Speaker Test — Balance & Polarity

Online speaker test with left-right pink noise, 1 kHz tone, balance walk and polarity check with mono sum. Find wiring faults fast. Free in your browser.

Your result

Polarity check: waiting for a verdict

To check polarity: choose Both, set polarity to Inverted, and turn Mono-sum On — the result appears here.

What did you hear?

Out-of-polarity found

Your two speakers are working against each other: one pushes while the other pulls. That thins the bass and blurs the centre image — it is a wiring problem, not a speaker or software problem.

Fix it now

  1. Check both ends of the speaker cable: red to red (+), black to black (−), at the amplifier and at the speaker.
  2. If one speaker was rewired recently, that is almost always the culprit — put that one back the way it was.
  3. Re-run the check with Mono-sum on: reinforcement means the pair is back in step.

If that didn't fix it. If the wiring is correct at both ends, check for a polarity or phase setting in your amplifier, mixer, or operating-system sound panel.

In phase — wiring is correct

Both speakers push and pull together, and the pair sums correctly in mono. Your routing and relative polarity are fine.

Fix it now

  1. Nothing to fix here. If the centre image still feels off, check that both speakers sit the same distance from your listening position.

If that didn't fix it. If mixes still don't translate when the wiring is right, pick "Checks pass, but mixes don't translate" above.

One side louder than the other

A level mismatch pulls the phantom centre toward the louder speaker. Even 1–2 dB is audible; this is about gain, placement, or the room — not polarity.

Fix it now

  1. Set both channels to the same gain: amplifier or powered-speaker trims first, then the operating-system balance slider.
  2. Swap the speakers (left ↔ right) and re-check: if the louder side follows the speaker, it is the speaker or its room corner; if it follows the channel, it is the amplifier or cable.
  3. Move both speakers out of corners and away from side walls; a corner adds several dB of bass to that side.

If that didn't fix it. A calibrated measurement microphone is the only way to separate a speaker problem from a room problem at your listening position.

Thin or hollow sound

A hollow midrange with weak bass usually points at phase problems: a reversed polarity somewhere in the chain, or a large path difference between the speakers.

Fix it now

  1. Run the polarity check above — a single reversed speaker causes exactly this.
  2. Measure the distance from each speaker to your ears and keep the difference under a few centimetres.
  3. Check for any '3D', 'spatial', or 'mono' mode in your operating system or amplifier and switch it off.

If that didn't fix it. The Audio Wizard's stereo and phase tree walks through the same checks in order.

The setup is fine, but mixes don't translate

Your wiring, balance and polarity all check out. If mixes still sound different on other systems, the usual cause is the room and speaker response colouring what you hear — that is a calibration problem.

Fix it now

  1. Treat the biggest reflections first: move speakers away from walls and break up the first reflection points.
  2. Measure your room's response at the listening position before buying anything — guessing wastes money.
  3. Apply correction for the response errors you measured, not for what marketing pages claim.

If that didn't fix it. Room treatment fixes decay; response correction fixes tone. Most untreated rooms need a bit of both.

Going further

Calibration software measures your speakers and room, then applies a correction profile — this is exactly what SoundID Reference is built for. A measurement microphone completes the loop.

See SoundID Reference on Sonarworks

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Open the Audio Wizard

Protect your hearing. Start at a low volume. Never raise the volume to make a tone audible. Levels are shown in dBFS, relative to full scale — not SPL.

How it works

Pink noise is generated in an AudioWorklet and a 1 kHz sine is generated with the Web Audio API. Each channel has its own gain path: the right path can be inverted, and a mono sum adds the two paths together. With one channel inverted, the summed output cancels to near silence, which the level meter measures in dBFS. Nothing is uploaded or recorded, and no sound plays until you ask for it.

On this page

    A speaker test checks three things about a stereo system: that each speaker makes sound, that the two are balanced in level, and that they work together in the correct polarity. Pink noise and a 1 kHz tone run through a browser-local Web Audio graph; nothing is uploaded or recorded, and no sound plays until you press Play.

    How to use it

    1. Pick a signal. Press Pink noise for tonal balance or 1 kHz tone for presence and level. Both run at 0.28 gain, so a 1 kHz sine reads about -14 dBFS RMS.
    2. Route it to one side or both. Use the channel buttons Left, Both, and Right. A hard-panned setting feeds one channel only; Both feeds both.
    3. Walk the balance. Press Balance walk: the routing steps Left, then Both, then Right every 2 seconds while the signal keeps playing. Press it again to stop.
    4. Invert one channel. Press “Polarity: Normal (0°)” to switch it to “Polarity: Inverted (180°)”. This flips the sign of the right branch only.
    5. Switch on the mono sum. Press “Mono-sum: Off” to make it “Mono-sum: On”. The mono path adds the left and right branches with a 0.5 gain, so a correlated sum cannot clip.
    6. Read the verdict. With Both selected, polarity inverted, and the mono sum on, the meter falls below -24 dBFS for more than 250 ms and the verdict reports cancellation. Return polarity to normal in mono and the verdict reports reinforcement.

    Left, both and right: what each routing proves

    Left only isolates the left speaker, and Right only isolates the right one. This is the fastest way to find a dead tweeter, a blown woofer, a loose terminal, or a channel that is silent because of a routing mistake. A side that is quieter on pink noise has a real level difference; a side that is quieter on the 1 kHz tone only points at a tweeter or crossover fault.

    Both plays identical correlated content through both speakers. With matched levels and correct polarity the image collapses to a phantom centre midway between them, and the meter reads the louder channel. A 1 to 2 dB mismatch is enough to pull the centre noticeably, which is a smaller error than most listeners expect.

