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J-Bass Hum

Discussion in 'Hardware, Setup & Repair [BG]' started by madskillz, May 21, 2003.

  1. madskillz


    Sep 20, 2002
    I noticed that the J-Bass I have ( MIA) has a hum that comes through the amp when either one of the pickup are turned to less than full, with the tone control set to full. The hum will go away, if I turn one or both volume controls to full on, or turn the tone control off. Does anyone have an experience with this problem? I have a SWR WM 12 and it does not have the problem with a P-Bass I have. Checked to make sure no outside interference is the cause. Thanks.
  2. Ben Mishler

    Ben Mishler

    Jan 22, 2003
    San Jose
    That is perfectly normal for Jazz bass pickups. I believe it is called 60 cylce hum. That comes with the territory of the single coil pickups.
  3. madskillz


    Sep 20, 2002
    thanks. I assume the cure is turn the controls till you don't hear it or buy different pick-ups. It seems you lose some tone possibilites when you have to avoid certain settings.
  4. rllefebv


    Oct 17, 2000
    Newberg, Oregon
    Unless it's very extreme, this is really only a problem when the music stops... You could shield the control cavity with copper tape and/or conductive paint... Connect the ground wire from the bridge to the shielding. Also, some J's are wired without a ground wire connecting to the ground lug of the output jack... Worth checking out...

    My '78 Musicmaster, the muttha of the 60 cycle hum, quieted way down after shielding... My J bass isn't bad enough for me to shield it yet... well that and I have too many projects going just now :)

  5. Turock

    Turock Supporting Member

    Apr 30, 2000
    Turn the other one "less than full" to match the first one and it will go away. Both pickups just need to be set at the same volume, not necessarily full.
  6. jani_bjorklund


    May 22, 2002
    This is compleatly true. That's why I decided to take out the other volume. I now only have one volume for both pickups. Instead I threw in a DPDT switch for series/paralel where the second pot was sited. Now everything is just beautiful.
  7. rllefebv


    Oct 17, 2000
    Newberg, Oregon
    Definitely sacrificing some killer 'blended' settings by always having the pickup at the same volume... Also losing that awesome 'solo' bridge pickup sound.

    Again, live, while the music's playing, you're not gonna hear it... There're steps you can take without limiting your tonal pallette...

  8. Turock

    Turock Supporting Member

    Apr 30, 2000
    I think you misunderstand the purpose of my post.
  9. bigdaddy-05


    Aug 17, 2001
    Los Angeles
    I have the same exact problem! I have a J-bass with Dimarzio J's which are humbucking. The bass use to be dead quiet if I would take my hands off the strings, but now there is a nasty hum? HOWEVER, if I turn the tone knob all the way down/ off the hum entirely disappears. Turn up the tone knobs and it's back.
    It's not the amp SWR WM12.
    It's not the cord. (Monster, this is how I discovered the problem seeing if I could tell the difference between different cords on different basses)
    If I plug in a different bass there is not a problem so it's not lights, outlet, etc.
    The bass is shielded and Dimarzio is no help?

    I appreciate all your imput. Thanks! :cool:
  10. Nick Gann

    Nick Gann Talkbass' Tubist in Residence

    Mar 24, 2002
    Silver Spring, MD
    If it stops when you take your hands off the strings, then it is a wiring/grounding problem.
  11. poppamies


    Dec 15, 2002
    No. It's not a grounding problem. Just the opposite. That's exactly the purpouse of grounding the bridge. To silence any possible hum left.
    If nothing is been changed in the guitar wiring and the hum suddenly appears it's probably has to do with the power wiring in the house/rehersal studio. Bad grounding, if any at all. Also if your amp is connected (line out) to a mixer without a DI box this might also cause hum, ground loops.

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