Create a two stage potentiometer
Sometimes we find that a particular pickup (or pickups) are a little too bright for our guitars. Traditionally humbuckers are darker and manufacturers chose to use 500K potentiometers to ensure the pickup didn’t sound too dark or muddy. Single coil pickups in contrast sound quite a bit brighter, and manufacturers chose to use 250K potentiometers to tame the brightness.
These traditional potentiometer choices don’t always work with some pickups though. The Seymour Duncan JB was originally designed for use with 250K potentiometers. As a result some have found the JB to sound quite bright in many guitars that are equipped with 500K potentiometers.
Many guitars also come with a combination of single coil and humbucker pickups. Running a 500K potentiometer when using singles may make them too sharp and shrill. Sure you can have a couple of volume potentiometers, one for each sort of pickup. But what if you want to keep your control layout simple?
The solution is to make what I’m calling a two stage potentiometer. We only need a few things to make this: a 500K volume pot, a 470K or 510K resistor (you can’t get 500K ones), some wire, and a DPDT switch (double pole-double throw). To save on holes in your guitar or pickguard it’s probably best to use a push-pull or push-push volume pot. I didn’t have one handy, so to demonstrate I’m using a separate DPDT switch.
Roll your volume potentiometer completely counter-clockwise, and measure the two outer lugs with your multimeter set to read Ohms (2MOhms on my meter), and your potentiometer should be about 500K. You’ll be lucky if it’s exact, resistors and potentiometers are rarely to spec.
Do the same thing with your resistor. I used a 510K metal film resistor as they typically have far closer tolerances than carbon film ones. The combination of the potentiometer and resistor will get me close enough to a 250K reading for the second stage of my two stage potentiometer.
Cut two appropriate lengths of wire and solder them to the two middle lugs on your DPDT switch or push-pull potentiometer. This will be the bridge to the two outer lugs of your potentiometer.
Solder the resistor to the two lugs on one end of your switch or push-pull potentiometer. The two on the opposing side will be left alone, and will give you your default 500K setting.
Take the ends of the two wires and solder them to the the two outer lugs of your 500K potentiometer. Now you have a two stage 500K/250K potentiometer!
Test the potentiometer on your multimeter by attaching the probes to the two outer lugs of your potentiometer. One side of your switch will read around 500K, the other will be around 250K.
Wire your volume potentiometer in to your guitar as normal, and make the appropriate hole if you are using a separate DPDT switch, and you are ready to go. Overly bright pickups will no longer be an issue for you as you can quickly switch your potentiometer to suit almost anything.