This guitar pickup phase tester is a small and very useful device for finding out how to wire an unknown single pickup or a humbucker to your guitar or a bass guitar. Usually, most companies like Seymour Duncan or DiMarzio who produce pickups have a manual showing how to connect the wires, but most stock guitar pickups or any unknown pickup are a mystery and need to be identified somehow. Four-wire humbuckers have to be figured out and it takes a lot of time for most of us to solder and test. The phase of the stock guitar pickups has to be determined before changing one of the pickups for matching the pickup phase and so on.

Using this tester you can quickly test any pickup!

Intended/Purposely built for testing and finding the phase of any pickup, this tester can also be used to verify that the input and output phases of each guitar or bass effect are the same. They should be the same. Usually, we do not care about this, but there are some exceptions. If a stompbox is fed into an amplifier’s send-return and it has a potentiometer to mix the wet and dry send-return signal, it’s important to have matching input and output phases, otherwise the signal from this pedal will be weak /out of phase/.

The unit has an idle current consumption of under 100uA and it works with a CR2032 battery. Since the current consumption is so low, a single battery should last for years. The unit starts only when a mono jack is inserted. To save battery life, unplug the jack.

Testing a pickup: You can use a short ¼” mono jack patch cable or an easy to be made ¼” mono with two alligator clips.1. Hold the wires to the mono jack with your hand or grip the wires with the alligator clips. For the first test, it is not important how to connect the wires. 2. Tap on the top of the pickup where the pole place slugs or screws usually are with a sharp Olfa style cutter or a flat screwdriver.

3. Watch the LEDs and check which one turns on first. This indicates the phase of the pickup. Ignore the second LED if it starts after a while. The first led to turn on indicates the right phase! If the indicated phase is reversed compared to the phase of your stock guitar pickups, just reverse the wires. The wire connected to the patch cable ground has to be soldered to the ground in your guitar. Solder the other one – the hot wire which was connected to the tip – to the pickup selector switch.

Determine the wires of an unknown 4 wire humbucker:  To determine how to use/connect an unknown 4 wire pickup, you can use almost the same procedure as testing a pickup. Usually, the cables have different colors, so you have to start somehow. 1. Take one cable and connect it to the ground of the patch cable. Short the remaining 3 cables by twisting their copper wires together and connect them to the tip (hot).2. Tap the top surface of the pickup with a sharp cutter to find which is the active portion of the humbucker. Some pickups have cover, so divide the pickup visually into two and tap around the top or the bottom half of the humbucker until you see LED activity. Now you have identified half of the pickup by the pin connected to the ground and a hot which is one of the 3 remaining wires.3. Start disconnecting wires connected to the tip (hot) one by one followed by tapping the pickup until the LED activity is gone4. Remember which wire was removed before the LED activity was gone. This wire plus the wire connected to the ground are the two wires from the half of the humbucker.5. Identify the phase finding a normal phase between these two wires.6. Repeat the procedure for the second half of the pickup and draw a sketch showing the cables going out of each portion of the humbucker with the right phase.

Testing a guitar effects pedal phase: For this test, you have to use a battery. You could use any AA, AAA battery, or any coin cell battery like CR2032. You need one battery, a short ¼” mono patch cable, and a custom ¼” mono cable with two crocodiles.1. Turn on the effect and put all control knobs to 12 O’clock (middle position).2. Connect the patch cable between the output of the pedal and the guitar pickup phase tester.3. Connect the crocodile cable to the input of the tested guitar effect. Connect the black (ground) wire to the negative battery terminal.4. Tap the tip (hot) alligator clip to the positive battery terminal and watch the phase. The green led indicates that the input and the output are in phase and you can put this effect into the send-return of your amplifier.

Specifications: PCB size: 48x21mmBattery: CR2032 (not included) Idle current consumption: under 100uA