Another weird alternative wiring question!

[Chuck]

Okay, time for another one - probably for Weirdy to solve! This time I’m looking at using two three-way slide switches to control a build with two P90s (trying to use bits I have in my spare parts box rather than buying new things!). What I would like to have is the following:

First switch
Up - neck pickup only
Middle - both pickups
Down - bridge pickup only

Second switch (I guess only active when first switch is in middle position)
Up - both pickups in parallel, in phase
Middle - both pickups in parallel, out of phase
Down - both pickups in series, like a humbucker

As usual I have no idea how to do this, but the following diagram does show me how to do the first switch set-up (my sliders have the same eight-pole setup). As far as the second switch goes, is there a way I can do what I want using a three-way slider? Of course I'm always open to other options of what I could do with the second switch ;-)

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[WeirdBits]

I'll work something up when I get a chance. I sketched out some options with that type of slider a while ago, so I should be able to dig them up as a point of reference.

[Chuck]

You are, as always, a legend!

[Simon Barden]

To switch phase you'd need the right type of P90. All the one's I've seen have the single core wiring with a braided screen (that is also the signal ground), so aren't suitable for phase switching. You'd need to find some that had two core wiring plus a separate screen.

For example, the Tonerider and IronGear P90 pickups both have the single core 'vintage braid' wiring.

What pickups did you plan on using?

[Chuck]

To switch phase you'd need the right type of P90. All the one's I've seen have the single core wiring with a braided screen (that is also the signal ground), so aren't suitable for phase switching. You'd need to find some that had two core wiring plus a separate screen.

For example, the Tonerider and IronGear P90 pickups both have the single core 'vintage braid' wiring.

What pickups did you plan on using?

At the moment I'm purely playing around with the standard ones that come with a PBG kit - which I'm assuming are not the right type ... I wasn't aware of the difference. I was going to just see how I went with them before contemplating any kind of pickup upgrade.

[Chuck]

Actually just thinking about this a bit more, I've read about people doing phase switching on Mustangs, and they're just a couple of strat single coil pickups. They're single core rather than two-core aren't they?

[Simon Barden]

From the PBG wiring diagram, it looks like the Pitbull P90 has a single-core plus screen cable (so similar but not quite the same as the vintage braid). So if you try and revere the phase of one, that means the screen will be carrying the signal, which is not a good idea. Also, it is very likely that the magnets and base plate will be connected to the shield, so all those parts will also be carrying the signal. A P90 is never the quietest of pickups, but this way round, it is going to be very noisy indeed!

You could probably dismantle a P90, and replace the cable with a 2-core plus screen cable. The screen gets connected to the baseplate (and by association the magnets and pole pieces), whilst the two core wires get attached to the two ends of the coil.

It's going to be fiddly, but it is possible. I'm struggling to find another make of P90 that doesn't have a screened single core cable, short of going for a custom order.

[Simon Barden]

However you may be able to switch in a filter circuit to get some different sounds with the pickups you've got. Weirdy might have some ideas there.

[WeirdBits]

Got some workable options sketched out, just need to draw them up on the PC.

[Chuck]

Got some workable options sketched out, just need to draw them up on the PC.

Thanks so much Weirdy - can't wait to see what you've come up with!

[WeirdBits]

Ok Chuck, as promised, here's a few diagrams… including something that probably fits in the specified 'weird alternative' category.

The are a couple of caveats with the pickup switching diagrams:
1. As Simon stated, ideally you need to separate the 'signal' +/- from the shield/ground on the pickup, and P90's typically have a hot core and a braid or bare shield carrying the 'negative' (but it depends on your pickup). The stock PBG P90's usually have a single hot core that connects to the + of the coil and the bare shield is split at the pickup end with one branch connecting to the coil - and the other branch soldered/screwed to the baseplate. In that situation it's actually not that difficult to convert it and connect a two core shielded cable so you've got your required signal separation. The good news is that this only has to be done to the neck pickup, the bridge pup doesn't need to be touched.

