You press play and the subwoofer does almost nothing. Is it blown, muted, miswired, or just sitting in a room null?
I published the full guide on KeyboardTester.click with the live 20 Hz to 200 Hz bass sweep, symptom tables, setup checks, source links, FAQ schema, and localized versions:
Subwoofer Test Online: Is Your Sub Working or Blown?
This Dev.to version keeps the practical diagnostic workflow.
Fast answer
Start the Bass Test at low volume, run the 20-200 Hz sweep, and listen for the pattern.
- Smooth output means the sub is probably receiving signal and working.
- No sound usually points to power, cable, receiver, LFE, crossover, or mute settings first.
- Rattling, scraping, burnt smell, or distortion even at low volume can mean driver, amp, or enclosure damage, so stop testing and inspect safely.
A browser sweep can reveal symptoms. It cannot certify the electrical health of a subwoofer by itself.
Run the test safely
- Turn volume down first. Set system volume and subwoofer gain low, then raise slowly. If you hear scraping, clack, harsh buzzing, or distress, stop.
- Play the 20-200 Hz sweep. Note where sound begins, becomes strongest, disappears, rattles, or changes tone.
- Hold a problem frequency. If the issue appears around 40 Hz or 80 Hz, use hold/step mode to repeat that one tone at low volume.
- Compare routing and placement. Check LFE/sub output, crossover, phase, cable, receiver mode, and room placement before assuming the driver is blown.
What each result usually means
| What you hear | Likely cause | Next check |
|---|---|---|
| Smooth bass from about 30-120 Hz | The subwoofer is receiving signal and reproducing the main bass band | Fine-tune placement, crossover, and gain |
| No sound at any bass frequency | Power, standby, mute, LFE cable, receiver output, PC audio route, or failed amp | Confirm power light, cable, input, receiver sub output, and another source |
| Bass only above 80-120 Hz | Crossover, tiny speaker pretending to be a sub, high-pass filter, or weak low-end capability | Lower crossover carefully and compare with a frequency-response sweep |
| A hole around one narrow frequency | Room cancellation, phase mismatch, or placement null | Move the sub or listening seat, flip phase, and retest |
| Rattle, buzz, or cabinet vibration | Loose grille, loose object, port noise, damaged surround, or driver stress | Remove loose objects and lower volume |
| Scraping or crackling on gentle movement | Possible voice-coil rub, torn spider/surround, or driver damage | Stop the sweep and use service-safe inspection or warranty support |
Settings to check before blaming the driver
Most "dead sub" cases are setup problems before they are hardware failures:
- Power and standby: auto-standby may not wake on quiet signals.
- LFE/sub cable: a loose RCA, wrong output, or wrong input can make the sub appear dead.
- Receiver speaker size: if fronts are set Large and bass management is off, little bass may reach the sub.
- Crossover and gain: too low a crossover or very low gain makes the sweep seem weak.
- Phase and placement: a sub can cancel with front speakers at the listening seat.
- Content mode: Stereo, Pure Direct, night mode, Bluetooth, or TV pass-through can drop LFE.
When to stop testing
Stop if you notice:
- Burnt smell from the cabinet or amp plate.
- Scraping when the cone moves gently.
- Distortion at very low volume.
- Sudden silence after a loud event.
Those signs do not prove the exact failure mode, but they are enough reason to stop feeding sine waves into the subwoofer and move to safe inspection, repair, or warranty support.
Small speakers are different
For headphones, use the sweep to learn where bass rolls off, not to decide whether a subwoofer is blown. For laptop and phone speakers, missing 20-60 Hz is normal physics, not a defect.
Full guide with live tool, tables, sources, and FAQs:
