Signs of a Blown Subwoofer: How to Tell and What to Do

Ryan Smith

Something sounds wrong with your sub. Before you assume it’s dead, run through this. I’ve diagnosed hundreds of subwoofer issues over the years and most of them weren’t what the owner thought they were.

The Most Common Symptoms

Distorted or Scratchy Bass — Usually the Driver

If your sub plays bass but it sounds harsh, gritty, or scratchy at volumes where it shouldn’t be distorting, the voice coil is likely damaged. The voice coil sits inside a magnetic gap. When it gets damaged from overheating or overpowering, it starts scraping against the magnet, which produces that characteristic scratching sound. Turn it down and the scratching goes away — turn it up and it comes back. That’s the pattern.

Complete Silence — Could Be Either

No sound at all could mean the voice coil is completely burned out, the driver suspension is broken, or — most likely — there’s a connection or settings issue. Before assuming hardware failure, work through the troubleshooting steps below. Most silent subs I’ve investigated weren’t broken at all.

Sub Goes Into Protection Mode — Usually the Amp

If the power light blinks, changes color, or the sub turns on briefly then shuts off, it’s entering protection mode. This usually means overheating. Let it cool for 30 minutes, check that nothing is blocking airflow around the cabinet, and try again. If it keeps shutting down, there’s either an amplifier fault or the driver is creating a load issue.

Hum Without Bass — Usually the Amp or Connections

A constant hum (50 or 60Hz depending on your country) with no actual bass output is almost always an electrical issue — a ground loop from different outlets, or a failed capacitor in the amplifier. Try plugging everything into the same power strip and see if it clears. A ground loop isolator on the RCA cable (available on Amazon) fixes it 80% of the time.

Quick Diagnostic Tests

The Phone Test

Connect a phone or tablet directly to the sub’s line input using a 3.5mm-to-RCA cable. Play bass-heavy music. If it works: the sub hardware is fine and the problem is your receiver settings, cables, or connections. If it doesn’t work: it’s a hardware issue.

The Hand Test

Hold your hand close to the driver while playing bass. You should feel air movement. No movement means either no signal is reaching the driver, or the driver itself isn’t moving.

The Cone Test

With the sub powered off and unplugged, gently press the center of the cone with two fingers — evenly, not at an angle. It should compress smoothly and spring back evenly. Grinding, scraping, or uneven resistance means the voice coil is damaged or the motor is misaligned.

The Battery Test

Disconnect the speaker leads from the amp. Briefly touch a 9V battery’s terminals to the speaker input terminals. A healthy driver will make a thump and the cone will move forward. No movement means an open circuit — the voice coil has failed.

Before You Assume It’s Blown — Check These First

• Is the sub powered on and the indicator light illuminated?
• Is the RCA cable properly seated at both ends? Try a different cable.
• Is the subwoofer enabled in your receiver’s settings?
• Is the gain knob at minimum? Slowly increase it.
• Are your main speakers set to “Large” in the receiver? (That prevents bass going to the sub.)

I can’t count how many “broken” subs I’ve encountered that had the receiver’s speakers set to “Large.” That one setting silences the sub completely and has nothing to do with hardware failure.

Can You Fix It?

Driver damage: reconing is possible but rarely cost-effective on budget subs. On anything under $300, replacement makes more sense. On a higher-end sub, contact the manufacturer first — warranty and support vary significantly.

Amplifier failure: sometimes repairable by a technician, depending on the fault and parts availability. For SVS owners specifically, their support team is worth calling — they’re genuinely good at this.

If You’re Replacing It

The Klipsch R-120SW is where I’d start if I was replacing a budget or mid-range sub that died. Better than most of what people replace, and the improvement is immediately obvious. If music accuracy matters, the SVS SB-1000 Pro with its 5-year warranty means you won’t be having this conversation again for a long time.