P-Bass Buzz - Bad Coil?

Discussion in 'Pickups & Electronics [BG]' started by fourstringdrums, Apr 14, 2014.

  1. fourstringdrums

    fourstringdrums Decidedly Indecisive Supporting Member

    Oct 20, 2002
    This question is more for curiosity than to remedy the problem since the bass in question will not be mine in a few months once G&L rebuilds it for me.

    I received an LB-100 from G&L and it has had a host of problems. One of which being an excessive amount of buzz from the pickups whenever my hands weren't on the strings. The buzz is also accompanied by a slight "pop" whenever I do touch the strings.

    The local G&L dealer can't find any reason for this to be happening. The shielding is fine and the ground connection and continuity is fine. What I did notice on my own is what happens if I touch the pole pieces. I know that doing this can sometimes produce noise, but this is a weird one: If I touch (with my fingernail) the pole pieces under the D & G strings, I hear a very very faint hum which would be expected. If I touch the middle two poles under the A & E strings, I get the same result. However if I touch the outside poles under the A & E I get an extremely loud buzz that sounds like I just unplugged without turning down the amp.

    Could those two coils be bad or maybe the ground to those two coils doesn't exist? In comparison, my Fender Am. Std. P is dead quiet when I touch the poles.

    Again I'm not keeping this bass, I'm just wondering out of curiosity because it's definitely not normal from my experience.
  2. Were you standing near a neon light fixture? Your body is acting as a partial sink to ground. Does this happen if you are seated on a wood chair with feet off the ground?
  3. fourstringdrums

    fourstringdrums Decidedly Indecisive Supporting Member

    Oct 20, 2002
    I wasn't near a neon light and I only tried it while sitting in an office chair, feet on the ground. Though the buzzing happens here and at the store I brought it to, though the buzz when I touch the poles was only tested here.

    The bass is no longer with me so I can't test it more, but I was still curious.
  4. Audere

    Audere Supporting Member Commercial User

    Apr 7, 2005
    South Beach, OR
    Owner: Audere Audio
    It would have been interesting to measure the resistance from the outside magnets on the E and A strings to the pickup wires.
    It almost sounds like your pickup was wound with too much tension and the insulation failed.
    The insulation failure due to over tension always happens at the end of an coil loop...
    I have seen this multiple times but not on a G&L pickup.

    At the end of this page the pop when you touch a string is discussed http://www.audereaudio.com/FAQ_PUMag_Gnd.htm
    FYI - Most Ps do not have their magnets grounded

    If you had a coil wire insulation failure it would have sounded close to like you are touching the raw end of a guitar cable.
  5. Audere

    Audere Supporting Member Commercial User

    Apr 7, 2005
    South Beach, OR
    Owner: Audere Audio
    I should add that wire winding tension failure is normally a more common problem as the pickup coil gets wider so this should be rare for a standard P.
    And the insulation can "cold flow" across time when the tension is too large and temperature affects the creep rate.
    So G&L might have tested this bass and at that point everything was good as opposed to they shipped a bass with a known problem.
  6. DiabolusInMusic

    DiabolusInMusic Functionless Art is Merely Tolerated Vandalism Supporting Member

    Like I said in your other thread, the buzz is RF interference and is remedied by shielding. The buzz could very well be different in different environments. The fact that it goes away when you touch the strings means one thing, shielding issues. The pop you hear is static electricity being discharged. This will also be remedied by shielding.

    As far as only two magnets making the pickups buzz louder I am not %100 certain on that one but I am going with switched leads. Even then, I personally wouldn't even worry about that issue. It is not like you touch the magnets when you play.
  7. SanDiegoHarry

    SanDiegoHarry Banned Supporting Member

    Feb 28, 2014
    San Diego, CA
    my bass? I 2x check solder joints, bridge ground, shielding.