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Post by isher on Jul 14, 2013 17:32:51 GMT -5
New to the thread, but this is something I've been asking other places and can't find an answer to. I have an Ibanez ATK that I'm changing the preamp to passive, and the Ibanez "Triple coil" is really a humbucker with a dummy coil, and the factory switch is designed to act like a parallel humbucker, and then in two other positions, as a single coil with a dummy coil for noise cancellation. I want to change this to have a volume knob across each of the two coils (Standard 4-conductor wiring with a shield) and then have both coil volumes feed into a master series-parallel switch, then go to a tone knob with a "Varitone" style circuit. Here's a diagram of how I THINK it should be done, but I'm not entirely sure and any feedback is appreciated. I wire each coil like a single coil pickup to the volume pot, then use a wire from lug one of each pot as the positive and the ground as the negative to the switch, right?
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Post by newey on Jul 14, 2013 22:29:55 GMT -5
Isher-
Hello and Welcome to G-Nutz2!
I see a couple of issues. First, I'm not sure than you can wire the volume pots that way for the series position, as turning either one down will cut all the output when in series. I'll let others weigh in on that aspect.
I don't know that I've seen a Varitone circuit with a separate switch for the inductor, either. No reason I can think of that it wouldn't work, though.
However, you have a more basic problem with your series/parallel switch wiring. In order to have the two coils in series, one of the grounds has to be, as they say, "lifted". To make the series chain, the "-" of one coil has to be wired to the "+" of the other, and it can't also be grounded at the same time, or one of the coils will be shorted out. You show the "N" coil negative as the one which should be lifted, but you haven't in fact lifted it.
You have both coils "-" wires going to the pot, then being grounded to the back of the pot. The pot grounds are then noted to be tied together. So, both coils "negative" wires will always be permanently grounded- not what you want. You have to "lift" the ground of the one coil which attached to the "+" of the other when in series.
I wouldn't wire either one of the "-" wires to the pots anyway, but the "N" coil negative has to be lifted. So, disconnect N- from the pot and wire it directly to the middle lug, left side, of the DPDT switch. Then just ground the third lug of the pot (as it is now shown on the diagram.)
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Post by JohnH on Jul 15, 2013 4:29:32 GMT -5
Controlling relative volumes of two coils, or two pickups, in series and in parallel is trickier than you might think it should be. Getting an arrangement where you can set in-between blends in both states over a reasonable turn of pot, without creating a bunch of duff sounds in various settings often turns out to be impractical or impossible. As you have it, there are nice high impedance pots to avoid loading the coils, but in parallel mode, as soon as you turn one down it will almost dissappear from the mix, and in series mode, both will be mud! Ive tried a few ways with guitar, and I see yours is a bass which might affect values. My LP works quite well, with each pickup having forwards wired volume pot, ie, coils go to the volume pot outer lugs, and the centre lug goes to output. Essential to this arrangement is a treble bleed circuit, a cap and resistor in parallel from inner to hot outer lugs. The output of the pickup and pot is then a unit with two wires, put into series or parallel with the other pickup. But in parallel, turning one off turns everything off when both are selected. guitarnuts2.proboards.com/thread/4571/humbuckers-lp-modular-wiring-designAnother version might be to say that in parallel mode, theres no blending, and in series mode, you can fade out one coil to make single mode. Blending in series always seems to sound more interesting to me. So you could have a series blender/mixer and a master volume.
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