4-wire pickup issue with splitting the coils

Discussion in 'The Tone Zone' started by Macro, Mar 24, 2012.

  1. Macro

    Macro Well-Known Member

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    Talking about Seymour Duncan pickups specifically...

    On the duncan 4-wire humbuckers, the color codes are as follows...

    [​IMG]

    I want to set up a switch to select either side, or both in series.

    Im starting out with just a simple practice amp and a patch cable. (wanted to check my wiring before hooking anything up)

    When I connect the green lead to the common wire of the cable, and the red wire to the tip, I still get sound out of both sides of the humbucker. In this case, the south side is louder and more prominent than the north, but the north is still making noise (even though the white and black wires are unconnected to anything)

    The opposite happens if I connect the black and white leads to the patch cable....the north is louder but the south still 'picks up' noise.

    At first I thought something was wrong with the pickup, so I tried another one I had....same issue. (and these are both brand new pickups)

    What is going on?

    I really want to be able to get three options out of the humbucker....the north, the south, or everything in series for full humbucker sound.

    What am I missing?
     
  2. LuredMaul

    LuredMaul Active Member

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    what pickup?
     
  3. LuredMaul

    LuredMaul Active Member

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  4. Macro

    Macro Well-Known Member

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    That is a pretty awesome site....thanks for sharing the link.

    Unfortunately, I cant get the issue to work with just the pickup and a cable...getting into the switching configuration is a next step...but I need to figure out the first step first.

    I cant isolate the north and south coils...im wondering if one is inducing the other....if the wiring diagram is accurate, when I hook up one coil, the other is completely unwired to anything. I dont understand how it is picking up anything...the only possible connection would be magnetic field....there is no physical connection between conductors (that I know of)
     
  5. brp

    brp Well-Known Member

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    How are you sure that it is? Not by tapping the poles on the coil you expect to be not functioning I hope.

    I couldn't find the S Duncan diagram for what you are doing but here's the diagram for Dimarzio for what you want to do

    http://www.dimarzio.com/sites/default/files/diagrams/1humdpdt_lcoilseriesrcoil.pdf

    You can use this diagram but just change the wire color to the appropriate ones for SD 4 wire pickups using this key:

    Dimarzio red = SD BLACK
    " " black = SD WHITE
    " " white = SD RED
    " " green = SD GREEN

    Double check this code key for yourself here:
    Guitar & Bass 4-Wire Humbucker Color Code Diagrams

    Or just use this one
    http://www.guitarelectronics.com/pr...bucker1-VolumePull-for-South-Single-Coil.html
    if you know what the wires for each coil are for SD 4 wire pups.


    Hope this helps.
     
  6. Macro

    Macro Well-Known Member

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    The method I have always used is to hook the pickup wires to a guitar cable, plug into an amp on clean channel on low volume, then touch a paper clip to a pole in the coil I am testing and gently slide it around on the surface. If the coil is hot you hear a scraping noise through the speaker...if the coil is dead, you might get a very faint noise picked by another active coil, but it's clearly not 'picking up'

    With the pickups in question, the 'dead' coil is absolutely picking up...it is microphonic without question....I've triple checked the schematics for the pickups....it's standard 4 wire (and I know the start and finish for each coil). At this point I m wondering if I could have two pickups that simply have a short among the windings somewhere within the bobbin. I can't rationalize any other way this is happening.

    I even tried to ground both ends of the coil for the side I don't want picking up....and it still picks up noise.

    I think I need to pull a pickup from a guitar th works correctly....if I get a chance I'll do this later today.
     
  7. Micky

    Micky Well-Known Member VIP Member

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    Have you put a meter on the coils yet?
    Any chance you have the wire color code different?
     
  8. Macro

    Macro Well-Known Member

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    I am getting about 8.1k ohms across each coil...the color coding I am working from appears to be correct. I am seeing around 2-3M ohms of resistance in the isolation between the two windings.*

    When I individually connect the coils to an amp, you can hear a clear difference between the active circuit and the coil that isn't physically connected...still, the induced coil is picking up noise...not much, but it's there.

    This is the first time I really picked apart a 4 wire humbucker on the test bench....guess I was expecting absolutely isolated coils. In my perfect world, until I physically connected the end of one coil to the start of another, the two would have no electrical relationship. In my case, it appears that the isolation isn't 100%. A few mega Ohms is pretty decent isolation, guess I just expected it to be infinity :)

    I'll wire this thing up with my DPDT switch when I get a chance. Hoping that once everything is soldered up properly (and all the associated grounds are established) that the isolation will be more apparent.
     
  9. JohnH

    JohnH Well-Known Member

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    Definately measure with a multimeter to make sure you are getting about half the resistance in the split modes.

    But you will get magnetic coupling. If you connect to one coil only, and tap the other one, you will get a sound because they are all within the same magnetic field. Its normal, but the connected coil will be stronger and you will still get a more single coil sound.
     
  10. Micky

    Micky Well-Known Member VIP Member

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    I think you are experiencing the 'humbucking' effect, where the other wind is actually being induced as you have observed. Hopefully Rayne will chime in here and pick this subject apart for us.
     
  11. MajorNut1967

    MajorNut1967 New Member

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  12. MajorNut1967

    MajorNut1967 New Member

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    Use a SPDT 3 position on/off/on
     
  13. Macro

    Macro Well-Known Member

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    The resistance is pretty much spot on....16.2k across both coils in series...8.1k individually. And I think you are right....it appears that the unconnected coil is simply within the active field. Probably a function of the pickup itself...the Seymour Duncan hotrails is a small package with a lot of wire...lot of field across two rails that site about a centimeter apart.

    I think all is cool...just need to wire it up and see what it sounds like in the guitar, and not worry about meter readings on my bench :)
     
  14. Macro

    Macro Well-Known Member

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    The resistance is pretty much spot on....16.2k across both coils in series...8.1k individually. And I think you are right....it appears that the unconnected coil is simply within the active field. Probably a function of the pickup itself...the Seymour Duncan hotrails is a small package with a lot of wire...lot of field across two rails that site about a centimeter apart.

    I think all is cool...just need to wire it up and see what it sounds like in the guitar, and not worry about meter readings on my bench :)
     
  15. Macro

    Macro Well-Known Member

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    Actually using a DPDT on on on

    Easier for the specific application I have in mind.

    The circuit design was the easy part...my issue was more a matter of the pickup construction.
     
  16. MajorNut1967

    MajorNut1967 New Member

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    No on/off/on
     
  17. Macro

    Macro Well-Known Member

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    The circuit I designed uses an on-on-on switch.

    How would you use a 3-way on-off-on to accomplish the following...

    Position 1 - one half of the humbucker active
    Middle position - full series humbucking
    Position 3 - the other half of the humbucker active.

    In the middle position I want series wiring, not parallel.

    Seems easier to do this with an on-on-on
     
  18. JohnH

    JohnH Well-Known Member

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    You can use on-on-on, or on-off-on, with the wiring to suit. Acyually, the on-off-on one is simpler, since you only need half of a dpdt switch, but either can work fine.
     

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