How to wire partial-tap resistors in 5-way rotary selector

J

jeffrey kaplan

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Dec 31, 2018
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howdy,
this is my first post. i'm disappointed in the volume of the split-coil settings on my newly acquired 2002 CE. it has dragon II pickups and the 5-way rotary selector switch. i'd like to try adding resistors to increase the volume a bit on the split coil settings. i have seen many posts on doing this but not for a 5-way PRS rotary selector. i'm fine with wiring diagrams. can anyone give me the specific points to add the resistors between?

since it's my first post i can't add a link to the wiring diagram but it is in the support section at support>schematics>5-Way Rotary - Custom/Standard 22 & 24 - Pre-2007

thanks in advance for any advice on where to wire the resistors.
 
I'm a little confused. It's my understanding that the 5-way wirings give various combinations of coils (some of which are in parallel rather than series) but doesn't ever give you just one coil by itself, which is the situation the resistor wiring was designed to beef up.

I know the 5-way wiring has had at least three different configurations over the years (possibly more than that) so I may be wrong. But the 5-way on my '87 always has two coils active, and the 5-way on my '95 CE does also, though the '#2 position is distinctly different on the '95 compared to the '87. Now it may be that some more recent 5-ways do involve using one coil by itself, but I'm not sure of that.

Is it a factory 5-way that you're certain is wired correctly? And if so, is it possible that what you're hearing are parallel positions rather than full split? The 2 and 4 positions on my CE are a bit lower than the 1 & 5, but they aren't seriously weak the way half a humbucker would be.

This is the 5-way configuration for my "87:
pos1 - bridge pickup
pos 2 - both pickups, out of phase
pos 3 - both pickups
pos 4 - "Strat" - inner coils parallel
pos 5 - neck pickup

and the 5-way configuration for my '95:
pos1 - bridge pickup
pos 2 - "deep & clear" - outer coils parallel
pos 3 - “warm version of the in-between bridge & middle pickups” - inner coils in series
pos 4 - “crisp version of the in-between the treble & middle pickups” - inner coils parallel
pos 5 - neck pickup
 
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ah, ok. thx. yes, it's the volume of the #2 and #4 position that is weaker than i would like.
so if i use the 4 pole i could still have the split-coil sound but use resistors to better balance the volumes? if so can you point me to a link to one at stewmac and a wiring diagram for that?

thank you for the information. much appreciated.
 
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jeffrey kaplan said:
ah, ok. thx. yes, it's the volume of the #2 and #4 position that is weaker than i would like.
so if i use the 4 pole i could still have the split-coil sound but use resistors to better balance the volumes? if so can you point me to a link to one at stewmac and a wiring diagram for that?

thank you for the information. much appreciated.
Click to expand...

https://www.stewmac.com/Pickups_and_Electronics/Components_and_Parts/Switches/Rotary_Switches.html

It would take some thinking and a custom wiring schematic to change the function of positions 2 and 4.
 
heh, i understand. i guess if i can sort through that diagram the only question is what points to add the resistors to have less signal go to th ground.
 
Well, you would need to run the resistors out from the switch for positions 2 and 4 instead of just connecting to the common hot/ground.

Now that I think of it though, off the top of my head I'm not sure you would still be able to do the split series setting in position 3.

Depending on how attached to that you are, I think I have a super switch diagram that has both humbuckers in position 3, but with inside/outside for positions 2 and 4. You could adapt that to the rotary pretty easily.
 
Actually, you know what, you could probably just put the resistors in series with the coil split wires on the way into the switch. In other words, unsolder the coil split wire from the switch, solder the resistor to the pickup wire, then solder the other end of the resistor into the switch.

Still not sure what that will do to position 3, but worth a try to see what happens.
 
yes, would very much like to see the diagram to have both humbuckers in pos 3.
you're very generous with your thoughts and information. really appreciated.
 
Would you be open to changing the tone to a push pull for splitting both pickups, then using position 1 / 5 for the split sound?
 
shimmilou said:
Can’t defy the laws of electronics. In other words, adding resistance will lower the output, not increase it.
Click to expand...

You have it backwards. Electricity always wants to get back to ground, so the lower the resistance, the more signal that does not pass to the rest of the signal chain. In regular split wiring, the split coil has zero resistance. Putting a resistor in series with that coil allows a little bit of signal to bypass ground, which gives more output and fuller tone.
 
garrett said:
You have it backwards. Electricity always wants to get back to ground, so the lower the resistance, the more signal that does not pass to the rest of the signal chain. In regular split wiring, the split coil has zero resistance. Putting a resistor in series with that coil allows a little bit of signal to bypass ground, which gives more output and fuller tone.
Click to expand...

lol, i think i see what you are getting at, albeit a bit convoluted. You seem to mean not completely shorting one coil, as is done on some prs models, when coil splitting? in that case, i see what you mean.

Btw, electrons come from “ground”, flowing toward a more positive point, they actually want to get out of ground, but i get what i think you are saying, and you are correct, a bit more output. ;)
 
shimmilou said:
lol, i think i see what you are getting at, albeit a bit convoluted. You seem to mean not completely shorting one coil, as is done on some prs models, when coil splitting? in that case, i see what you mean.

Btw, electrons come from “ground”, flowing toward a more positive point, they actually want to get out of ground, but i get what i think you are saying, and you are correct, a bit more output. ;)
Click to expand...

Oh yeah, I'm definitely far from an electrical engineer. I think of those little electrons starting from ground, and we force them along a conduit to make noises with them, yet they seem to take any opportunity to return to ground. I guess they go where we tell them to, really.

Aaanyway, yeah we're on the same page about the splits. Using series resistors to prevent the coil from completely shorting.
 
This is probably what you have.

"5 Position Rotary"
1: Treble pickup
2: Outside coils - parallel
3: Series single coils
4: Parallel single coils
5: Bass pickup

The wiring diagram you referenced, doesn't show the internal switch connections, but it seems that you won't be able to do what you want with the current rotary switch. https://www.prsguitars.com/documents/prs_custom5wayrotary_pre_2007.pdf

You just might have to use a different switch, and add a push-pull pot for splitting. The resistor(s) can be easily added via the push-pull pot.

The easiest way might be to change the rotary to a three-way toggle, and change the tone pot to a push-pull, and then wire it in a more conventional manner, similar to a modern CU 24 with a three-way.
 
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