jazz bass. Middle switch position is a J-P-J. Lower switch position is a P-J. Probably a good idea to up the pots to 500K each. Obviously, the same applies for a JJJ bass.

    Son of Magni, I agree with psychotiger, please post your wiring. I'm not sure if I'm right about it being deceptively simple and using only an SPDT on-on-on or half a DPDT with three positions (middle pickup to center lug, neck pickup and one preamp input to top lug, bridge pickup and other preamp input to bottom lug).
     
  16. Son of Magni

    Son of Magni

    May 10, 2005
    NH
    Builder: ThorBass
    Stealth, the DPDT as you designed would work perfectly. Then for extra fun, you can take the bridge pup and wire through a two position dpdt to do phase inversion :eek:
     
  17. iiipopes

    iiipopes

    May 4, 2009
    Something very similar was done in the late '80's and early '90's with the original Fender Stu Hamm 32-inch scale "Urge" bass.
     
  18. Stealth

    Stealth

    Feb 5, 2008
    Zagreb, Croatia
    Have you actually tried a phase inversion on a bass? I haven't; a lot of people say it's not worth the effort - did your mileage vary?

    Yes, except Stu Hamm's bass is active, and the control layout was something really weird as seen in the official diagram.

    From what I can tell, first there's a Jazz pickup blend combined with a switch that either picks Jazzes only (with a variable blend between the two), adds the Precision at full volume or picks the Precision only. Then the whole shebang goes into the three-band preamp with an active master volume. Trouble is, there's no telling what preamp's in there - it's neither a Jazz Special nor a Precision Elite because none of them is a three-band (the first is a two-band, I think, and the other is just a buffer).
     
  19. Jools4001

    Jools4001 Supporting Member

    Clover does it..gives me GAS anyway

    clover_avenger5_cb01.
     
  20. Son of Magni

    Son of Magni

    May 10, 2005
    NH
    Builder: ThorBass
    Iirc, the old Les Paul Triumph has it. A "few" years ago I added a second set of P pickups to my fretless Precision bass. I put a phase switch in and it was great. So yes I've done it on other basses as well. The key is to have a blend control or separate volumes. You want to turn down the inverted pickup so it doesn't cancel too much. Gives a funky hollow kind of sound.
     

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