Need assistance wiring a P-Rail into a Les Paul without switching potentiometers.

[Hiwatts and Gibsons]

Hi all, this is my second post and I joined here specifically to.ask this question.

I have a LP Studio which is currently housing a TV Jones Supertron in the neck and a vintage Gibson Tarback in the bridge I wired into it to replace the two Carvin pickups that were in it when I purchased it. While I love the Tarback I have in it the Tarback has separated from the mounting tabs, and I need to repair it. I also love P90's a bit more than humbuckers in the bridge and have a brand new P-Rail here so I want to swap them out the next time I restring it as well as replacing the old roller bridge with a new Schaler roller bridge.

My question is can I use the existing pots to do so? I plan on wiring the P90 coil of the P-Rail to be always on, then use the Tone control as a blender to progressively blend in the Rail coil in series for humbucker operation so that with the Tone control at 0 I have just the P90 coil in operation, but as I roll up the tone control it blends in the Rail coil in parallel.

First, how would I wire this up?

Second, will this provide authentic P90 tones when the tone control is at 0, and full parallel humbucker tones with the Tone control at 10.

Thank you for your time, and any help will be greatly appreciated.

 

[ehdwuld]

Seems like using a Triple Shot Ring (TS-1)
would be the better option

Choose
Both in series
Both in parallel
Just the P90
Just the Rail

 

[Hiwatts and Gibsons]

Thanks for the input, but I really don't intend on using the Rail coil or the Series mode. Tbt I could probably get by perfectly fine with just wiring it up with the P90 coil active. However I would not mind having the parallel humbucker option accessible, and I never use the Tone knob on my bridge pickups. If it is possible, then using it as a blender would probably give me a much wider palette of tones by progressively adding in the rail thanI would utilize regularly then the Triple Shot would. It should go from adding a little extra top end with the Rail coil partially added in to a nice hot PAFish tone with the Rail coil fully blended in.

 

[freefrog]

Below is my contribution.

Green and white to ground (with bare wire, not pictured). I've shown the white wire as a grey one, BTW (white on white wouldn't have worked, obviously).

Black to outer lug 1 of original volume pot of bridge PU (outer lug 3 being the grounded one). Center lug to switch.

Tone pot of bridge pickup changed in a volume control for the rail: no more capacitor, outer lug 3 to ground, outer lug 1 connected to the same outer lug 1 of the original volume pot, red wire to the center lug of this "converted" tone pot...

Should put the resistance of the former tone pot in parallel with the Rail. Pot at 0/10 = red and green wires altogether to ground. Rail totally disabled. Pot @ 10/10 puts the rail in parallel with the P90 side. Both coils see both 500k controls in parallel, giving an overall resistive load of 250k (which is the same overall load seen by an humbucker with a volume + a tone control).

Should work, so. And the converted tone pot will remain a tone control to some extent, since the sound will be warmer with the P90 alone than with both coils in parallel. ;-)

FWIW. HTH.

 

[freefrog]

5spice sim of resonant peaks with the "converted" tone pot from 0/10 to 10/10, through a 370pF cable plugged in a 1M input. P90 alone resonates @ 2.5khz. Coils in parallel, @ 3750hz approximatively... In this sim, the "converted" tone pot is linear. A log one won't/wouldn't have the same taper.

 

[ehdwuld]

Hmm could it be possible that just wiring it like two independent pickups

which may be wht freefrog has above

Black to the original volume
Red white pair to ground

Green to second volume (repurposed tone )

This would make them parallel when both on

you would have to wire the pots as independent pots
Or when one is off neither will sound

 

[freefrog]

Hmm could it be possible that just wiring it like two independent pickups

which may be wht freefrog has above

Black to the original volume
Red white pair to ground

Green to second volume (repurposed tone )

This would make them parallel when both on

you would have to wire the pots as independent pots
Or when one is off neither will sound

Excellent idea IMHO... And it also came to my mind this morning.

I just wouldn't put red and white to ground since it would put the two coils out of phase with each other, at least according to the official Duncan wiring (parallel signal path being shown in the 4th pic of the related page: ​https://www.seymourduncan.com/blog/latest-updates/the-p-rails-wiring-bible-part-2 ).

+1 about the possibility of independant volumes devoted to each coil, anyway. After all, it just requires to swap the black and output wires on the first volume pot, in order to put the output to switch on the outer lug 1 and the black wire of the P90 side on the center lug. Each coil would then have its own volume control without affecting the other...

 

[Hiwatts and Gibsons]

Below is my contribution.

Green and white to ground (with bare wire, not pictured). I've shown the white wire as a grey one, BTW (white on white wouldn't have worked, obviously).

Black to outer lug 1 of original volume pot of bridge PU (outer lug 3 being the grounded one). Center lug to switch.

