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Humming '63 Jazz Bass

Discussion in 'Luthier's Corner' started by Jacques Le Dick, Mar 22, 2005.


  1. Jacques Le Dick

    Jacques Le Dick

    Mar 22, 2005
    Hello there Guit.Tech friends,
    *
    Can someone help me out with a humming Jazz Bass(lindy fralin pickups)?
    The problem is that the bass starts humming when backing off one of the two volume pots? Is there a solutoin to solve this problem?
    *
    Greez,
    *
    Jacques Le Dick.
     
  2. r379

    r379

    Jul 28, 2004
    Dallas, Texas
    Yes. Leave both volumes full on or get hum-canceling pickups. Jazz pickups are single coils so they will hum. The two pickups are reverse wound so they hum-cancel when set for equal volume. If you don't want to change pickups you can (to some degree) change the pickup heights to vary your tone while leaving both volumes on full. Hope that helps.
     
  3. lethargytartare

    lethargytartare

    Sep 7, 2004
    Chicago
    Follow the mods on this page:

    http://www.guitarnuts.com/wiring/shielding/shield3.php

    The shielding and grounding scheme this guy maps out is fantastic, and is now the first thing I do to every instrument that enters my house. Works every time -- I have a S-S-S strat clone wired this way, and I get no hum from it even when I hold it inches away from the flourescent lights, or monitor in my basement (well, when I get INCHES away there's probably something slightly detectible, but you get the idea). Plus there's an anti-shock part to it too...So all of my guitars and all my basses (including my Jazz basses and an active Schecter bass) are star-grounded in this manner, and I've become a big flag-waver for it.

    A lot of people on those forums get really focused on the PRECISE cap that is recommended -- but in the intro page he mentions the alternatives you can use. I think I'm using a 630v cap in mine...

    I've even rewired a guitar using tin foil as the shielding material, and it made the guitar absolutely hum free. Nice and cheap solution!

    Good luck!

    ltt
     
  4. Jacques Le Dick

    Jacques Le Dick

    Mar 22, 2005
    I don't think it is a sielding problem.(I shielded every wire, and painted de inside of the guitar with stewmac's shielding paint)
    Normally the two volume pots are on 10 but for some songs I like to back off the volume of the bridge pickup,just a little bit (9). When I do that the bass starts humming.
    I'm aware of the single coil pickup problem (with humbuckers it would be ok). But I like the sound of these pickups(rewound by lindy fralin).
    I guess I have to deal with it and leave the volumes full open,but why did fender put two volume pots in then?

    yooooooo,

    Le dick. :confused:
     
  5. lethargytartare

    lethargytartare

    Sep 7, 2004
    Chicago
    Humming isn't a single-coil pickup problem -- it's a grounding problem (it's a myth that single coils are just noisy and that you just have to deal with it). Shielding cavities helps, but doesn't resolve the problem. A better grounding scheme insures that noise is shunted to ground, and doesn't get into the signal. The other problem with stock wiring schemes is that they typically are susceptible to ground loops. I don't fully understand the science here, but basically you create paths where noise that should be shunted to ground is actually able to recirculate and create more noise. That link I posted has detailed explanations of all this (much better than I can give). But suffice it to say that just shielding the cavities is not necessarily enough.

    I've never been a fan of the two volume setup either. I always put a blend in place of the second volume whenever I get a bass like that. Won't solve your noise problem, but is a relatively easy mod to make managing tone easier. Check it out here:

    http://guitarelectronics.zoovy.com/product/WDUSS2102

    I really suggest you consider the QTB mods! I think you'll be pleasantly surprised.

    Cheers!

    ltt
     
  6. gyancey

    gyancey

    Mar 25, 2002
    Austin, TX
    Alternating currents generate two types of fields: electric and magnetic. Non-ferrous shielding only drains away electric field interference (RF, computer monitors, etc. aka "noise"). Magnetic field interference (power transformers, AC wiring, etc. aka "the hum") can only be cancelled out via coils wound in opposite directions. Turning down one of the volumes on your bass effectively reduces the gain of one of the coils, thus the hum.
     
  7. lethargytartare

    lethargytartare

    Sep 7, 2004
    Chicago
    Is that magnetic field interference the 60 cycle hum people talk about?

    BTW, off topic -- how's Opposite Day?? I saw you guys open for The Real Heroes at the Flamingo Cantina in 2003 (was visiting, I live up near Chicago), and got hooked on what you guys were doing -- fantastic music! Then saw your basses and was just blown away...amazing stuff! Keep up all the great works!!

    Cheers!

    ltt
     
  8. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    FWIW:

    as gyancey said, hum is inherent in the design of singles. Some are worse than others and of course less than optimal grounding will enhance the issue.

    Some guys swear by shielding including Sadowsky but he will also be the first to warn you that copper shielding creates great opportunties for potential shorts. I couldn't tell any difference from using copper shielding with a variety of pups and after the third bass I stopped bothering with it - but it looks very professional. I never shielded a pup bay. Grounding plates may help some if your bass doesn't have them. Also I had a Duncan hot P once that hummed and for whatever reason, after dipping it it knocked it out and nothing else did.

    I've had over 50 sets of pups and a set of Duncan classic stacks I had put out an excellent vintage Fender J tone (definetly more preferable than Fralins and Antiquity II's I've had). They're 4 wire w/ground HB's so you have a number of additional wiring options available beyond singles. The main thing was the tone and they were dead quiet no matter where you the volume controls - and I prefer two volumes over a blend cause it gives you more tone control. Fender noiseless pups seem to be very popular but never had a set of those to know the tone.
     
  9. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    FWIW:

    forgot to mention that single coil hum for the most part is not an issue cause you simply adjust technique to maintain contact with the strings whick kills 90% of it so it's not noticeable during play. You just don't set the bass in a stand without turning the amp or volume off or using standby.
     
  10. lethargytartare

    lethargytartare

    Sep 7, 2004
    Chicago
    Or rewire it and /never/ worry about it :D