How to Quickly Test Speaker Wires and Speaker Connections

The Battery Trick using a AA, AAA, or 9-Volt

A stripped pair of speaker wires
Touching a battery to stripped speaker wires lets you trace and test.

Here's a common problem – and a quick solution – with stereo and home theater systems. You've got a twisted pile of speaker wires on the floor, and you have no idea where they go and/or aren't completely sure which ends are for the right or left channels (not all speaker wires are nicely labeled). The most difficult and time-consuming way to sort this out is to untangle the wires one by one, following each length all the way back to the speaker(s).

And when you factor in having to navigate around all the power and/or connection cables to other pieces of equipment, this can turn into an all-day chore.

Thankfully, there's an easier, smarter way to trace the wires in a fraction of the time. All you need is a common household battery (fresh one preferred), such as a AA, AAA, or 9-volt (don't use anything bigger than these). While you're at it, grab some masking tape and a pen so you can label the wires as you go along. If you have speakers located in other rooms (particularly with whole house or multi-room audio systems), you might want an assistant to help you watch or listen. Be sure to turn off all equipment first, too.

Testing Speaker Wires with a Battery

Speakers, speaker wires, and batteries all have a plus (+) and minus (–) polarity. So what you'll want to do is pick up a speaker wire and hold one of its ends to one battery terminal (either + or –).

Now take the remaining wire end and repeatedly touch and disconnect it from the remaining battery terminal. This is best performed as a gentle brushing motion. If the speaker is working and connected properly, you'll hear a static and/or thump sound each time you brush the wire against the battery terminal.

Current from the battery causes movement in the speaker's drivers.

Now that you know which speaker you're working with, identify the correct polarities of the wire. Many speaker wires hare color-coded jackets and/or markings to show polarity. You want to make sure that the speaker is "in-phase" – all the positive and negative terminals match up – when connected to your stereo receiver/amplifier. While out-of-phase connections won't necessarily damage the speakers, in-phase ensures the absolute best performance.

If the wires don't provide any clues to polarity, you can figure out which is which by the way the speaker moves. Observe the cone each time you brush the wire against the battery. If the cone moves out then in, the polarity is correct. If the cone moves in then out, reverse the wires on the battery and test again. These movements can be very subtle (particularly smaller and/or high-frequency drivers), so good lighting and a keen eye will certainly help. This is also where having an assistant to brush wires against batteries will help save you time and effort. Take extra care if you bi-wire or bi-amp your speakers, since you have twice the connections to deal with.

Once you've identified the speaker and polarity of wires, use the masking tape and pen to label it for future reference.

You should also include the location (e.g. living room, bedroom, garage) and/or speaker channel (e.g. left, right, center, surround) on the label.

What to Do If You Don't Hear Anything

If you don't hear anything from a speaker, check the wire connections on the back of the speaker to make sure they're firmly set. Make sure you're using a fresh battery too – only briefly touch wires to the battery when testing, otherwise it can drain too quickly. If you still hear nothing, the problem may be a defective speaker and/or defective wire between the amplifier and the speaker.

Connect some known-working speaker wire to the unresponsive speaker.

If the battery trick still doesn't produce sound or movement of the speaker cones, then the speaker may be defective. You'll want to further investigate as if you're troubleshooting when one speaker channel isn't working. If the battery test does work, this likely means that the original wire is the problem. You'll have to carefully check the entire length of the wire in question, since even a small break can lead to problems.

If you're dealing with a subwoofer, there are a few additional steps to perform when trying to troubleshoot when your subwoofer isn't working. Subwoofers don't always connect the same way that typical stereo speakers do.

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