Questions about SD P-Rails and Wiring Options

[JackFawkes]

Hello everyone! 
Apologies in advance for the long post (my first).

I'm building my first solid body electric guitar this year and spent a lot of free time last year planning and reading; and of all the forums I read posts from, this one seemed the most knowledgeable in terms of empirical data and actual observed experimentation. It seems like most members on most forums answer questions based on a mix of tribal knowledge, tradition, and superstition 😅 

I'm no guitar god, just a hobbyist who plays to himself (and very occasionally with a couple friends) off and on over the years. I've always used an old MIM Stratocaster from the 90's, which has served me well; but the few times I've played a Jaguar I've really liked the shorter scale and additional slight curvature to the fretboard, so that's what I'm going to build. But I haven't been charmed by the rhythm circuit, so I'd like to do something different with all that switching real estate. (Also, I played with the PTB controls on an G&L with humbuckers once and though it was really neat!)

It'll be an HH configuration (swimming pool route in an MJT body) and I've got some Seymour Duncan P-Rails to fill it. I anticipate that I'll be using the P90's most of the time, followed by the humbuckers, and maybe the rails on rare occasion.
I don't like the look of the Triple Shots, so instead I'll use the upper-horn area to house two 3-way switches and one or two 2-way switches; and for the hexagonal plate I'll use a 3-way toggle and one or two 2-way switches. 

What I'm hoping to do is use the two 3-way switches on the upper-horn to intuitively select P90/HB/rail for each pickup, and then possibly use two 2-way switches on the upper horn to be able to select serial/parallel for each pickup in humbucker mode. 
The 3-way toggle on the hex plate will select neck/both/bridge pickups, and a 2-way switch could select serial/parallel when both pickups are selected. 
A second 2-way switch could theoretically fit on the hex plate too, if anyone has a good idea what to do with it?

So my questions are this:
1.) What are the general thoughts on the P-Rails? 
2.) Suggestions on running them the "normal" way (rails in) versus rotating one or both pickups (rails out)?
3.) Does the switching scheme described above sound rational/efficient? I don't know what it would look like diagrammed up, but if moving the serial/parallel selectors from the upper-horn to the hex plate would require less wires to be run through the body, please let me know!
4.) Which sounds more reasonable for controls with three knobs: master volume + master treble cut + master bass cut -OR- master volume + neck TBX (treble cut/bass cut) + bridge TBX (treble cut/bass cut)? I don't think I've ever seen Volume+TBX+TBX before, it was just a weird thought I had (not even sure if it's really viable). 
5.) Suggestions on potentiometer (and capacitor) values? (500K across the board for a PTB?) 
6.) Shield just the three control cavities? The whole thing? Copper foil or MG Chemicals spray (nickel, or copper+silver, or carbon)?

That's an incredibly long list! If this needs to be split out into separate posts, please let me know.
Also, if anyone wants to only respond to a couple of these items, PLEASE DO! Don't feel like you have to respond to each one to reply, I value all of your input.

Thank you all SO much!

Jack 

[newey]

jackfawkes-

Hello and Welcome to G-Nutz2!

I won't claim to have all the answers but I have some . . . And I'm switching the order around a bit to take the easier ones first.

6.) Shield just the three control cavities? The whole thing? Copper foil or MG Chemicals spray (nickel, or copper+silver, or carbon)?

The pickup cavities are the most critical to shield, but my philosophy is, if you're going to have the whole shebang torn apart anyway, might as well shield everything. The control cavities are unlikely to be a source of significant noise, but I'm not going to tell you it can't happen. So, do it all and do it right just to err on the side of caution.

People who have used the shielding paint have claimed good results with it, but it takes a few coats. I'm a big fan of the copper shielding tape with the conductive adhesive. It's pricier than some other options but does a good job and so long as you overlap the pieces, you don't have to worry about continuity across your shielding, it's all connected via the adhesive.

1.) What are the general thoughts on the P-Rails?

We've had several people post wiring schemes for the P-rails, but I don't recall any actually being built, nor can I recall anyone reviewing the pickups. The theory of the thing sounds intriguing- two entirely dissimilar coils mated into a humbucker. I'm not personally a big fan of rail-type pickups; if they made a "P-Strat" humbucker, I'd be more interested. Certainly, though, the dissimilar coils makes for a lot of possibilities with splitting the coils, series/parallel as you have done.

3.) Does the switching scheme described above sound rational/efficient? I don't know what it would look like diagrammed up, but if moving the serial/parallel selectors from the upper-horn to the hex plate would require less wires to be run through the body, please let me know

!

