How to Test for Speaker Wire Polarity

It’s important to have the correct speaker wire polarity in order to obtain the best sound from your speakers. Failure to do so will give lower quality sound. There are commercial devices to check for speaker wire polarity, but you can do it yourself without spending extra money.

Step 1 - Set Up

Begin by unplugging your stereo system at the outlet. You should also remove any wires that connect the stereo system to other devices, such as a television. Disconnect the wires of one speaker from the receiver. You will also need to remove the cover on the front of the speaker so you can see the speaker cone.

Step 2 - Speaker Cone

You won’t always be able to see the speaker cones, as not all speaker covers are removable, and that’s particularly true with a subwoofer. If this is the case, you need to position the speaker so you can see through the grille to view the speaker cones. It makes the task a little harder, but far from impossible.

Step 3 - Battery

Take out a 9 volt battery. Make sure that it’s fully charged, so always use a new battery for this. Take the speaker wires and wrap one around each of the terminals on the battery.

You now need to look at the speakers cones. The current from the battery will cause movement in them and you need to see which way the movement goes. This can be hard to distinguish immediately. The speaker cone should move out and then in. If it does this then the polarity is correct. If the movement is inward first, swap the wires around on the battery and look again. The movement should be outward first, showing you have the proper polarity. You can then connect the speaker wires to the receiver, with the wire from the positive terminal on the battery going into the red colored terminal on the receiver and the negative going to the black colored terminal.

Step 4 - Multimeter

To check speaker wire polarity with a multimeter, remove the speaker wires from both speaker and receiver. Set up the speaker wire so one wires is wrapped around each terminal of the battery.

Set the multimeter up to measure DC voltage. Touch the speaker wires to the probes on the multimeter. You’ll see a negative reading if the wire from the negative battery terminal touches the positive probe on the multimeter. This will allow you to mark which wire is which and to be able to connect positive to positive-red to red-and the negative-black to black.

You do need a current in order to measure, so having the battery is vital. You also need to be sire that you don’t measure from the receiver. The simplest way is just to use the speaker and the battery. Listen to the speakers after you’ve established the correct polarity and you’ll be able to readily hear the difference.