Adding a resistor to a pickups hot lead?

[Tony Lewis Skypilot Guitar Repair]

Two options? 1) Put 250k resistors on hot leads from neck and bridge pick ups and leave middle pick up alone. 2). Add 250k volume pot for neck and bridge pick ups and use existing 500k volume pot for middle pick up. I don’t think you want to mess with middle pick up as customer likes the sound. You can mess with the others because those sounds are have yet to be determined and will be new to customer.

[David Ross David Ross Musical Instruments]

Thanks Tony, I’m leaning towards trying the 250k resistors on the leads of the bridge and neck humbuckers. I may even play around with this on one of my own guitars and see what the effects are.

[Tony Lewis Skypilot Guitar Repair]

Ya cool. That should work. Great to be able to experiment!

[Gerry Hayes Haze Guitars]

Hey Tony

Just want to add a bit of nuance here. Generally, to do this job we’d be adding a resistor between the chosen pickups hot connection and a ground point. The idea is to add another 500K resistor in parallel across the existing 500K pot so that the overall resistance is halved and becomes, effectively, 250K.

This can be done at the volume pot (from the input lug to ground) but that would make it apply to all pickups so it’s usually a better idea to take resistor from the each chosen pickup’s hot switch lug and connect the other end to ground. That means, you’d have two separate resistors, one for each pickup you’re affecting.

There isn’t an easily sourced 500K resistor so you’ll want to use two 470K resistors for the job.

I don’t know the Semi-Hollow circuit so I can’t tell you for sure where to go. If you trace the bridge and neck hot wires to the 5-way pickup selector switch, you can use these to connect one leg of each resistor. Connect the other to ground (insulate the legs if they are at risk of shorting).

For mix positions, you’ll have the middle pickup seeing the 250K volume pot but, when isolated, the middle pickup will still see the 500K pot. If you want this to be different, you’ll need to look at SuperSwitches and things get a little more complicated.

[David Ross David Ross Musical Instruments]

Hey Gerry, thanks for the info. I actually posted about this guitar last November and still have the wiring diagrams that I used. The first picture is the original wiring diagram, the second picture is push/pull switching setup, and the third picture is the wiring that my customer’s guitar currently has.

I posted a thread about it too which should make things clearer:
https://dev.loothgroup.com/all-forums-all-topics/topic/prs-special-22-sh-wiring-help/

dev.loothgroup.com

PRS Special 22 SH Wiring Help??? - Quick Questions - The Looth Group

PRS Special 22 SH Wiring Help??? - Quick Questions - The Looth Group

[Gerry Hayes Haze Guitars]

Hey David

Thanks for that. If I’m understanding everything, using your push-pull you have a way to isolate just the middle pickup alone.

That gives us an option… We can add a resistor between the switch hot output (the yellow circle at the switch in your drawing) and a ground point. That will make all pickup selections on the 5-way switch see a 250K(ish) pot.

When you pull your push-pull, that will take the 5-way switch out of the circuit and send only the middle pickup to the volume pot. That also takes the resistor out of circuit and the solo-ed middle pickup will see the full 500K.

I think this should work. Does it sound ok for your purposes?

[David Ross David Ross Musical Instruments]

Hey Gerry, yes that should work fine! I’m wondering about the value of the resistor however, would it be a ~250k resistor to ground?

[Gerry Hayes Haze Guitars]

No. It needs to be around 500K to do the job (it’s a resistors in parallel thing). There’s no easily available 500K resistor so use a 470K instead. That will get you where you want to be well within regular pot tolerances.

[David Ross David Ross Musical Instruments]

Gotcha, thanks Gerry!

[Gerry Hayes Haze Guitars]

EDITED – THIS SHOULD HAVE BEEN REPLY TO MY COMMENT AT 11:44 ABOVE.

Hey Tony

Sorry. I’ve got a wrench to throw in the works. I’ve just seen that this PRS has 5-way switching (and some extra stuff) that allows both neck and bridge pickups be active together. This complicates things as it allows both of the new resistors be in circuit at the same time. I assumed it would be a Strat-type pickup selection that never has neck and bridge active together.

With both of these pickups active together, it drops the effective volume pot resistance to a very low 166K at that point.

We’d need to take one resistor out of circuit in position 3 to try make this work (while keeping it in circuit for the other positions). I’ve found the circuit for the PRS online but I’m not sure I have any easy solution right now.

[Gerry Hayes Haze Guitars]

EDITED – THIS SHOULD HAVE BEEN REPLY TO COMMENT AT 12:08

Ok, Tony. I think it should be possible to do but will probably require a SuperSwitch in place of the PRS blade switch. I don’t actually have pin-outs for that PRS switch but I think what we’re talking about here will need the extra poles of the SuperSwitch.

Fair warning, it’s all in my head right now and I may be wrong so, before I go too deep in working this out, is this extra hardware and modding something you and your customer are ok with?