It sounds rational, but perhaps a bit inefficient. You don't like the look of the Triple Shot™ rings, but the way they are wired is less involved than what you have, and gives the same options. The two switches on the rings are wired in what we call a "binary tree" arrangement- Both switches in one direction gives series HB, both switches in the other direction gives parallel HB, one switch to right, one to left gives the P90, opposite gives the rail coil alone. So, you get all 4 options with 2 DPDT On-On switches, instead of a 3-way and a 2-way. The triple shot scheme could easily be adapted to 2 toggle switches or slide switches, wherever you decide to put them. Of course, if you're looking to reuse the existing switches, that will limit the options.

As for location, if it were my guitar, I'd put the switches to control one pickup (however wired) on the lower bout, and the other pickup controls on the upper bout. The 3-way pickup slector could go either place, along with a global series/parallel switch as you suggest.

4.) Which sounds more reasonable for controls with three knobs: master volume + master treble cut + master bass cut -OR- master volume + neck TBX (treble cut/bass cut) + bridge TBX (treble cut/bass cut)?

The first option. With separate TBX pots for each pickup feeding into a master volume, you'll have interaction between the two TBX pots. Some of that could be alleviated by using a dual-gang volume pot, but you'll still have some interaction when both pickups are on. And, if you want to have that global series/parallel switch you mentioned, the dual TBX pots are going to present challenges with the pickups in series.

2.) Suggestions on running them the "normal" way (rails in) versus rotating one or both pickups (rails out)?

A matter of personal preference, but you said you'd mostly be using the P-90 coils. If so, I'd want the P-90s to the outsides, so that the bridge pickup gave me the more treble tone for leads, and the opposite on the neck, more jazzy-bassy sounding- IOW, max variation between the 2 coils I'd be using the most.

Pot values and cap values are also personal preferences, but 500K for the pots is certainly reasonable (and standard) given that, after all is said and done, these are two humbuckers.

[JackFawkes]

Thanks for the response newey ! 

Great, I'll plan on shielding the entire thing then. I've seen a lot of rave reviews of the MG Chemicals sprays, the nickel seems to be the most commonly used on guitars and basses; it usually seems to land around 5-8 ohms across an entire cavity after just one coat, and 1-2 ohms with two coats. 
What about the pickguard? I don't think I've ever observed a consensus on aluminum foil versus copper foil for the pickguard. Thoughts? 

I think I found one or two old reviews of P-Rails here when I was looking last year... I think antigua was one of them, and if I'm not mistaken, their creator frankfalbo used to post here too.

Hmm... so on top of not liking the look of the Triple Shots, my simple mind finds that switching scheme incredibly unintuitive.
For example, I'm unfortunately the kind of guy that absolutely cannot figure out/remember how to operate pedals like the Boss 200 and 500 series... I'm bad enough at playing guitar that I can't possibly also remember what morse code I need to tap with my foot to switch/select/save different presets at the same time.  
A 3-way and a 2-way for each pickup just seems so elegant to me. I'd only have to cry once when wiring it, instead of every time I want to change pickup settings 😅

The global series/parallel switch just sounded like it might be fun, but for all I know it might sound terrible with these pickups... I'm not even sure if a series/parallel switch is even worth having for the pickups themselves, which is one of the reasons why I was hoping to hear from some people that've used them.

Thanks for answering my weird Vol-TBX-TBX question. It was a neat to imagine, but being such a novice I forgot about (or rather, don't properly understand) complicated things like pickup loading and how different controls can interact with each other. PTB it is!

That's good feedback on the pickup orientation too. Yeah, 500K pots sounded like they might be a good call for both the P90s and HBs. 

Thanks again for the advice! I'm excited to hear what anyone else thinks about the P-Rails.

[newey]

You certainly can have the switching the way you want it (at least, I think you can, we haven't put pen to paper yet, but I can't see why it shouldn't be possible as you describe it). With guitars equipped with regular HBs with similar coils, I'm a big fan of the parallel HB as opposed to splitting the coils. But the P-rails are a different animal, the whole point is being able to have the individual coils. But I'd want the parallel HB option as well.

The global series/parallel? Many players aren't fond of putting 2 HBs in series as it can sound a bit "muddy". But again, these aren't regular HBs so who knows?

[FireBall]

I have the P-Rails in a tele body guitar. I use a 3 way switch and two DPDT knobs. Great pickups and lots of variety of sounds.

[FireBall]

I forgot how to post a picture.. 😂

[newey]

FireBall-

Welcome back! It's been a dozen years or so, good to hear from you again!

JackFawkes- sorry to hijack your thread but fireball is a long-time member who we haven't heard from in quite a while. A great guitarist (and one who has a nice Tele to boot . . .)

[FireBall]

Hey Newey, yeah its been a very long time! I'm attaching the headstock pic of my tele ...





I will try to answer more of the OPs question on the P-Rails. I use the DPDT and 3 way.. I can get HB N&B, P90 N&B, Hot Rails N&B and also OOP HB N&B. The last band I was in did a lot of cover songs from all genres.. I could find about any type of sound needed. The bridge HB is dark, which I love because I'm old school rocker.. . I would recommend any switching combo you want that unlocks all the versatility you can get for these PUs.

