single-coil / humbucker hybrid wiring

I was reading about a PMT (brand) HPC (Humbucker Contol Pot) and it gave me some ideas.

In one mode, it wires a humbucker so that both coils work for bass and cancel the prominent 50 or 60 cycle hum, but only one coil works for mids and treble.

This is, IMHO, a fabulous idea with implications and possibliities. Just cut the treble from just ONE coil.

When the two coils are in series: You can just switch a cap in parallel with one coil for a first-order filter that turns off the treble on one coil.
The bass would be louder than a normal singel-coil, but that too could be interesting to have full bass like a hukmbucker yet clear balanced treble like a single-coil. For a second-order filter, you'd need an inductor in series with the coil, then a cap across both the pickup and inductor. If you did it backwards the inductor would cut treble for both pickups, but done correctly the same cap that cuts the treble from one also give the treble from the other a path around the inductor.

When the two coils are in parallel: everything is reversed of course. An inductor in series with one coil would make a first-order filter to cut the treble in that one pickup. Just a cap across one would affect both coils. But a cap across one, then an inductor in series with that pickup and cap, all that in parallel with the other coil...the cap and inductor in series would make a load somewhat frequency-consistent so a not to affect the other pickup too much I hope.

Of course, working in the real world we have to consider using zobels or considering the existing inductance of the coils, and maybe resistors to control filter slope etc. etc.

Now consider a classic problem. A guy has an old SG with P90 soapbars and loves the sound. But when he works bars with light dimmers and neon signs, with a high-gain amp they hum a lot. So I gave him a phase switch on a push/pull knob and the hum is gone, and pinch harmonics pop out like magic. sounds out of phase. SO...I could wire it up with the treble & mids in-phase but the bass out of phase. That's not going to give full bass either, but the mids and treble may sound more like a single-coil.

This calls for some experimentation.
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