2. Doing parallel, out of phase and series switching using a DP3T switch involves a compromise as it really needs to be a 3 pole 3 throw to get all the connections you need. Basically, for the 'series' mode to function the pickup selector has to be set to the 'neck' position. If it's in the middle or bridge position when in series mode the neck pickup gets shorted out and you only get the bridge regardless.

This first diagram gives you the requested parallel, parallel out-of-phase, and series options:
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Diagram two is the 'weird alternative'… I'm calling it the SHoop Gambit. Instead of connecting the pickups in parallel out of phase, why not try Series Half out of Phase… like you can do with humbucker coils to get a pseudo single coil sound. Connecting two P90's in series would be sort-of like a big widely spaced fat humbucker, so I thought using a cap for the half-out-of-phase effect may give you an in-between sound. Some of the fatness of the series connection plus some of the nasally out of phase sound, but without the thinness you get in parallel mode. It's a little out there. I actually wired this up on my 1-string tester yesterday with a couple of P90s (Golden Age bridge and Tonerider neck) and it actually sounded quite nice - different but good and worth exploring. YMMV.
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Last diagram is just some tone filtering options. Left is is a single cap version giving both a hi cut and low cut, and the right has separate caps for each filter. Values around 0.0022/0.0033uF will probably give you the most usable sounds, but it's something you need to experiment with for your particular guitar and tastes. From my experience a low cut (cutting out the low end) using a 0.0033 works well, but 0.0022 may be needed to thin it out more. A hi cut with 0.0022 takes off just a bit of the highs, but you may want to go to 0.0033uF or even 0.0047 if you want it a little darker.
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(Note: there may have been some alcohol involved, so use at your own risk)

[Chuck]

Wow, thanks so much Scott - I so appreciate you doing this! Certainly gets me keen to fire up the soldering iron!!

Regarding separating the 'signal' +/- from the shield/ground on the pickup that you and Simon have raised, do I just connect one wire from the two-core to the "white" wire in the pic, and the other core is connected to the baseplate as the ground? In the picture you can see that on the PBG P90s I feel like I'm seeing the ground going to both the baseplate and also to the coil...

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[Simon Barden]

The shield wire in the picture is going to both the base plate and one end of the coil. You'd need a 2-core plus shield cable, One of the cores will go to the same end of the coil as the white cable, the other core would go to the other end of the coil which the shield is currently connected to. You are going to have to unwrap the tape around the coils to get to the joins. The shield then connects just to the baseplate.

[Chuck]

The shield wire in the picture is going to both the base plate and one end of the coil. You'd need a 2-core plus shield cable, One of the cores will go to the same end of the coil as the white cable, the other core would go to the other end of the coil which the shield is currently connected to. You are going to have to unwrap the tape around the coils to get to the joins. The shield then connects just to the baseplate.

Cool - thanks Simon, sounds both complicated and simple at the same time! I'll see if I can muddle through!

[WeirdBits]

The coil wires on these pickups are incredibly fragile and it's very easy to break them and/or the attachment points of the actual shielded cable. I'd actually suggest just snipping the existing single core shielded cable through the yellow casing ~5-10mm short of where it's stripped, then carefully separate the 3 parts (core, bare to coil, and bare to baseplate). Make sure you'll be able to insulate the bare to coil wire with heatshrink and, if you can, then attach some new 2-core shield wire. One core to each of the snipped coil wires and the shield to the baseplate.

I did this type of procedure on a PBG humbucker, snipping and attaching new cable, and it worked well. If you look carefully in this image you can see my new green wire is connecting to what was the original bare wire coil connection. I slipped some heatshrink over the original bare wire so it couldn't short with anything once it was all buttoned up.

http://www.pitbullguitars.com/wp-content/uploads/2014/01/86s19-PBG_humbucker_surgery_10.jpg

Topped off with more heatshrink before adding some more tape around the coils and sealing it up.
http://www.pitbullguitars.com/wp-content/uploads/2014/01/xa751-PBG_humbucker_surgery_11.jpg