[stevewf]

I've got a pair of P-Rails in an LP style instrument. They're in Triple Shot™ rings, plus some other control mods, including:

1. one push/pull that switches the two pickups between series and parallel
2. another push/pull that swaps the phase of the bridge P-Rail
3. yet another push/pull for switching tone caps

The pickups are mounted as suggested by SD: with the P-90s on the outside, and with the Triple Shot switches also as suggested by SD (both switches toward bridge = P-90; this pertains to both pickups).

1.) What are the general thoughts on the P-Rails?

Since I have yet to play real P-90s and the same for rail pickups, I can't compare them to the normal kind of coils, so I can only comment on the P-Rails themselves:

• When in humbucker mode, the hum is substantially reduced compared to the single-coil mode. I'm talking about one pickup at a time here.
• That being said, they also drastically reduce hum when used a pair of single coil pickups (now I'm talking about two pickups at a time, using both P-90 or both rail).
• Surprisingly (to me), each pickup in HB mode also reduces the hum a lot. So the little rail's hum is about equal to the big P-90's anti-hum.
• That last point is born out when I use one pickup's rail plus the other's P-90 with the bridge pickup's phase swapped - hum is cancelled. Naturally, without swapping phase, there's a lot of hum.

There is definitely a difference in the sound when comparing the big P-90 coil against the small rail coil. I'm guessing that the difference would be predictable by someone who's familiar with each of those types of coil. More low-end in the P-90.

2.) Suggestions on running them the "normal" way (rails in) versus rotating one or both pickups (rails out)?

newey's comment about phase reversal is interesting. I haven't tried rotating either of the pickups, so I can't comment on the sound difference.

But a note on intuitive switch layout: either way, there's a counter-intuitive aspect. The Seymor Duncan way has you sliding both mini switches toward the bridge to get that pickup's P-90 alone (this pertains to both bridge and neck pickups). On the bridge pickup, it makes sense: slide the switches toward the coil you wanna hear; but it's the opposite for the neck pickup: slide the switches away from the coil you wanna hear.

On the other hand, if I were to swap the switch directions in the neck's Triple Shot, then I'd be sliding the bridge's switches one direction and the neck's in the other direction for a pair of P-90's, IOW opposite directions for the the same type of coil. Even if you rotate one of the pickups, then it's either sliding toward+away for like-style coils or slide opposite directions for like-style coils. Damned if you do...

5.) Suggestions on potentiometer (and capacitor) values? (500K across the board for a PTB?) 

I've seen suggestions to use a 360KΩ pot for P-90s, and 250KΩ for smaller single coils, and 500KΩ for humbuckers. Soooo... should we add poles to our switches for swapping resistors? I didn't go that far, since their's no room in the tiny Triple Shots.

I did, as mentioned, include a way to switch tone caps from .022µF to .047µF. As it turns out, I almost never use that switch. In a do-over, I'd skip it, or if really fussed, I'd pull up to shunt straight through a .022µF, and have the pot control a .047µF or .056µF (it'd be like pulling up makes the "10" like "0" and you can roll off even more).

[stevewf]

Oh yes, I forgot to comment on P-Rails in series. We're talking about the two pickups in series, not two coils within one pickup.

My LP has P-Rails that I can put in series. The pickups are mounted in Seymour Dumcan's Triple Shot rings.

As newey mentioned, there are some configurations that may be difficult to find useful, e.g. all four coils in series. Also, both P-90s in series can be muddy. Really, only when I've got at most one P-90 active is it useful to put 'em in series. And since I don't like hum, that means either a pair of rails, or a rail out of phase with a P-90. In those configs, yes, series is ok, and actually can be useful IMO.

[edit] Oops, I forgot: also each pickup with its coils in parallel, then the pickups in series with each other is ok too.

[JackFawkes]

Thank you all SO much for all your replies and insight!

Below is my first attempt at designing the wiring for this project. 
(should this be a new post in the Guitar Wiring section?)

PLEASE SCRUTINIZE IT AS MUCH AS POSSIBLE!
(seriously, I have NO idea what I'm doing; this is just my best guesses cobbling different pieces together )


I'm currently rereading through all the PTB-related board posts again right now to make sure I (hopefully) replicate the controls section properly. 

Thanks again everyone! 

[MattB]

Your diagram looks fine to me.

[newey]

JackFawkes-

You might get more responses with a new thread in Wiring, but I'll leave that up to you. We have strayed a bit from the topic, but I'm not going to "slice 'n dice" things since we've come this far anyway.

[JackFawkes]

Sounds good! 

I've posted my second draft in Guitar Wiring as Please Review: Series/Parallel/North/South + PTB Wiring 


Jack