Tone pot of bridge pickup changed in a volume control for the rail: no more capacitor, outer lug 3 to ground, outer lug 1 connected to the same outer lug 1 of the original volume pot, red wire to the center lug of this "converted" tone pot...

Should put the resistance of the former tone pot in parallel with the Rail. Pot at 0/10 = red and green wires altogether to ground. Rail totally disabled. Pot @ 10/10 puts the rail in parallel with the P90 side. Both coils see both 500k controls in parallel, giving an overall resistive load of 250k (which is the same overall load seen by an humbucker with a volume + a tone control).

Should work, so. And the converted tone pot will remain a tone control to some extent, since the sound will be warmer with the P90 alone than with both coils in parallel. ;-)

FWIW. HTH.

Thank you for that answeŕ. It just so happens I have an extra set of Allesandro 500K vintage taper pots I can swap in to replace the 300K pots that come stock in the LP.

 

[Hiwatts and Gibsons]

Excellent idea IMHO... And it also came to my mind this morning.

I just wouldn't put red and white to ground since it would put the two coils out of phase with each other, at least according to the official Duncan wiring (parallel signal path being shown in the 4th pic of the related page: ​https://www.seymourduncan.com/blog/latest-updates/the-p-rails-wiring-bible-part-2 ).

+1 about the possibility of independant volumes devoted to each coil, anyway. After all, it just requires to swap the black and output wires on the first volume pot, in order to put the output to switch on the outer lug 1 and the black wire of the P90 side on the center lug. Each coil would then have its own volume control without affecting the other...

Hey, thank you again. In this wiring scheme for the bridge pickup can you tell me exactly which wire goes to which lug on each pot, including the wire from the 3 way pickup selector switch?

 

[freefrog]

Hey, thank you again. In this wiring scheme for the bridge pickup can you tell me exactly which wire goes to which lug on each pot, including the wire from the 3 way pickup selector switch?

Here we go. 2d schematic, adapted from the previous one. Changed the hot wire going to the switch for a brown line, avoiding any confusion with the black wire from the PU...

 

[Hiwatts and Gibsons]

Here we go. 2d schematic, adapted from the previous one. Changed the hot wire going to the switch for a brown line, avoiding any confusion with the black wire from the PU...

Got it. The green and white go to the back of the original Vol pot with the bridge ground wire, the black wire to the center lug, the the switch and bridge wire to the left lug (1st?). The rail coil positive wire goes to the center lug of the original tone control with the bridge wire to the left lug (3rd?).

Thanks again.

 

[Hiwatts and Gibsons]

Here we go. 2d schematic, adapted from the previous one. Changed the hot wire going to the switch for a brown line, avoiding any confusion with the black wire from the PU...

Whoops, meant to say the wire bridging the "volune" pot to the "tone" pot goes to the right lug (3rd) on the diagram. Also it looks as though there is a second ground wire on the back of the pot going to the left (1st) lug.

 

[freefrog]

Also it looks as though there is a second ground wire on the back of the pot going to the left (1st) lug.

Both pots are wired exactly in the same way, with the center lug receiving the hot wire from a coil, the "1st" lug going to the switch and the "3rd" lug grounded. The 2d pot is just upside down compared to the other...

 

[ehdwuld]

Those volumes pots need to e grounded together

A single wire to the back of each

 

[freefrog]

Yes, of course, a ground bus between pots is necessary... can be a bare wire or something conductive between pots (metal plate holding the pots, adhesive shield)...

Not fully pictured in my botched schematics simply because such a grounding is necessarily already present in the guitar as it is (or the pots wouldn't work)... ;-)

 

[Artie]

Isn't this just the standard Duncan spin-a-split?

 

[freefrog]

Isn't this just the standard Duncan spin-a-split?

Not quite, since the goal was to have the coils in parallel with each other and not in series.

I wouldn't have botched these awful schematics otherwise...

 

[Artie]

Not quite, since the goal was to have the coils in parallel with each other and not in series.

I wouldn't have botched these awful schematics otherwise...

Yup. I see the confusion now:

I plan on wiring the P90 coil of the P-Rail to be always on, then use the Tone control as a blender to progressively blend in the Rail coil in series for humbucker operation so that with the Tone control at 0 I have just the P90 coil in operation, but as I roll up the tone control it blends in the Rail coil in parallel.

A bit of ambiguity here.


​

 

[freefrog]

I've seen the ambiguity. I've just decided to give the last word to the last words, so to speak. ;-)

Made sense to me when considering the sims that I've shared in post 5... and the guitar involved: with an inductance in the 11H range, a P-rails in series would be quite dark in a LP IMHO.

Now, if Hiwatt and Gibsons wants to try the series mode, he's free to use the spin-a-split recipe. Thx to have recalled it, Artie.

 

[Hiwatts and Gibsons]

Yup. I see the confusion now:



A bit of ambiguity here.


​

That's quite odd. I totally meant to type parallel in both sentences, and could swear I did so.