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Grounding Issue ?

Discussion in 'Pickups & Electronics [BG]' started by erikmilan1987, Mar 24, 2010.


  1. erikmilan1987

    erikmilan1987

    Feb 1, 2010
    Hi, i have a single coil Jazz Bass thats having a grounding issue; Im running both pickups full and when im toughing the string it removes certain amount of the natural noise that remains even with both pickups full... is this a normal behavior ?

    I have checked every ground connection and everything works fine (Including Bridge ground), also i have shielded my control cavity with copper tape and the pickups cavities are grounded with a thin copper plate on the bottom.
     
  2. bassbenj

    bassbenj

    Aug 11, 2009
    The rule is that if the noise level changes (becomes less) when you touch the strings then it's a shielding/grounding issue.

    So you have to look for places where shielding is missing or the copper is not grounded. From your description you might try adding copper to the sides of the pickup cavities and another possibility is grounding the magnets on the pickups (run a strip of the copper tape (conductive glue) down the bottom of the magnets and ground it. And since shielding can never be perfect (tops of pickups have to be open) the hum and noise really is never totally gone if you crank gain or a room has a lot of electrical noise going. And be sure all your copper foil is really grounded including the foil on the "lids" of the cavities like the pickguard and knob plate.

    The usual hum in a Jazz is the single coil noise which should go away when both pickups are on at the same level. But that kind of hum won't change when you touch the strings or other ground.
     
  3. erikmilan1987

    erikmilan1987

    Feb 1, 2010
    Ok i checked every spot on my control cavity shielding... all its showing good signs of continuity with very low ohm reading and also i have 0 volts running on my shield...

    Ground connections shows continuity in every spot that should have it (bridge, plate, shield, pots, jack).

    So still i dont know whats going on... i can reinforce the shielding in the pickup cavity with aluminum EMI tape would that ease the issue ?

    Im also considering that a damaged pot could be the issue.
     
  4. SamanthaCay

    SamanthaCay Like bass guitar OMG!

    Nov 16, 2008
    Denver, CO.
    Have you considered all the other variables like your amp, amp settings, effects, cables as well as the room your in? gui**** center or any other music store is a good place to test this theory.
     
  5. erikmilan1987

    erikmilan1987

    Feb 1, 2010
    Firts i was on my band studio and heard the issue on the studio amp... i thought that it was that the outlet was not grounded or some issue with that amp... later i arrived to my house and tested with my amp and also swaped cables etc... the problems stills there.

    My strat dosent have this issue, it has humbucking strat pickups has opposed to my jazz bass with single coils but im running the jazz with both pickups full and im getting certain noise that goes away when im touching the strings
     
  6. bassbenj

    bassbenj

    Aug 11, 2009
    This is a mystery. Everything seems to be right. It's a long shot but you might try a different cable under the idea that the noise is not getting into the bass but is getting into the cable somehow.

    Just on the chance it may be a humbucker issue try varying the volume controls of the two pickups. If the humbucking is right, hum should increase as you go to a single pickup. (either one) And the true test for humbucker hum is to move the bass around in all manner of weird orientations to see if you can find a spot where the hum "nulls" out. (gets less) If you can find such an orientation it may mean that your pickups are alike and are not bucking hum. One should be reverse-wound with reversed magnets from the other. If they are identical they won't cancel hum!

    There is a slight possibility that the noise is from radio frequencies. I presume the bass is passive so that shouldn't be it. But it could get into the amp so trying a different amp is a good test too.

    I don't know. You've got a puzzle there!
     
  7. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
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