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Wiring J Bass w/ single volume knob...help!

Discussion in 'Pickups & Electronics [BG]' started by BassistJ, Feb 14, 2004.


  1. BassistJ

    BassistJ

    Mar 20, 2001
    Hemet, CA USA
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    So, yea, thats basically it. Looking to wire my Geddy Lee Jazz with a single volume knob for both pickups. No blend, no tone, just a master volume. My luck finding schematics is almost non-exsistent so I was hoping for some help. Any ideas?
     
  2. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    For what it's worth.

    Can't say as I've ever done it but you should be able to run the hot leads from each pup to the left lug of the pot (looking from top with shaft down) and ground the other pup wires to the top of the pot(assuming two wire pups). Run a ground from the right lug to of the pot to the top of the pot. Center lug goes to hot lug of the jack and Right lug to jack ground (I'm guessing this is a passive bass).

    Or, I've got a Bartolini diagram that shows hot leads from pup going to center lug, the other pup wire going to the right lug and that lug grounded to the pot, left lug going to the jack. Only a single pup diagram and I'm not sure which direction you're supposed to be looking at the pot from in it.

    You're not going to fry anything regardless so see what happens. Just keep the volume down when you fire up. You should get something.
     
  3. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    Also, if you don't get a response you feel comfortable with, call a local guitar repair, I'd think they'd tell you over the phone.
     
  4. You should decide if you want the pickups wired in series or parallel. Series will give a much fatter, warmer, louder, aggressive tone, parallel will sound more like a stock Fender. For parallel, take the hot lead off of the volume pot you no longer want to use, and put it on the same lug as the hot lead on the other volume pot (usually the center, or second lug). For series, take the hot lead off of the volume pot you no longer want to use, and disconnect the ground wire from the other pickup (at its terminus, not at the pickup itself). Solder these two wires together and you should have a humbucker! Go nuts! If this doesn't work, the bass probably has a more sophisticated grounding method than usually encountered in J-Bass cavities, and you should ask a friend or a pro for help.
     
  5. If you're interested in a more aggressive tone and a little more gain and top end, you might consider this approach. Unsolder the pickup leads at their terminus (not at the pickup itself). Remove the original harness (three pots and a jack). The bridge grounding wire is another whole issue, but you'll have to desolder that now (probably at the jack). Store the original harness in case you decide you want to go back to stock (Helpful when you want to sell!). Buy a new 500K audio taper pot (Linear taper will do, also.), a Switchcraft 1/4" jack, and a couple of machine bolts and nuts to plug up the holes in the control plate where the bridge volume and tone pots used to be. Install the new pot and jack in the first and fourth holes. I number the lugs one/two/three, looking at the pot from the bottom, with the lugs pointing down, and numbering them from the left to the right. For series wiring, wire one pickup hot lead to the ground lead from the other pickup. Wire the remaining pickup hot lead to lug one, and run a wire from lug two to the hot (tip) lug on the new jack. Solder the remaining pickup ground wire to the ground (sleeve) lug on the jack, run another wire from lug three of the pot to the ground lug on the jack, and solder them. A lot of folks solder a wire to the back of the pot, and then to lug three (pot) and the ground lug of the jack, but the body of the pot is usually grounded by the metal control plate and this isn't necessary. For parallel wiring, solder both pickup's hot leads to lug one of the pot, both ground leads to the ground lug of the jack. You still need wires from lug two of the pot and lug three of the pot to the hot and ground lugs of the jack, respectively. You can reverse the wires on lugs one and two of the pot, it doesn't matter much especially if you usually run the volume wide open. Try leaving the bridge ground wire off (It is safer not to use your body to shield the system.), but if you can't stand the extra noise, connect it to the jack's ground lug, and be careful! The 500K pot squeezes some more volume and treble out of your pickups, and accentuates any peaks in their frequency response, which may or may not be what you like. The machine bolts give the bass a death metal kind of look. If you don't like that, install a couple of old pots in those holes so you can have something to hold the knobs. I've done this before for guys, and especially with the series wiring, the hotter output causes them to start using the active inputs on their amps. The tone is noticeably different, a lot less polite, so think about that before you try it. Use a 250K pot if you lean toward a vintage tone. Don't feel bad about buying a new jack, because we should be replacing them once in a while anyway. Also, have you thought about dispensing with the volume control and installing an on/off switch? This isn't too hard, and makes the bass more studio friendly by eliminating the "loading" effect. Another configuration would be master volume, a mini switch for series/parallel, and another mini switch to shunt the signal directly from the pickups to the jack. I can get you wiring diagrams for those options if that is what you want.
     
  6. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    That's some good input.
    There are some pro's that just have a jack and run off the amp. I just removed an NTBT onboard from a bass with active Duncan Jazz Lightnin rods (built in preamp), leaving only volume for each pup, then made the NTBT into an outboard preamp. Those pups were considerably louder with much better tone with the NTBT outboard. Don't know if it was the extra battery or what. At some point I'm going to try going right to the jack. You could also throw a second jack in a vacant pot hole and wire the jacks to run true stereo or mono.
     
  7. Putting two jacks in there is a good idea. You could wire a direct signal from the pickups to one jack (to plug into the board), and another signal through the pot(s) to the other jack (for your amp). Good for recording, good for live. There sure are a lot of possibilities with only four holes in the control plate! I guess the trick is to figure out what you are looking for in terms of tone and controls, and then figuring out the neatest way to execute it. On the other end of the spectrum, if you want to strip down, you could get someone to fabricate a new control plate (maybe from the same material as your pickguard) with only two or three holes in it. One volume pot, one jack.
     
  8. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    Hmmm? That is a good idea.
     
  9. SuperDuck

    SuperDuck

    Sep 26, 2000
    Wisconsin
    As my first official moderation of this forum, I am sending this thread to Pickups. It should be honored. :D
     
  10. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    I've run into the same problem with onboard electronics (preamps etc.), doesn't seem to fit in with any forum. Usually I post under amps cause there's some people that frequent that forum with some snap and usually have no problem getting a response that works, as well as a bunch of good options that hadn't even crossed my mind. Don't even remember where this thread was initially posted but it's got some good response. I've tried the pup forum for onboard electronics without much success.
     
  11. luknfur

    luknfur

    Jan 14, 2004
    DIXIE

    I assume you got a plan for good reason but there was a dude with another post that was complaining about not being able to get any volume out of the bridge pup with a PJ setup and single volume. I don't have a bass without either two volumes or a blend so haven't tried it to know if it'd be an across the board problem or specific to an individual setup. Maybe some other folks here have that answer.