Noise reduction/shielding with P90's

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by Zexcoil, Sep 27, 2005.

  1. Zexcoil

    Zexcoil Vendor

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    I've got an old SG Special with original P90's

    They sound great but they buzz like crazy!

    This is a '67 with the pick guard mounted dog ears (adjustable height).

    Is shielding the back of the pickguard and the body cavity going to help control the buzz? I would think it would.

    Problem is, if it is only a marginal improvement, I don't want to screw up a nice vintage instrument.

    On the other hand if it will help tame the buzz, I'd love to make this axe more playable.

    I'm thinking conductive paint in the cavity, and foil on the back of the pickguard.

    The control cavity seems to be pretty well shielded already. Could probably use foil on the back of the cover (may be there already, I can't remember).

    Anyone with experience on this?

    Scott
     
  2. AaeCee

    AaeCee Member

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    I would think very hard before making ANY changes to a vintage instrument, especially permanent changes. HOWEVER, I've always been told (by informed sources) that most shielding issues, or lack thereof, result from insufficient insulation (shielding) on the internal wiring. Lining the inner guard may help a little, but to fully rectify the issue, deeper changes are probably required. Of course, P-90s will always generate more noise than a 'bucker, but a modern P-90 equipped LP I own is quite well behaved, probably due to updated wiring. AC
     
  3. Zexcoil

    Zexcoil Vendor

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    Good advice.

    I'm rethinking the conductive paint idea.

    I used copper mesh to shield a Strat a few years back. I've just got it tacked down. It looks like crap, but it works, and if I took it out you would never know it was there.

    I'm not that worried about a little foil on the back of the guard, but I could see someone getting upset about not being able to see the finish in the pickup cavity.
     
  4. AaeCee

    AaeCee Member

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    Or the fact that you replaced most of the wiring. It's not the cavities so much as the actual type of insulation used on the wiring. So if it sounds good as is, embrace the hum! AC
     
  5. Chiba

    Chiba Gold Supporting Member

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    Another thing you could do - and I know this is gonna sound weird - is shield the inside of the pickup covers.

    Get some replacement covers, coat the inside with copper tape, and see if that helps.

    I wouldn't even suggest it, except I saw it done once (even helped do it myself on a subsequent instrument) and it really worked.

    --chiba
     
  6. Zexcoil

    Zexcoil Vendor

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    Chiba,

    I was thinking about that. I wonder how much it would effect the tone?

    Replacement covers are a good idea, then I can always go back. I think I'll do that first and see how it works.
     
  7. Zexcoil

    Zexcoil Vendor

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    So....

    I tried the new cover with copper foil idea, and.....

    I think it works! I played a house party last night and used the SG quite a bit. It was much more quiet than the last gig. I'm sure the power was probably cleaner in the house. The true test will be Nov 5 when we play the same club again.

    I'll update then, but I'm encouraged!

    Anyone else thinking of making this mod, it was pretty straightforward, and I it can be reversed easily. Basically all I did was line the inside of the cover with adhesive-backed copper foil (foil and covers from WD music). I overlapped a little over one side, tacked a wire to it and grounded the shield. I had to modify the depth of the covers with a dremel as they were too deep, but otherwise it was pretty easy.
     
  8. Chiba

    Chiba Gold Supporting Member

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    Unfortunately I can't speak to any tone difference - I didn't get to hear the guitars before they were shielded (new guitars, fresh installs, and then they went to Japan - but man they sounded good!!).

    Glad to hear the prelim report is good - it's always cool when something like that works out :)

    --chiba
     
  9. Zexcoil

    Zexcoil Vendor

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    Thought I'd close this one out...

    I played the SG Special quite a bit in a club on Wednesday night. Actually I ended up playing it a lot more than I originally intended to, since my JV Strat wasn't feeling right on some stuff, and it just sounded SO GOOD!

    A few disconnects; this was the first time that we played a new club and it's a lot newer contstruction than the place where I had the serious noise issues so I assume the power is cleaner, also no flourescent lights real close, but it was pretty quiet. Certainly not noiseless, but very manageable. Nice and thick, my drummer loved it!

    I would recommend this fix.
     

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