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Discussion in 'Luthier's Corner' started by asnutter, Apr 10, 2006.

  1. asnutter


    May 11, 2005
    Southwestern PA
    I have recently purchased a set of Dimarzio model j, jazz bass pickups, and wonder if shielding is necessary???

    First off, let me say that I have searched the posts for shielding and have found a great amount of conflicting information...

    I plan on installing these pickups with a traditional j bass vol+vol+tone control plate and pots...

    I have seen the schematics and have a hard time understanding the grounding deal...

    If the bridge is grounded, do you still need the shielding???

    I have read Hyscock's book on electrickery, but have a difficult time assimilating his excellent info for bass...

  2. Rodent

    Rodent A Killer Pickup Line™ Commercial User

    Dec 20, 2004
    Upper Left Corner (Seattle)
    Player-Builder-Founder: Honey Badger Pickups & Regenerate Guitar Works
    A -

    you'll probably get a larger response to this question in the Pickups & Electronics forum...

    but my rule of shielding: copper foil for the entire control cavity and back of the cover plate, copper foil or shielding paint for the pickup cavities (and any other cavity with electrical/electronics in it), copper foil underneath the bridge with a ground lead soldered to it, star grounding for everything in the main cavity, and a ground lead from all cavities connected to the star grounding plus the copper foin in the main control cavity. you can never have too much shielding

    there is a great thread on star grounding in the P&E forum worth searching for if it isn't maintained as a sticky

    all the best,

  3. ehque


    Jan 8, 2006
    the bridge is metal, why would you need a copper foil under the bridge? i bet it messes with the bridge-wood vibration coupling more than the benefits it provides...
  4. Rodent

    Rodent A Killer Pickup Line™ Commercial User

    Dec 20, 2004
    Upper Left Corner (Seattle)
    Player-Builder-Founder: Honey Badger Pickups & Regenerate Guitar Works
    copper under the bridge - it's all about a good ground contact, and one that will remain there over time.

    as for sonic differences, if it's messing with anything it's happening in a good way according to the guys who are using basses I've modded/built.

    but to each his/her own on the merit of this, ya know

    all the best,

  5. Do you have to ground to the bridge? I mean can you ground to something else?

  6. Trevorus


    Oct 18, 2002
    Urbana, IL
    Grounding the bridge just connects the strings to ground, which is actually grounded at the jack. Active pickups usually don't want you to ground the strings. But if you are running passive, connect it. Also, make sure you have your amp and such properly grounded as well, so you don't have any issues with ground loops and feedback current.
  7. paintandsk8

    paintandsk8 Pushin' my soul through the wire...

    May 12, 2003
    West Lafayette, IN
    In a bass that is well shielded with good materials and good methods bridge grounding is not necessary, passive or active. There are plenty of the threads on this in the Pickups and Electronics forum.

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