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Epiphone EB-3 bridge pickup/ Gibson varitone choke circuit.

Discussion in 'Pickups & Electronics [BG]' started by RobbieNuke, Jan 2, 2012.


  1. RobbieNuke

    RobbieNuke

    Jan 22, 2008
    Baltimore
    I am retrofitting an original Gibson EB-3 choke circuit in my Epiphone EB-3. Read somewhere that the bridge pickup need to be reversed phased if doing this. Anyone experienced with this?

    While removing the original wiring harness from my Epiphone EB-3, I noticed the bridge pickup has a 4-wire (red/white/green/black) + shield cable. The green/white wires are taped together. I guess I could do a phase inversion or series/parallel by adding a mini-toggle switch.
     
  2. SGD Lutherie

    SGD Lutherie Banned Commercial User

    Aug 21, 2008
    Bloomfield, NJ
    Owner, SGD Music Products
    There's no reason to do that. That would give you a thin tone.

    Here's the real circuit:

    http://www.gibson.com/Files/schematics/EB3series2.PDF
     
  3. jumbodbassman

    jumbodbassman Supporting Member

    Dec 28, 2009
    Stuck in traffic -NY & CT
    Born Again Tubey
    how does one read that???
     
  4. RobbieNuke

    RobbieNuke

    Jan 22, 2008
    Baltimore
    Read somewhere that Gibson reverse wound the bridge PU because the choke circuit would throw the signal out of phase with the neck PU when both are actuated, giving it the thin sound you describe. Your series 2 schematic is different from the series 1 schematic where the choke circuit is only introduced in 1 position with the neck PU only (the Series 1 circuit is the one I'm emulating in that the coil is always tied-in to the circuit of the neck PU). I've listened to samples of both circuits and the series 1 has a much wider variety of timbres therefore the one I'm copying.
     
  5. SGD Lutherie

    SGD Lutherie Banned Commercial User

    Aug 21, 2008
    Bloomfield, NJ
    Owner, SGD Music Products
    You can't reverse wind a humbucker. It has two coils, which are opposite polarity from each other, so the output is a composite of the two.

    The choke does not change the phase of the signal. When used in this manner, it's in parallel to the pickup, and is shunting the midrange along with the cap.

    In fact, the Gibson choke is a humbucker, and has two of its own coils to prevent the inductor from picking up noise.
     
  6. It's pretty much standard VVTT wiring with a pickup selector, plus a capacitor in series with a choke, which is switched into the circuit for one of the pickup selector's positions only.
     
  7. top028

    top028

    Dec 14, 1999
    Lancaster, PA
    Any of you guys still around? I know I read about phase of the bridge pickup too. I am thinking about doing this. Anyone know if I have to put another 3 conductor wire on the pickup? IS it worth it, thats the real question.
     

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