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ALTERNATIVE WIRING FOR PARTIAL COIL CUT. THEORY InPUT APPRECIATED

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  • #16
    OK. While I was waiting a call from the hospital, I've tried to think about something else. So I’ve done a few sims that I share below. Each pic shows ten lines, translating the resonant peak of a humbucker whose coil splitting is progressively altered by a variable resistor (goiing from 500k to 0 Ohm).

    Pic 1 illustrates what happens when a HB in series has the variable resistor between coils, going to ground (as shown by “Fig 1”, in post 1). As I’ve tried (and failed) to make it clear in my post 11, the resistor “mellows” the signal and “flattens” the resonant peak a bit like a tone control would do as long as its resistance is high. It’s only when this resistance is low that one coil starts to “loop” itself to ground, leaving the second coil working alone. That's where the resonant peak becomes higher pitched and the level much lower...


    The second pic shows what happens when a HB wired in parallel has a variable resistor between ONE of its coils and ground (as shown by “Fig 2” in post 1). This time, the control affects essentially the frequency of the resonance, which is logical since it passes the HB from of its series inductance (in parallel) to half of this inductance (when split): it affects frequencies more than output level.

    The third pic shows what happens with a cap in series with the variable resistor, as Gstring has wired it (if I’ve understood correctly what he said)…
    ...And that’s where my previous explanation was not complete at all. :-/
    The 5nF cap has in fact TWO actions in this case:
    -it acts like a tone capacitor to ground for coil 1;
    -it's also a series capacitor between ground and coil 2 and works as a high pass filter for it.
    These two functions contradict each other and create a “dip” in the mids, whose center frequency depends on the capacitance involved.
    The red arrow in the pic shows where is this frequency with a 5nF cap: between 500hz and 1khz.
    In fact, it’s a subtle variation on Gibson’s Fat Tap / tuned coils...

    Don't know if this rambling is clearer than my previous posts. My overloaded mind made my answers wordy and unclear altogether. At least I'll have tried to share something... :-)

    Gstring, you're right anyway: theory is not supremely important compared to practical / musical experience.
    Attached Files
    Last edited by freefrog; 09-26-2020, 08:41 AM.
    Duncan user since the 80's...

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    • #17
      Hey Man

      Seriously appreciate you finding time to respond . Am now a little less confused Thanks

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      • #18
        Gstring,

        I wanted to thank you for posting about this concept of applying a cap & resistor to one of two coils combined in parallel. It is something I am very interested in giving a try. I am currently working up a custom diagram that will allow me to try that as well as try it to those two coils combined in series, so I can A-B compare both at the same time.
        Sanford: "The hardest part about tone chasing is losing the expectations associated with the hardware."

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        • #19
          Originally posted by Gstring View Post
          .
          Have been experimenting for some time with the re wiring one of my favourite 2 vol 2 tone mahogany/maple arch tops. It has 4 CTS push pulls which now give Artie's coil swap , partial coil cut for each pup and a combined Series/OOPs. Have now found a wiring I like but would be interested to learn what is happening theory wise.re the partial coil cut.

          My trial and error experiments have been primarily with the partial coil cuts to get a slightly better (different?)sound than either standard parallel or a straight coil cut. Experiments comparing sounds after adjustments with a single guitar are always a bit hit or miss relying on ear memory but I think I am getting to where I want to be.

          I have found that I prefer the sound of partial coil cuts so that the by bypass filter works only on one coil when the pup is wired in parallel. See extract of my schematic. For simplicity PPs are shown as standard as opposed to convoluted CTS wiring. This wiring I think also gives improved sounds when both the coil swap and partial cut are engaged. Also I think I can hear a slightly sweeter sound iwith a small 0.05 cap added in series to the resistor.

          I am at the moment using 500k pots( cheap imports I had lying around) as resistors to find a value I like . Current favourite values seem to be around 375 ohm for the bridge and 210 for the neck. Single resistors of similar values will eventually be fitted to neaten things up under the hood.

