Schematic courtesy of singlecoil.com
Here’s a super-flexible mod for dual-humbucker guitars with 4-conductor pickup wiring. The 3-way pickup selector on most HH guitars offers three sounds, but by adding two DPDT mini-switches to the existing wiring, you can get eight switchable sounds. As shown in the schematic, one switch acts as a coil cut to go from humbucking to single-coil operation, and the other is a series/parallel switch to further expand the tonal palette. If the pickups have metal covers, like on a PAF-style humbucker, you’ll have to make sure they aren’t connected to the pickups’ common ground. More about this in a moment.
Installing two mini-switches is easy on instruments with a pickguard or control plate, but it can be a real pain on guitars that lack them, such as a Les Paul. In that case, I’d suggest using two push-pull or push-push pots. The DPDT switching matrix is standard on most switchable pots, so either way, it should be easy to adapt this mod to your specific guitar.
Now, about the metal pickup covers: Because of the series/parallel switch, we need to separate the pickup’s cover from its ground and then install a new ground wire exclusively for the cover. This is the same operation as modding a Telecaster with 4-conductor wiring, which I’ve covered here. Alternatively, you can simply remove the cover or swap it for a plastic one.
The payoff. On a typical dual-humbucker guitar, the 3-way pickup selector offers either bridge humbucker, neck humbucker, or both humbuckers in parallel. Thanks to the two DPDT switches, you get five additional sounds:
• Bridge single-coil
• Neck single-coil
• Both single-coils in parallel
• Both single-coils in series
• Both humbuckers in series
Operation. Essentially, the two new switches work as extensions of the pickup selector switch. For example, when you select the bridge humbucker with the 3-way switch and then hit the coil-split switch, you get the bridge single-coil. Or when you use the 3-way switch to select both humbuckers in parallel and then hit the series/parallel switch, you put the pickups in series, which really packs a punch. As an extra bonus, the wiring offers hum-free operation when the two single-coils are used together in series or parallel. (When using either the bridge or neck single-coil by itself, you face the same noise issues you would with a standard Strat or Tele—that’s the nature of the beast.)
To keep the schematic as simple as possible, I’ve ended right after the 3-way pickup selector switch—in other words, it doesn’t show any volume and tone pots. That’s because the mods all occur before the 3-way switch, so everything that comes after the pickup selector switch can stay exactly the way it is. This reduces the diagram to the necessary basics, which is convenient because after the 3-way switch a Les Paul is wired differently from, say, a PRS or Hamer.
I show the two switches as individual parts on the schematic. If you use a push-pull or push-push pot, the switch is located underneath the pot, but the wiring remains the same. As usual, I’ve used the Seymour Duncan color code for the wiring. If your pickups are from another company, simply transfer their color code to this diagram.
Stay tuned for our next project. Until then, keep on modding!