How To Check The Phase Of A Pickup

Written by
David Shepherd
Published on
January 22, 2021 12:02:21 PM PST January 22, 2021 12:02:21 PM PSTnd, January 22, 2021 12:02:21 PM PST

Welcome back tech heads! For this week’s Fix It Friday, we’re going to demonstrate how to check the phase of your pickups. It’s quick, it’s easy, and it only requires two tools. 

Before we get started, some of you may be wondering: What does phase mean as it pertains to guitar and bass pickups? Without getting into the confusing textbook definition, phase is simply the direction of the electrical current through the pickup coil. This is determined by the pickup’s wind direction, magnetic polarity, and which end of the coil is connected to ground or hot. 

Why is this important? When pickups are out of phase with each other, you will notice a very thin and weak sound. The typical notion is that you want your pickups to be in phase with one another, as this allows for the intended tone of the pickups to shine through. Some people wire pickups out of phase intentionally in an effort to achieve a specific sound, but generally you want the pickups to be in phase with each other. 

Have you ever installed a pickup only to find out after all of the time you’ve wasted it’s out of phase with the other pickup? This can be very frustrating especially on guitars where swapping pickups isn’t easy. Not to mention it can be a major loss of revenue for a busy shop to uninstall and reinstall more than once! This, of course, can be prevented by quickly testing the phase of each pickup before installing them, saving you a ton of time and a monster headache. At Mojotone we test the phase of every pickup we build to ensure they are all built to the exact same phase; a practice of quality control.

I promised this procedure would only require two tools, and I meant it. Here’s what you’ll need:  

  • Multimeter
  • Large Diameter Magnetic Steel Screwdriver

Let’s get started! First, set the multimeter to ohms and hook the multimeter’s probes to the pickup leads. Be sure to hook the red probe from the meter to the positive pickup lead, and hook the black probe to the negative lead. You should be getting a reading (this will vary from pickup to pickup). See Image 2A below. 

Now we are ready to perform the phase test. To check the phase of the pickup, you will place the steel shank of the screwdriver across all of the polepieces on one coil. The shank of the screwdriver should magnetize itself to the poles (Image 3A). 

Now we need to pull the screwdriver away from the polepieces very quickly. You should notice that the ohms reading on your multimeter either jumps up or down quickly. Repeat this process if need be to make certain of whether the reading jumps up or down, and make note of it (Images 4A and 5A). 

Once you’ve done the first pickup, you’ll need to repeat this process with the next pickup and make note of whether the ohms reading on your multimeter jumps up or down when you pull the screwdriver way from the polepieces.

If all of the pickups meter up or if they all meter down, your pickups are in phase with each other. If one meters up and the other meters down, then they are out of phase with each other. The meter going up or down signifies which direction the current is flowing through the coil, and pulling the screwdriver away generates the electrical current through the coil so we can “see” which direction it is flowing.

That’s it! Can you believe how easy that was? I told you it was quick, and I wasn’t lying! Now that you know how to test the phase of a pickup, you can use this for quality control when building pickups, or when determining if any pickup being installed will “play nice” with the other pickup. If you are lucky, you can reverse the phase of one of the pickups; if the leads are reversible or if you have multi conductor leads. Knowing before you install can help you plan your attack and optimize your time and effort. 

We hope you enjoyed today’s lesson. See you next time!