G&L tone circuit question

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by sixty-four, Jun 27, 2008.

  1. sixty-four

    sixty-four Member

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    Hey all,

    I installed a JB in the bridge of my G&L Comanche that is wired exactly like the S-500. I noticed that the JB sounds extremely dark and muddy. How's that for unexpected?

    I was wondering if some of the kind folks here could take a look at the PDF schematic and see if anything might be suspect. I'm wondering myself about what the C3 cap does.

    Here's the schematic:

    http://www.glguitars.com/schematics/S-500_schematic_blockdiagram.pdf

    Thanks!
     
  2. frankencat

    frankencat Guitarded Gold Supporting Member

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    That's the classic G&L bass/treble circuit. Dark and muddy huh? Maybe swap out the volume pot for a 500k. If that doesn't do it then something is either not wired correctly or there is something wrong with the pickup. Personally I like JB's with 250k pots and they are definitely not dark or muddy fwiw.
     
  3. Boris Bubbanov

    Boris Bubbanov Member

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    Reinstall the stock Z-coil and crank it up and see if you have hurt something thar under the hood.

    Test the SD on another guitar for basic function.

    I would expect the JB to work way better on a Legacy; I never considered trying one on one of my Comanches. Did you do a second pickguard, I hope?


    Bubban0v
     
  4. sixty-four

    sixty-four Member

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    Yeah dark and muddy was definitely unexpected.

    I do have the original pickguard so reversing this would be pretty simple...assuming I didn't screw anything else up in the process

    I don't think it's the pickup. I haven't tried this JB in another guitar but I have tried 2 other pickups in my Comanche with the same basic results.
     
  5. tubeboy76

    tubeboy76 Member

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    Try pulling C2 out of that circuit. It looks like a treble bleed but it could darken up your buckers. Also, meter out that JB. It should read 16.4Kohms (give or take). If it reads higher than about 17K I would replace it. Also, I assume you have checked the pu height and don't have it wired with one of the phase wires instead of the hot?
     
  6. sixty-four

    sixty-four Member

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    Just a quick follow-up.

    I checked the resistance on 2 JB's - one from my Comanche the other the stock TB-4 on my Legacy HB. Both read hot - near 18K. However, the JB in the Legacy HB didn't sound dull and lifeless. It was bright and defined.

    I did yank the .001uF cap (C3 in the schematic) and that brightened up my guitar. I think that was the culprit as my Legacy HB does not have that cap in it's otherwise identical schematic.
     

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