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Dummy coil push pull wiring help

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  • Dummy coil push pull wiring help

    A friend on a social media website asked me how to wire up a dummy coil and I couldn't find much help on google as I've always been a 4 wire humbucker guy myself. I did however find some really sloppy diagrams that didn't help. Anyways after 20 minutes of googling I drew this out and really I'm after a second opinion as I don't have a strat to mess around with and do this on.

    Any other insight about them such as if there is a correlation between DC resistance helping to cancel the hum or anything people may not know about this I'd love to know.

    the wiring is a basic fender strat style so really we're just adding the dummy coil to the push pull. This is a quick drawing I did in photoshop.


  • #2
    Re: Dummy coil push pull wiring help

    Originally posted by shadowfire90 View Post
    A friend on a social media website asked me how to wire up a dummy coil and I couldn't find much help on google as I've always been a 4 wire humbucker guy myself. I did however find some really sloppy diagrams that didn't help. Anyways after 20 minutes of googling I drew this out and really I'm after a second opinion as I don't have a strat to mess around with and do this on.

    Any other insight about them such as if there is a correlation between DC resistance helping to cancel the hum or anything people may not know about this I'd love to know.

    the wiring is a basic fender strat style so really we're just adding the dummy coil to the push pull. This is a quick drawing I did in photoshop.

    [ATTACH=CONFIG]102857[/ATTACH]
    Quick answer 'cause I'm busy.

    1)No, there's no correlation between DCR and noise cancellation. An Ilitch air coil measures something like 180 Ohm (0.18k) and cancels the noise of a 6k single coil... Reason: the ability of a coil to produce noise (and therefore to cancel it once the phase reversed) is defined by the ratio between number of turns and perimeter. With a same perimeter, the number of turns matters, not the DCR. That's the principle behind DiMarzio "Dual Resonance" : two coils have different DCR values since they've been wound with different wire gauges BUT they are cancelling the noise because they feature the same number of turns around the same kind of bobbin (with a bobbin made of steel, things would differ but that's not my point here).

    2)Personally, I like to wire the dummy coil to the bridge and neck SC's only: their grounds go together to the center lug (or better: to the center lugS) of a DPDT. One position connects these ground wires to... ground. The other position makes the ground wire signal going through the dummy coil, itself permanently connected to ground.
    It allows to keep a totally normal wiring for the 5 positions switch.

    YMMV.

    I hope my post to be clear although it has been wrote hastily . Feel free to ask me what I mean... or to correct any bad wording. :-)

    Good luck in your wiring!
    Last edited by freefrog; 01-18-2020, 03:03 PM.
    Duncan user since the 80's...

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    • #3
      Dummy coil push pull wiring help

      I recall reading a post on here that wiring in parallel or series altered the treble rolloff vs noise cancellation. I think the member was either uOpt or ItsaBass? Someone was commenting on another dummy coil thread. Worth a search.

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      • #4
        Re: Dummy coil push pull wiring help

        The EQ differences make sense absolutely. After drawing this idea out I had an idea with a super 5 way switch I saw a youtube video the guy ended up using to make positions 1/3/5 possible on a super 5 way switch only with three standard single coils. I understood it enough to modify it. Once I have assurance on that diagram I'll be sure to post the more ambitious one in this thread.

        On this particular diagram I'm 90% sure it'll work so I figured I'd bounce some ideas off of you guys just to see if it doesn't as I don't have any squiers or anything kicking around like I usually do to try these mods out. As it's just theory at this point. It's safe to say but I could go series or parallel for my dummy coils and still get hum cancellation yet of course series would be the louder of the 2 as we're increasing the Inductance and DC resistance.

        and you're insightful as always freefrog as I remember when I posted the Torres mids boost and scoop mod a while ago you were the most helpful. thanks for the tips so far guys.

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        • #5
          Re: Dummy coil push pull wiring help

          thanks for the tips so far guys.
          you're welcome.

          On parallel vs series: a dummy coil in series increases the inductance and DCR. In parallel, it divides these values, making the signal higher pitched and quieter.

          So, in a Strat (with normal PU's), a parallel dummy coil would make the pickups way too weak sounding. Even in series, it diminishes the ouput level... but at least the increased inductance minimizes the loss.

          More later if time permits. :-)
          Last edited by freefrog; 01-19-2020, 05:17 AM. Reason: Syntax...
          Duncan user since the 80's...

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          • #6
            Re: Dummy coil push pull wiring help

            I always liked Music Man's Silent Circuit, which used an active dummy coil.
            Administrator of the SDUGF

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            • #7
              Re: Dummy coil push pull wiring help

              Shouldn't the dummy coil be tuned for the specific application? I tried once and it sucked. Noise reduction was minimal and the placement of the extra coil (ehhm pup) was .... not so pretty.

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              • #8
                Re: Dummy coil push pull wiring help

                Originally posted by greekdude View Post
                Shouldn't the dummy coil be tuned for the specific application? I tried once and it sucked. Noise reduction was minimal and the placement of the extra coil (ehhm pup) was .... not so pretty.
                Some "fine tuning" might be required if the noise cancelling coil alone has not the same sensitivity to noise than the pickup(s). but it's not absolutely necessary IMHO/IME. The addition of "tuning" trim pots to Ilitch systems is due to the fact that a same generic noise cancelling air coil is supposed to be used with various brands of single coils, exhibiting different numbers of turns / tendencies to hum.
                Last edited by freefrog; 01-20-2020, 03:09 PM.
                Duncan user since the 80's...

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                • #9
                  Re: Dummy coil push pull wiring help

                  I agree I'm not big on the idea of dummy coils as a pretty much universal 2nd / 4th position isn't too desirable as the sparkle and uniqueness goes in a pickup but the friend is stubborn to keep his precious single coils and not change anything else.

                  This was something I came up with inspired by a youtuber. Haven't tried it yet but under the hood it'll look ugly but theoretically this should buck all the hum in positions 1/3/5, will it sound good? Probably not but I was bored and this was unique. Haven't tested this yet. As like before I don't have a strat but have wired up my share of guitars so this is based on theory. I kind of wanted to make when the dummy coil was engaged it would be on fully (opposite to the tone) but this seemed the most useful.

                  what I added onto this was an ability for the 3rd position to change polarity to cancel the hum in position 3 only and a push pull for a secondary tone. The dummy coil blends in too so you can still get that strat sparkle when needed.

                  if either diagram has any mistakes let me know

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