How to check a speaker for damage
This page opens on the Sweep tab, set to the left channel only and a slow 30-second sweep, so you hear one speaker at a time.
- Turn the volume down on your device and on the amplifier. A damaged speaker can get worse if you push it, and a buzz is easier to hear at a moderate level.
- Press Start sweep. A pure tone glides from 20 Hz to 20 kHz through the left speaker only. Press Mark this frequency whenever you hear a buzz, rattle or crackle, or when the tone drops out or jumps in level.
- Set Channel to Right only and sweep again. A pair of identical speakers should behave the same; a buzz or a gap on one side only points at that speaker.
- Open the Left / Right tab, where pink noise is already selected, and press Alternate L/R. The two sides should sound identical. A speaker with a failed tweeter sounds dull and muffled next to its partner, and one with a damaged woofer sounds thin.
- On the Bass tab, play the steady tones from 120 Hz downwards. Buzzing or a flapping noise on low tones at a modest volume is the classic sign of a torn cone or surround, or a voice coil rubbing inside its gap.
What the results mean
- A buzz at the same frequency on both speakers. Probably not the speakers: something in the room resonates at that pitch, such as a shelf, a window or a picture frame, or the volume is high enough to make the amplifier distort. Touch nearby objects while the tone plays to find it.
- A buzz on one speaker only. Check that speaker’s grille, cabinet screws and anything resting on it first, then suspect the driver.
- The tone vanishes above a few kilohertz on one side only. The tweeter, or the crossover that feeds it, has likely failed. With the volume turned down, put your ear close to the tweeter while the sweep passes through the treble.
- Crackling that comes and goes when you move a cable. A loose connection, not a blown speaker. Re-seat the wires at both ends.
- Distortion at every frequency, even when quiet. Swap the left and right speaker cables at the amplifier, so each speaker keeps its own cable but gets the other amplifier channel. If the distortion stays with the same speaker, it’s that speaker or its cable; if it moves to the other speaker, it’s the amplifier channel or the source.
What speaker makers say to listen for
Rockford Fosgate lists scratching or buzzing as the most common sounds of a blown car speaker, says poor-quality bass can mean a damaged surround (the flexible ring around the cone), and notes that a completely blown speaker plays nothing at all. Celestion, which makes guitar and PA speakers, adds that small tears in the cone often cause buzzing. The sweep finds both: a buzz shows up as the sweep passes the frequencies that make the damaged part vibrate, and a dead driver leaves a gap.
Checking a speaker with a multimeter
A silent speaker can be a dead driver, a broken cable or a dead amplifier channel; a multimeter tells the first apart. Switch off and disconnect the speaker, set the meter to resistance (Ω) and touch the probes to the speaker’s terminals.
- Close to, but below, the rated impedance. The coil is intact. Eminence gives 5.1 to 8 ohms as the normal range for an 8-ohm speaker and 2.1 to 4 ohms for a 4-ohm one, because the meter reads the coil’s DC resistance, which is lower than the impedance printed on the speaker.
- OL, or a very high reading. Crutchfield explains that high resistance means a connection somewhere in the speaker has broken, and that a very low reading means a short. Either way the speaker needs repair or replacement.
A normal reading doesn’t prove the speaker is healthy. A torn surround or a coil that rubs still measures fine, and those are exactly what the sweep and bass tones reveal.
Laptop, phone and car speakers
Silence at the bottom of the sweep doesn’t mean a small built-in speaker is blown: it simply can’t play that low. The laptop speaker test has bass tones in the range those speakers actually reach. In a car, use the head unit’s balance and fader to single out each speaker: with the fader fully to the front and the channel set to Left only, the sweep plays through the front left speaker alone.
If both speakers sound healthy but the sound is hollow and lacks bass, they may simply be wired out of phase: the speaker polarity test checks that in a minute. The full speaker test opens on the plain left and right check.