          My electrical theory is very limited and I would be interested to learn from some one more knowledgeable what is the difference in terms of current flow of wiring a partial coil cut as normal (as in fig 1) or of how I have wired it (fig 2) . Also what is it that happens to the “frequency filter” when you wire a small cap in series with a resistor as I have done. I was intrigued out of curiosity to try resistor and cap in parallel as per the de mud mod but never got around to it. If anybody can tell me the likely result in a partial ciol cut situation it would be appreciated.

          Click image for larger version  Name:	Diagramme 24.jpg Views:	120 Size:	45.7 KB ID:	6018677
          Hi GString,

          I've continued to ponder your wiring ideas, and I have a question. When you combine two coils of the same humbucker pup in this way (in parallel but with one coil partially cut), i would suspect that the resultant sound could have some Strat Position 2 type quack present? Of course, the amount of quack would depend on how much the 2nd coil is cut, i.e. the value of the resistor. Would you mind letting me know if my suspicion is correct and what resistor & cap values seemed to produce the highest amount of quack?
          Sanford: "The hardest part about tone chasing is losing the expectations associated with the hardware."

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          • #20
            Originally posted by Jack_TriPpEr View Post

            PM Artie, Freefrog, or GuitarDoc and ask them to take a look at this thread. They might have simply missed it.
            I'm looking at it now. But need a bit more coffee to interpret this one.

            BTW, Jack. I did look at that HCP pot thing, but that's one of those things that I'd have to buy, and hold in my hand, to figure out accurately. Sorry if I didn't respond. Got lot's of "irons-in-the-fire" right now. But I'll look at it, and this thread, again.

            Artie

            Edit: Didn't see freefrog's response when I posted.

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            • #21
              Originally posted by Jack_TriPpEr View Post

              Hi GString,

              I've continued to ponder your wiring ideas, and I have a question. When you combine two coils of the same humbucker pup in this way (in parallel but with one coil partially cut), i would suspect that the resultant sound could have some Strat Position 2 type quack present? Of course, the amount of quack would depend on how much the 2nd coil is cut, i.e. the value of the resistor. Would you mind letting me know if my suspicion is correct and what resistor & cap values seemed to produce the highest amount of quack?
              Member Gstring did reply to my last question above but under a different thread. I am copying that reply here for anyone else that was following this thread.

              Although his response of "cap and resistor in-series *with the pup*" (emphasis added is mine) raises concern that he might not have understood that my question was asking about a cap & resistor in-series *with an individual coil from a humbucker wired in-parallel*, which is the innovative wiring scheme concept he outlayed earlier in this thread.

              Gstring: "As regards getting more 'quack' from a SSS Strat using resistors and caps in series with the pup, this is something I have never experimented with and am not sure if experimenting would produce results of value and there would probably be wiring issues unless it was accepted that the mod was permanently connected. I gather you are experimenting with this so don't let my comments put you off."

              Ref: https://forum.seymourduncan.com/foru...33#post6056533
              Sanford: "The hardest part about tone chasing is losing the expectations associated with the hardware."

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              • #22
                Sorry for not responding, I've been away from the forum for a while. Like Artie, I've got lots of irons in the fire... just moved recently so I've been busy setting up my shop, working on several custom guitars and custom compensated nuts and bridges orders. My paint room isn't quite finished yet so I've been working around that problem as well. But it looks like Artie and Jack have things under control and will give you the best advice that you can get, so I will defer to them.

                Very interesting concept you're working on. IMHO, the subtle change in sound you'll get from all of this complexity won't in reality be noticed by anyone but you. But the learning that you obtain from working through all of this is probably priceless. Good luck.

                Freefrog, sorry to hear about your mom. Mine just passed away two weeks ago (at 99 years old) which in some respects is a bit easier to handle than what you're going through (and will be going through). Best wishes to you and your mom.
                Originally Posted by IanBallard
                Rule of thumb... the more pot you have, the better your tone.

