Saturday, September 30, 2023

Guitar Wiring - Phase Switch and Blend Pot

Half the fun of building a partscaster is to experiment with unique guitar circuitry. The first guitar that I made has been a platform for experimentation and the journey continues. A couple of things bugged me about the first iteration of this guitar's wiring, so I decided to try a couple of new idea.

One was to use a knob that changes the balance between the neck pickup and the bridge pickup. This is done using what's called a blend/balance potentiometer. In the middle position, there is no added resistance to either pickup, then when turned one way or the other there is added resistance (lower volume) from one of the two pickups.

The second idea, was to add a switch to provide an out-of-phase sound. The effect is to create a thinner brighter sound because some of the waveforms that come from the two pickups are canceling each other out. Perhaps the most famous example of out of phase pickups is in a guitar called Greeny. Here's the wiring diagram:

This was a fun experiment. Though after using this guitar for a while now, I find though that I rarely touch the blend pot, nor do I use the phase switch. The fact that the phase switch only effects the middle position when both pickups are on makes it a little limited. Also, if the blend pot isn't in the balanced center spot, the out of phase effect is greatly limited. Having a switch to brighten up the sound is still something I'm interested in and I'm wondering if putting in a high pass filter using a capacitor would be a more effective technique since it could apply to all pickup selection positions.