Subwoofer Test
Check how deep your subwoofer really plays. Six kick drums step down from 70 to 20 Hz — each should sound deeper than the last, never louder. Then a single-channel sweep from 200 to 40 Hz finds the frequency your crossover should sit below.
Six identical kicks, stepping down from 70 to 20 Hz. Depth should change — loudness should not.
Play the kicks, then mark the deepest one you could clearly hear or feel.
A tone glides from 200 down to 40 Hz through one channel only. Press the button the moment it no longer sounds like it comes from that side.
Run the sweep on each side and note where the tone drifts to the centre.
Start around 50% and turn up slowly — deep kicks carry far more energy than music at the same loudness.
The 20 – 40 Hz kicks need a subwoofer or good over-ear headphones — laptop and phone speakers physically cannot reproduce them.
Every kick is generated at the same level. If the deeper ones play louder, the sub’s gain is set too hot.
At 20 – 30 Hz a good system makes pressure you feel in your chest more than a pitch you hear. Vibration counts as a pass.
Keep the crossover below your localization frequency — usually 80 Hz — so bass never points at the sub’s corner.
A subwoofer has one job: reach the frequencies your main speakers cannot. It is routinely given another — making everything louder — and that is the misconfiguration this test exposes. All six kicks are generated at the same level; only the fundamental drops, from 70 Hz down to 20 Hz, so each one should reach deeper without getting louder. If they do get louder the moment the sub joins in, its gain or crossover is boosting bass the mains already cover. If the deepest kicks fade to a faint click, that is the true floor of your setup.
Every kick is synthesized locally by the Web Audio API, the way an analog drum machine does it: a pure sine wave whose pitch drops quickly onto the target frequency while the level decays — the 808 recipe. That purity matters, because a 20 Hz kick contains essentially nothing above 20 Hz; gear that cannot reach it gives you near-silence rather than a reassuring thump of harmonics. The sweep exploits a different quirk: your brain locates low tones by timing differences between your ears, and below roughly 80 Hz the wavelength is so long — several metres — that both ears receive the same signal.
Reading the kick drum test
| Deepest kick heard | What it means |
|---|---|
| 20 Hz | Full sub-bass reach — the bottom of human hearing. True subwoofer or reference-grade headphones. |
| 30 Hz | Excellent extension. Cinema rumble and 808 drops arrive intact. |
| 40 Hz | Solid reach — a good subwoofer or capable over-ears. Most music is fully covered. |
| 50 – 60 Hz | Upper bass only. Bookshelf speakers or a small sub: punch, but no weight. |
| 70 Hz | No subwoofer reach at all. Check the sub’s power, cable, and crossover before blaming the driver. |
Bass localization and your crossover
The frequency the sweep gives you is your critical localization frequency. Below it bass has no direction — which is exactly why one subwoofer can serve a stereo or surround system without collapsing the image. Set the subwoofer crossover under that number; for most rooms and ears, 80 Hz is the safe classic. Set it higher and upper-bass notes become locatable at the subwoofer’s physical position — a bass guitar suddenly playing from the corner of the room. Run the sweep with the subwoofer bypassed if you can: if the tone fades out before it drifts to the centre, your mains ran out of low end before your hearing ran out of direction.