Half out of phase pickup wiring question

paulnb57

Following on from my previous question about Stratty tones from Humbuckers, my Thinline Strat is routed for two humbuckers with a three way gibson type switch, it currenty sports 2x HB sized "P90's"

A suggestion was to do the half out of phase mod on my "P90's" (as used by Gerry Donahoe) to get a faux in between ish Strat sound that I crave.......

Could anyone be so kind as to scrawl a wiring diagram for me please, so I can give it a go?

Cheers!

Paul

CasperCaster

Firstly, apologies for the long post. The basic HOoP (Half Out-of-Phase) wiring is pretty simple if you don't mind an extra switch - it's just a standard phase switch modified with a capacitor as one of the jumpers, but this could be somewhat difficult depending on how your pickups are wired!

Firstly, if your HB sized P90's have metal covers, and are wired in classic Gibson style (single core wire with an outer braided shield connected to the pickup's baseplate and cover), this will first need to be modified. The reason for this is that you need to reverse the phase of one of the pickups (hence hot will become earth and vice versa), and having the case of the pickup connected to the hot side of the circuit would be very noisy, so at least one of your pickups (ideally the neck pickup) needs to be wired with two core wire with hot and earth signal wires and a separate shield.

With that sorted you will need a DPDT switch, either as a toggle switch or a replacement push/pull or push/push pot. Either way, you will have a DPDT switch (six terminals) to wire, and it is inserted between the neck pickup and the pickup selector switch. The DPDT switch is wired as a standard phase switch (see diagrams on the Duncan or Dimarzio websites) and the wiring looks something like a letter 'X'. The only exception that you need to implement is to substitute one of the jumpers (which makes up the 'X') with a 0.01uF capacitor - do this on the jumper which connects to the hot output from the DPDT switch. The hot and earth outputs from the DPDT switch go to the pickup selector switch and earth (typically back of a pot) respectively.

In use you will have two extra sounds, and if wired as suggested they will be as follows:
 - Firstly with both pickups on and the phase switch engaged you will have the HOoP sound you asked for. A normal out-of-phase sound is weak, thin and scratchy since anything sonically in common between the two pickups is cancelled. HOoP works because the capacitor blocks bass from the phase reversed neck pickup, so the bass from the bridge pickup is not cancelled when both pickups are combined (yes, I know that's counterintuitive).
 - Secondly, with the neck pickup on and the phase switch engaged you will have the neck pickup with some bass cut. Since the neck pickup alone is engaged, phase is not an issue, but the capacitor will still be in series with the pickup and will cut bass if the phase switch is engaged. This is also a useful trick for muddy neck humbuckers - just wire a capacitor in series with the neck pickup hot wire (typically a 0.047uF cap in that scenario).
 - Without the phase switch engaged your guitar will function as normal.

I hope this helps.

paulnb57

Thanks Casper!

normula1

The Donahue wiring also has a couple of resistors in there as well as the capacitor

For your guitar, it will look something like this. Obviously your pickup wiring colour scheme may vary

paulnb57

@normula1 awesome, thanks!

CasperCaster

@normula1 you are absolutely correct, the JD circuit does indeed include a couple of 6.2K resistors to finesse the effect, and your diagram is excellent. In fact your diagram is everything that I wish I could do - what did you use to produce it?

paulnb57

As the guitar in question is currently fitted with 2 HB size P90's could this wiring be adapted to try with them…is the switching necessary on the pot. Could the effect be permanent in the both pickups selected position on the 3 way switch?

Cheers!

normula1

I used Microsoft Visio with a stencil full of guitar basd components. I spend most of my day drawing design pictures using Visio in the IT industry so the one here was a quick 15 minute knock up

normula1

As long as one of your pickups has a three core cable (two cores plus the ground wire) then yes you can do it with your P90s.

You could also wire it permenantly to your three way, but when the neck pickup is selected by itself, you would probably have some bass roll off as the signal is coing via the capacitor. In fact the same would be true if the switch is in half out of phase mode on my original pic. In normal mode it would not be affected.

paulnb57

Thanks! I can follow a diagram, but just dont understand it!

CasperCaster

I've just looked at this again and I think I have to be the bearer of bad news - I think there is an error in the diagram prepared by @normula1. Sorry....

The JD wiring does incorporate two 6.2K resistors in the HOoP position. One is assigned to each pickup, but in the wiring diagram above they are both assigned to the neck pickup, being on both the +ve and -ve legs of the neck pickup as currently drawn. It is quite possible to incorporate a 6.2K resistor in series with the capacitor exactly as drawn on the red wire (it's the resistor on the black wire which is wrong). However, with a DPDT switch (i.e. a standard push/pull type pot) it is not possible to separately switch in a 6.2K resistor on the bridge pickup when HOoP is selected - a switch with more poles is required such as a Fender S1 switch (4PDT) or a small toggle switch.

So, you may have to use a more complicated switch and wiring or drop the resistors altogether. Perhaps try a quick and dirty test - wire the guitar with the neck pickup out of phase and with a capacitor in series with it. This will give three sounds:
-bridge pickup alone.
-bridge and neck together HOoP.
-neck pickup alone with bass cut.
If the HOoP sound is close to what you desire then it will be worth the investment of time and money to do it properly with an S1 or other multipole switch (and perhaps take the opportunity to try a variety of capacitor and resistor values to tweak the sound to match the P90 style pickups). Of course, if the HOoP sound is a long way from what you desire then ditch the idea completely and try something else. Sorry again!

normula1

Oops, yes you are quite right.