Partial Coil Split with TrimPot question please

[powerex21]

Hi All, have a wiring query and hope someone would be able to chime in.

My current guitar has HH Thornbuckers installed and I am looking to have a single coil split (screw side, coil that is nearer the neck) from the neck humbucker in position 4 using a trimpot so that I can decide what resistance level would be the sweet spot (volume loss vs single coil tone).

I brought my guitar to the guitar mechanic and the feedback that I got is that the slug/north side is the coil that is 'always on' with the screw side that gets added into the mix (with the trimpot modification) and having the screw side as the coil that is 'always on' is not possible.

Does anyone have any ideas if it would be possible to have the screw side (that is nearer the neck) always on and have the slug side added into the mix instead, without having to use a push-pull pot or going out-of-phase?

Thanks.

 

[Peegoo]

You need a "four-wire" humbucker. Here's what you want:

 

[powerex21]

Thanks, the current humbuckers are already on a "four-wire" configuration.

The confusion is whether if the wiring can be configured so that the screw side coil nearer the neck (instead of the other coil) is fully turned on when the pot is at the zero position, because the shop is saying that it cannot be done?

Which I guess prompts the question, if the wiring can be 'configured' so that it selects either coil as the main 'full-on' coil when the trimpot is set at zero.

 

[Deaf Eddie]

With a traditional coil-shunt, you rout the series pair (here, the red and white leads) to ground, and you get the slug coil playing with the screw coil shunted. BUT, if you rout the series pair to the pickup's HOT, you will shunt the slug coil and play the screw coil - which is what you asked for.

I do this quite often (shunt the slug coil to play the screw coil). When you are in coil-shunt, IF you shunt the slug of one pickup and the screw coil of the other, you keep a "noise cancelling" pair of coils when playing both pickups together.

Back to your spin-a-split question, I haven't tried a spin-a-split myself, but it SEEMS to me that if you rout the lead from the right-hand lug of the split pot (in the above drawing) going to the pickup's hot, instead of ground, you will get what you asked for. It would look like this edit of the above drawing:

IF you try this, please post the results!

Perhaps someone will chime in with an opinion...

 

[Peegoo]

Thanks, the current humbuckers are already on a "four-wire" configuration.

The confusion is whether if the wiring can be configured so that the screw side coil nearer the neck (instead of the other coil) is fully turned on when the pot is at the zero position, because the shop is saying that it cannot be done?

Which I guess prompts the question, if the wiring can be 'configured' so that it selects either coil as the main 'full-on' coil when the trimpot is set at zero.

Yes, it can be done; you can have the screw side of the coil on and the slug side go dark with the split pot.

You can simplify the concept if you think of a humbucker as two single-coil pickups.

In my diagram above, the slug coils' leads are black and white, and the screw coil's leads are red and green. You join the white and red to place the coils in series. You can choose which coil remains active when the split pot is rolled all the way off by how you connect the four wires.

Another way to do it would be to use a blend pot (the type with center detent) and treat each coil of the humbucker as two separate pickups.