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Thread: Does this look sensible?

  1. #1
    Member G-Axe's Avatar
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    Does this look sensible?

    Hey guys,

    I've built a bunch of guitars and a bunch of pedals but I've never actually plotted out my own circuit. Here's what I'm trying to accomplish with an MN taper dual gang pot and a humbucker:

    Dial Position
    - Centre detent - full humbucker (ie both coils wired in series, polarity reversed on one side)
    - Full right - right coil only
    - Full left - left coil only

    And here's what I've got for the wiring:

    Click image for larger version. 

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    (as per Seymour Duncan colour codes)
    GREEN = start of adjustable/south coil
    RED = finish of adjustable/south coil
    BLACK = start of stud/north coil
    WHITE = finish of stud/north coil

    So my thinking is that Green will always go to ground, and on the top pot the wiper blends between ground and the hot output of the south coil (red), then feeds that on to the north coil (white). On the bottom pot, I have the hot output (yellow) from the wiper panning between the output of the north coil and the output of the south coil. It seems okay to me, but I'm wondering if there's an issue in wiring the south coil output to both pots. I can live with a bit of weirdness in the blend between the black and red on the bottom pot, as long as it behaves properly at both extents of the taper.

    Any help from someone more experienced with this sort of thing would be much appreciated!
    Last edited by G-Axe; 01-03-2019 at 08:25 AM.

  2. #2
    Mentor fender3x's Avatar
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    Hi G-Axe,

    I have never tried to do this, and would be curious if anyone else has. It would be nice to cheat and look at someone else's wiring scheme.

    The problem that I keep running into as I run it through my head is that the signal path in series humbucker goes through both coils. Hot is the black wire and ground is green, but the red and white have to connect to complete the circuit. Otherwise neither coil is going to make any noise. Turning down one coil diminishes signal moving through the circuit even if the other coil is at 100%. There may be a way to do it, but it's not obvious to my uneducated brain.

    I also wonder how worth doing this is. My experience is mostly with basses, so YMMV. I have a bass where I can turn put each pickup in Single-coil-bridge, series, parallel, and Single-coil-neck. There is a marked difference between series, parallel and single coil. But blindfolded I am not sure I could tell the difference between SC-neck and SC-bridge.

    Please be aware that I have no EE training whatsoever!

  3. #3
    Member G-Axe's Avatar
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    Quote Originally Posted by fender3x View Post
    I also wonder how worth doing this is.
    Oh, it's absolutely not, but I'm doing a $0 build and this is what I've got lying around - so I want to get creative.

    The problem that I keep running into as I run it through my head is that the signal path in series humbucker goes through both coils. Hot is the black wire and ground is green, but the red and white have to connect to complete the circuit. Otherwise neither coil is going to make any noise. Turning down one coil diminishes signal moving through the circuit even if the other coil is at 100%. There may be a way to do it, but it's not obvious to my uneducated brain.
    I might just have to wire it up and see how it goes. By my logic it should work at the extents:

    - At full right, the white is grounded, and the black goes to output. Green is also grounded, red goes nowhere.
    - At full left, green is grounded and red goes to output. Red also goes to white, but black goes nowhere.
    - At centre, green is grounded, red goes to white, black goes to output. Red also has a jumper going nowhere.

    And I guess it's there "nowheres" that I'm unsure about in EE terms. My assumption is that if the current has nowhere to flow, that branch is null and void. Does that sound right?

    There's obviously going to be all sorts of weirdness when the red is blended between white and output, but I can live with that.



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  4. #4
    Overlord of Music WeirdBits's Avatar
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    You can simplify it a bit, same colours as your diagram:
    Click image for larger version. 

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    Larger value pots have less effect on the sound at the centre detent, but can be more 'switchy' when turned (small change then coil off). Smaller value pots have a more gradual change but are potentially more noticeable at the centre (greater percentage going through the resistance of the pot).
    Scott.

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