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                • #23
                  Originally posted by GuitarDoc View Post
                  Sorry for not responding, I've been away from the forum for a while. Like Artie, I've got lots of irons in the fire... just moved recently so I've been busy setting up my shop, working on several custom guitars and custom compensated nuts and bridges orders. My paint room isn't quite finished yet so I've been working around that problem as well. But it looks like Artie and Jack have things under control and will give you the best advice that you can get, so I will defer to them.

                  Very interesting concept you're working on. IMHO, the subtle change in sound you'll get from all of this complexity won't in reality be noticed by anyone but you. But the learning that you obtain from working through all of this is probably priceless. Good luck.

                  Freefrog, sorry to hear about your mom. Mine just passed away two weeks ago (at 99 years old) which in some respects is a bit easier to handle than what you're going through (and will be going through). Best wishes to you and your mom.
                  GuitarDoc,

                  Glad to hear from you and that you are well.

                  You're absence has not gone unnoticed here - you have been missed here.

                  Congrats on your recent move and having a new shop to set-up. Sounds exciting.

                  My condolences on the loss of your mom.
                  Sanford: "The hardest part about tone chasing is losing the expectations associated with the hardware."

                  Comment


                  • #24
                    Originally posted by GuitarDoc View Post
                    Freefrog, sorry to hear about your mom. Mine just passed away two weeks ago (at 99 years old) which in some respects is a bit easier to handle than what you're going through (and will be going through). Best wishes to you and your mom.
                    Thx Doc, and all my sincere condolences...
                    Mum is getting better for the moment but the medical context is still there with its weight and exigences. That's life (and it also makes my presence here a bit "erratic").

                    I wish you all the best with your renewed shop and new guitar projects! :-)

                    @ Jack_TriPpEr: my current on / off mode doesn't ease communication but feel free to call me if I can help in any way.


                    Duncan user since the 80's...

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                    • #25
                      Originally posted by freefrog View Post

                      Thx Doc, and all my sincere condolences...
                      Mum is getting better for the moment but the medical context is still there with its weight and exigences. That's life (and it also makes my presence here a bit "erratic").

                      I wish you all the best with your renewed shop and new guitar projects! :-)

                      @ Jack_TriPpEr: my current on / off mode doesn't ease communication but feel free to call me if I can help in any way.

                      Thanks Freefrog,

                      Do you happen to know if Strat Position 2 like "quack" could be a possible sonic result from partially cutting one coil of two coils from the same humbucker that have been wired in parallel? I do understand this would be highly dependent on the degree to how much the 2nd coil is cut/sent to ground.... as well as any cap placed in line and its value.
                      Last edited by Jack_TriPpEr; 02-18-2021, 11:36 AM.
                      Sanford: "The hardest part about tone chasing is losing the expectations associated with the hardware."

                      Comment


                      • #26
                        Originally posted by Jack_TriPpEr View Post

                        Thanks Freefrog,

                        Do you happen to know if Strat Position 2 like "quack" could be a possible sonic result from partially cutting one coil of two coils from the same humbucker that have been wired in parallel? I do understand this would be highly dependent on the degree to how much the 2nd coil is cut/sent to ground.... as well as any cap placed in line and its value.
                        You're welcome. :-)

                        Regarding your question: in my humble experience and opinion, the result obtained by tuning such circuits really depends on the pickup(s) used with their distinctive inductance and Q factor.
                        Now, what you want should be reasonably approximated by a "fat tap" wiring involving a low value cap (4,7nF / 3.9nF / 3.3nF / 2.7nF / 2.2nF... adjust to taste in order to obtain a dip @ +/- 2khz).
                        It might be interesting to try with a Custom hybrid - and with the SH1 coil filtered out while the stronger Custom coil would remain enabled...
                        Duncan user since the 80's...

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