Grounding/Shielding with an ungrounded bridge.

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by invertedtremolo, Apr 22, 2008.

  1. invertedtremolo

    invertedtremolo Member

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    Hey there,

    I've got a Schecter C-1 Hellraiser that I'm working on. This guitar usually comes with EMGs, but i've been asked to put duncans in instead. The wiring itself is no big deal, but the problem i'm running into (i think) is that the bridge isn't grounded. The buzz is loud! The string noise doesn't change when i put a hand on the bridge, and it quiets when i put a hand on the pots/switch etc. Now, since they come from the factory with EMGs, I can see why the bridge isn't grounded. My question is: is there a way I can ground the bridge without drilling or anything like that, and will that quiet the noise? I don't have any woodworking skills or whatever, so I'm hoping that adequate shielding of the cavity will do the trick. Am I just hoping in vain?

    Thanks.
     
  2. GuitslingerTim

    GuitslingerTim Member

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    The problem is not the bridge ground (or lack thereof), but a broken ground connection, probably at the input jack.
     
  3. walterw

    walterw Gold Supporting Member

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    actually, this does mean your problem is the bridge ground. you're going to need to pull out one of the bridge stud bushings (the one closest to the knobs) and drill a small tunnel from the side of that hole into the control cavity to run a wire to the back of a pot. the control cavity is already shielded with graphite paint, so that is obviously insufficient.
     
  4. David Collins

    David Collins Member

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    Yup, you'll have to ground the bridge. It's not a big deal, but if you're just not comfortable taking a drill to your guitar it shouldn't be too expensive to have your tech do it.
     
  5. GuitslingerTim

    GuitslingerTim Member

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    I have three guitars that have humbuckers, and no ground connection at the bridge--I get no buzz at all from them.

    If there is a broken ground at the input jack, the symptoms will be a loud buzzing sound that diminishes when the components are touched--how can you tell the difference between an ungrounded bridge and the complete absence of a ground connection, barring an actual inspection of the guitar?
     
  6. David Collins

    David Collins Member

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    To get no buzz with passive pickups and no bridge ground would have to occur under the most ideal circumstances - filtered 110 with perfect neutral ground, and little to no significant electrical noise in the room. Under any normal (less than perfect) circumstances, passive pickups without a grounded bridge will show an increased buzz when you touch the strings. With a grounded bridge, any small buzz from an unbalanced ground in your house will diminish. I'd bet your bridges are grounded whether you know it or not. Touch a meter to the strings and the jack ground, and I'll bet you'll find continuity, which would mean your bridges are grounded. If the ground connection was broken at the jack you would simply get no connection at all.
     
  7. GuitslingerTim

    GuitslingerTim Member

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    The guitars mentioned are all parts guitars I built myself, but with humbuckers, not single coils.
     
  8. Quarter

    Quarter Member

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    You might get lucky and find a pre drilled hole when you pull the bridge stud.
     
  9. Supasso

    Supasso Member

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    If a guitar had a complete absence of a ground connection, there would be no sound coming from the pickups, except the noise, of course.
     
  10. Eagle1

    Eagle1 Member

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    EMGs should not have a bridge ground and I would start looking at component failure as EMG sets require little or no additional screening and are usually dead quiet even at high gain .
     
  11. in a little row

    in a little row Member

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    per the title of the thread...grounding and shielding entail different processes, although when you shield a guitar, you must ground that...

    in regard to shielding, while i dont think this is the solution to the main problem you face, using copper or aluminum shielding tape in the control cavities will help get rid of exterior noise sources...there are several threads on this process...

    if your buzz isnt affected much by touching the bridge but is some by touching the controls, the bridge ground is not your issue

    i shot in the dark on your noise---some kind of a ground loop or contact of uninsulated wires
     
  12. walterw

    walterw Gold Supporting Member

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    actually, it's the exact opposite. the bridge and the strings should be at the same potential as the controls, so touching one should produce the exact same result as touching the other. if not, the bridge is not grounded properly.
     
  13. GtrDr

    GtrDr Member

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