push pulls

[BigAl]

:cool: I'm thinking about rewiring my cu22 with two push pulls ,I was hoping to split either p/u or both at once....has anybody tried this out?? I tried out a yamaha which had something similar using two push/push.But since this type of switching is normally done on the tone controls I was worried that the value of the tone pot would not work as a volume control......make sense?????
cheers AllanB

[aleclee]

Most P/P pots have lousy tapers. You could use one for a volume control but if you don't get lucky with the taper, you're liable to be disappointed with the results.

[Jim Collins]

You can certainly do this, but you have to be careful about the push/pull pot you choose. The 500K/DPDT push/pull that is already in use as your tone control is okay for that function, but you might not like it as your volume control. The 500K value is correct, but these pots do not usually have the smoothest of tapers. A pot with a less than ideal taper is okay for a tone control, but many wouldn't care for it as a volume control. There is a pot available that has a SPST push/pull switch, instead of a DPDT, and these pots are supposed to have better tapers. (I think Gibson may use these things as the volume controls in the Jimmy Page LP.) It turns out that a SPST switch is all you need to cut a coil on a single pickup. Look for this pot on the Allparts website.

[Erik]

Listen to what Alec said...I have found it to be true more often than not.



Erik H

[BigAl]

Thanks for the quick reply...You confirmed my doubts....standard mcarty it is then.........cheers AllanB:( Most P/P pots have lousy tapers. You could use one for a volume control but if you don't get lucky with the taper, you're liable to be disappointed with the results.

[BigAl]

:) thanks again for the advice,,AllanB

[Andrew Chen]

You may want to look into getting one of the new Fender S1 switches. Fender is using these push-push pots as volume controls to split the humbuckers.

[PaulO]

John -

I was wondering if you had an Allparts part number for items I would need to rewire my PRS Custom 22 so that it matches the wiring of a McCarty? I like the McCarty push pull and single toggle switch idea. I understand PRS uses some sort of circuit board for wiring nowadays?

I could just go and trade in my CU22 for a McCarty, true, but then again it might be less expensive to rewire. True?

Thanks a bunch ....

Paul

[Jim Collins]

In the previous incarnation of BAM, I posted this in the technical archives. They didn't survive the move, so here it is, again.
Converting a rotary switch to McCarty wiring, using the existing pickups.

There will be some body modification required. The shaft of the rotary switch is narrower than the shaft of the toggle (assuming a Switchcraft toggle, like PRS uses). Take great care with this, or have someone experienced in woodworking tools do it for you. It is very easy to chip the finish on the guitar, and you only have the knurled nut to hide any goofs.

McCarty wiring also features a push/pull tone pot, as opposed to the standard tone pot that rotary switch guitars use. The shaft of the push/pull pot is narrower than the shaft of the regular pot, which means there will be room to spare in the hole, when you mount the push/pull pot. It is possible to center the pot in the hole, and tighten the nut, but you might have better success if you get a small piece of surgical tubing to put around the shaft of the push/pull pot.

The wiring of the neck pickup will be a little different from the wiring of the bridge pickup. The two pickups have opposing magnetic polarity. For the bridge pickup, the idea is to “move the ground” by pushing or pulling the tone pot. For the neck pickup, the idea is to “move the hot” by pushing or pulling the tone pot.

Let’s start by defining our environment. The push/pull pot has a DPDT (double pole, double throw) switch on its back. This switch has six lugs. The pot underneath it has three lugs. Face the pot so that the shaft is pointing away from you, and all nine lugs are facing you – as if it were mounted in the guitar, and you were looking in the control cavity.

We will name the three tone pot lugs P1, P2, and P3, from left to right.

The DPDT lugs will be named S1, S2, S3, S4, S5, and S6, with S1 being the top lug on the left, and S3 being the bottom lug on the left (closest to the pot casing). Similarly, S4 will be on the top right, and S6 will be on the bottom right (closest to the pot casing).

The volume pot lugs will be named V1, V2, and V3, from left to right, with the lugs facing you, and the shaft pointed down, as if it were mounted in the guitar, and you were looking in the control cavity.

The toggle switch has five lugs, assuming you use the Switchcraft toggle that PRS uses. With the shaft pointed away from you, and the lugs pointing toward you, you’ll see three lugs on top, and two on the bottom. These will be names T1, T2, T3, T4, and T5, from top left to bottom right. (If you are using a different switch, the switch may not have the same lug arrangement. It may only have four lugs. The lugs T4 and T5 will be jumpered together, as if they were one lug.)

When you remove the rotary switch from the guitar, you’ll see a red lead going to lug V1. Disconnect this lead from the rotary switch, but leave it connected to the volume pot. We’ll use it. (After all, you aren’t changing volume pots.)

The volume pot will also have a wire running from its casing to the casing of the tone pot. Disconnect this wire from the tone pot, but leave it connected to the volume pot casing. We’ll use it, also.

Bridge pickup. Black lead goes to T3. Red lead goes to S6. White lead goes to S4. Braided shield goes to ground (volume pot casing).

Neck pickup. Black lead goes to ground (volume pot casing). Red lead goes to S3. White lead goes to S1. Braided shield goes to volume pot casing.

Run a lead from S2 to T1.

Run a lead from S5 to ground (volume pot casing).

Run a lead from T2 to ground (volume pot casing). Lug T2 is an obvious ground lug on the toggle switch. It will not be connected to any other lug on the switch, regardless of the toggle switch setting.

Connect the existing lead from V1 to T4 and T5. (T4 and T5 are the output lugs from the toggle. Some toggle switches may have only one output lug.)

Connect a lead from V1 to P3.

Connect a .022uF capacitor between P2 and the tone pot casing. The chances are that the capacitor that was on the old tone pot was clipped too short to reuse. Get a new one. They are cheap.

Connect the existing wire from the volume pot casing to the tone pot casing.

That should do it.