Speaker Phase Test

Catch reversed speaker wiring by ear: compare in-phase and out-of-phase tones at 100 Hz or 1 kHz.

In phase: should sound centered, solid, full bass

Ready

Frequency

Phase

Volume

Turn your system volume down first

Start at a low volume, especially with headphones and low bass tones, then raise it slowly.

Tip: if Out of phase sounds fuller, one speaker is wired reversed — swap +/− on that one speaker only. On mono devices both settings sound nearly identical, so this test does not apply there.

This tool runs locally in your browser — no audio is uploaded.

How to use

  1. 1

    Sit between the speakers

    The test works best on the listening axis, at equal distance from both speakers, at a moderate volume. Play the phase tone at 100 Hz first.

  2. 2

    Switch between In phase and Out of phase

    In phase, the tone should sound centered, solid, and full. Out of phase, it turns thin, hollow, and the bass almost vanishes.

  3. 3

    Interpret the result

    If Out of phase sounds stronger and fuller than In phase, one of your speakers is wired with reversed polarity — swap the + and − on one speaker only.

How it works & limits

Both speakers play the same sine tone. In phase, their waves arrive aligned and add up, especially in the bass. Out of phase, the right channel is polarity-inverted (multiplied by −1, equivalent to a 180° shift for a sine), so the waves cancel and the sound loses body and center.

Cancellation depends on both speakers being roughly equidistant from you and on true stereo playback. On a mono device, or a single-speaker Bluetooth system, the two versions may sound nearly identical — the test then says nothing about your wiring. Use headphones on the channel test page to verify your chain is stereo first.

FAQ

What is the difference between phase and polarity?

In everyday speaker work they are used interchangeably: one driver wired backwards is "out of phase". Strictly, polarity is the 180° flip tested here, while phase also covers timing differences from unequal distances.

Why does the bass disappear when out of phase?

Low frequencies have long wavelengths, so an inverted signal cancels strongly when both speakers play together. Above roughly 300 Hz the effect gets harder to hear, which is why the test uses 100 Hz.

I hear no difference — what is wrong?

Check that you are in stereo (not a mono Bluetooth speaker), sit between the speakers, and use the 100 Hz tone. If a subwoofer is involved, also check its polarity switch — the main speakers can be fine while the sub is inverted.

Should I use 100 Hz or 1 kHz for this test?

100 Hz shows cancellation clearly through missing bass. 1 kHz makes the hollow, unfocused character easier to notice for some listeners. Try both; trust the clearer difference.

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