Wiring with 85/15 three wires, CTS PP pots and three way switch


New Member
Jun 28, 2016

I have begun to mod my PRS SE custom 24.
I've replaced the pickups by 85/15 Treble and bass; these have three colours wire (White/Red/Black).
I plan also to use two Push-Pull CTS pots to have both treble and bass humbuckers splitted.
I have placed a three way switch (those with 0 1 3 5/ 1 3 5 0 connections), as I prefer to simply know what each position is regarding pickups (Neck / both / bridge), and have the choice of pickup type (Hum/split) via the push-pulls.

I have plans to use small DPDT DIP switches in the cavity
- to be able to invert the Push-Pull position (to have the most used one set in pushed position, set once in the cavity of the body)
- to be able to choose between screw or slug sides of the pups when splitted (again set once in the cavity of the body).

I think I have a wiring diagram that is ok. My idea is to have all the time Hot and Ground connected (the Black and White from the pups), the red being disconnected in Humbucker mode, and connected in split mode. (RED -> CTS PP C1-> CTS PP 1/2 -> DPDT1 1/2 -> DPDT1 C1, such as a simple two way switch configuration, so depending on the DPDT settings, connection is achieved either in Push or Pull position).

Now to be able to define which side of the pup to 'listen to' in split mode, I was thinking simply to connect Red either to Ground or Hot (I assume electrically, when red and white or black are connected, this part of the pickup will produce nothing, right? Even if Black/White is connected). So to continue, DPDT1 C1 -> DPDT2 -> DPDT2 Ground/Hot.

I saw that sometimes, this connection to ground/hot is not 'complete' and is sometimes done with a resistor (values still to be found), hence keeping a part of this side of the pickups active. So DPDT2 -> R1 - Ground / R2 - Hot. I assume the values of R1/R2 would be fractions of the resistance I can read between Middle Red and Ground and Middle Red and Hot, right?

Now after some reading, I saw that something should/could be done with the CTS pots resistance. I have 500Kohms ones for volume and tone. Should I, in split mode, put resistors in parallel with the volume pot to level the output between humbuckers and split positions? I was thinking to use the second push-pull circuit (C2 -> 3/4) to connect a resistor in parallel with the pot in split mode. These resistors values to be still determined, but would amount when both pickups are splitted and resistors added in the circuit to obtain a 250Kohms pot. I calculate this with 1/250 = 1/500 + 1/R + 1/R, giving my 1Kohm for each resistor:

In 2 Humbuckers config, no resistors, 500Khoms volume pot
In 1 humbucker 1 split config, 1 resistor, 330Khoms volume pot
In 2 split config, 2 resistors, 250Kohms volume pot.

Is it required if the splitted configuration is done with a resistor to ground/hot, or in this case, the volume change is not that drastic and I can let the volume pot at 500Kohms all the time?

I see also sometimes a tiny cap (and resistor?) is put in parallel to the volume pot (treble bleed?) to darken less the sound at low volume? Any thoughts about this in this context?

So my aim is versatility and flexibility. Push-Pull pots would do the splitting for each pickups (with a DPDT switch inside the cavity to revert their positions according to usage) and maybe pilot a volume correction circuit. Screw/slug part used in split mode would be choosen also with a DPDT switch inside the cavity) maybe with a resistor circuit to save back a bit of the signal from the discarded side of the pickup, and the rest is currently suspended in the limbo (treble bleed circuit or not and its characteristics, Tone caps values (also maybe to vary depending on PP choice but I think I begin to lack switches here or maybe the second circuit of DPDT2 could play here, but would be set at the same time as the screw/slug settings?)

Can you help me on this?

I also found contradicting infos for the 85/15 three colours wires.
Is this correct:
85/15 treble (bridge): White Hot (++) / Red middle (+-) / Black Ground (--)
85/15 Bass (Neck): Black Hot (++) / Red middle (+-) / White Ground (--)

Hope this has not been discussed ad libitum already (I know, it has been ;-)).

All the best,

And a few more questions:

If I would simplify (scrape the DPDT stuff), what would be the best choice for split, screws or slugs? Or screws for neck, slugs for bridge, or the way around, or both slugs?

And what would be the resistors values to connect/nil between Red and Hot/Ground the dropped bobin?