    This page tests the two stereo channels only. A centre channel and an LFE channel need a multichannel source; the surround sound test walks a 5.1 layout whose angles follow the ITU-R BS.775 reference, with front left and right at ±30°.

    Polarity, phase and the mono sum

    Polarity is an instantaneous sign flip: an inverted channel is the mirror image of the original, 180 degrees apart at every frequency. Two identical signals added in phase give twice the amplitude, which is +6 dB; invert one and each positive sample lines up against a negative of equal size, so the sum collapses toward zero. The tool applies a 0.5 gain to the mono sum so the reinforced sum reads near the single-channel level instead of clipping, and the relative change is what matters.

    Polarity is not the same as phase. A speaker wired backwards is polarity-inverted across the whole band; a speaker placed 1 m farther away is delayed by about 2.9 ms, which is a frequency-dependent phase shift. The two speakers then comb-filter, and the first cancellation lands at 343 / (2 × Δd) Hz: 171.5 Hz for a 1 m path difference, 343 Hz for 0.5 m. That is why a polarity error sounds thin and hollow in mono, while a placement error sounds hollow only in a band.

    Check wiring at both ends: red to red and black to black keeps the pair in step, and one end reversed makes that speaker pull while the other pushes. A steady low buzz is a different fault. Mains hum sits at 50 Hz in most of Europe, Asia, Africa, and Australia, and at 60 Hz in North America and parts of Japan, with harmonics at 100/150 Hz or 120/180 Hz.

    Mains hum and frequency reference

    Frequency Wavelength at 343 m/s Period What it exposes
    50 Hz 6.86 m 20.0 ms Mains hum fundamental in 50 Hz regions
    60 Hz 5.72 m 16.7 ms Mains hum fundamental in 60 Hz regions
    100 Hz 3.43 m 10.0 ms Second harmonic of 50 Hz hum; small-speaker roll-off
    120 Hz 2.86 m 8.3 ms Second harmonic of 60 Hz hum
    1 kHz 0.343 m 1.0 ms Reference tone for level and presence
    3 kHz 0.114 m 0.33 ms Ear-canal resonance region; tweeter territory

    Accuracy, limits and troubleshooting

    • Levels are dBFS, not dB SPL. The meter reports digital level on the summed or louder path; it is not a sound level meter.
    • Cancellation is not digital silence. The two branches are not perfectly identical, so the summed path settles below the -24 dBFS threshold rather than at zero. The verdict requires that level to hold for more than 250 ms to avoid reacting to a brief dip.
    • The mono sum uses a 0.5 gain. Do not read a mono measurement as a doubled level. Compare the mono reading with the stereo reading to judge reinforcement or cancellation.
    • Operating-system processing changes the result. Windows audio enhancements, TV and laptop “3D” modes, spatial audio renderers, and mono accessibility settings all alter routing. Disable them before testing.
    • Bluetooth can break relative polarity. A2DP sends both channels in one stream, but some true wireless sets and DSP modes process each side separately, so test wired if a result looks wrong.
    • Room and crosstalk colour the result. A hard-panned Left signal still reaches the right ear through room reflections, so judge polarity with the meter and the mono sum.
    • This page cannot measure frequency response or distortion. It confirms routing, balance, and relative polarity; use a measurement microphone for response curves.
    • Keep levels modest. Pink noise and a 1 kHz tone become uncomfortable quickly, and a 1 kHz tone at high level is hard on tweeters.
    • Subwoofer Test — Discrete low-frequency tones and a 20 to 200 Hz sweep for the bottom end.
    • Headphone Test — Channel isolation, driver matching, and an ITD demo for headphones.
    • Surround Sound Test — Centre and LFE channel walk-throughs for 5.1 and 7.1 layouts.

    Aliases covered on this page: speaker test, speaker polarity test, speaker phase test, speaker balance test, and left right speaker test.

    Frequently asked questions

    How do I test my speakers?

    Play the pink noise or the 1 kHz tone on Left, Both, and Right in turn. Each side should be clearly audible from the matching speaker, and Both should sound centred and even. Pink noise reveals tonal balance; the 1 kHz tone is the reference for level and presence.

    What is a speaker polarity or phase test?

    Polarity describes whether both speakers push and pull in step. When one channel is inverted against the other and the signal is summed to mono, the two copies cancel and the output drops to near silence. This tool plays one channel inverted and lets you switch the mono sum on and off to hear and see the cancellation.

    What is the mono-sum button for?

    A mono sum adds the left and right channels together, the way a mono playback device or a single speaker hears them. With both channels in phase the sum reinforces; with one channel inverted the sum cancels. Watching the level meter drop when you invert polarity in mono is a direct check of relative polarity.

    Why does out-of-phase content cancel?

    When two identical signals are added with one inverted, every positive sample meets a negative one of the same size, so they sum to zero. This is the same physics that makes a speaker wired backwards sound thin and hollow when summed with its twin.

    Which signal should I use for a balance check?

    Pink noise is the classic balance signal, because it carries equal energy per octave and sounds even across the room. The 1 kHz tone is easier to localise by ear and is the standard reference for confirming that a channel produces sound at all.

    Is this safe for my hearing?

    Start at a low volume and never raise the volume to make the signal audible. The tool plays only from a user gesture, provides a persistent Stop and Mute, and reports levels in dBFS, relative to full scale, never in SPL. Pink noise and a 1 kHz tone can both become uncomfortable quickly at high levels.

    How do I test my iPhone speaker online?

    Open this page in Safari, set volume low, then play the left, both and right pink-noise checks in turn. Each side should sound clear from its speaker and the centered signal should sit in the middle. If one side is quiet or distorted at modest volume, clean the grille, then compare on headphones to separate phone faults from track issues.

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