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Did I screw up installation of the Dimarzio Ultra J?

Discussion in 'Pickups & Electronics [BG]' started by Chrisk-K, Aug 8, 2012.

  1. Chrisk-K


    Jan 20, 2010
    Maryland, USA
    I just installed a set of the DiMarzio Ultra J in my Geddy Lee. All the knobs work, but when I'm not touching a metal part of the bass, it makes electric buzz. Shouldn't the Ultra J be silent?
  2. SGD Lutherie

    SGD Lutherie Banned Commercial User

    Aug 21, 2008
    Bloomfield, NJ
    Owner, SGD Music Products
    They are hum canceling. What you are hearing is electrical field noise. Humbucker cancel magnetic field noise.

    To get rid of that buzzing you need to shield the bass. Also, if the pots are only grounding to the metal control plate, adding a ground bus wire from back of each pot to the jack can often make things quieter.
  3. bassbenj


    Aug 11, 2009
    If the hum goes away when you touch ground it means you have a shielding problem. I presume your Geddy Lee has shielding and in Fenders it's usually conductive paint. So look around for a screw with a solder tab that goes through the conductive paint that grounds it. Make sure it has a wire going to ground (jack body or back of pots)

    If that doesn't fix it or yours has no shielding then a copper foil shield job on cavity and pickup cavities (and wires) is in order. All copper shield must be grounded.

    The kind of hum the DiMarzio cancels does NOT go away when you touch ground. And there should be none or little of that.

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