Subwoofer Making Humming Noise | Unbiased Advice & Insights

Published July 29, 2026 · Reviewed by the Unbiased Advice & Insights editorial team · How we research and score

Quick answer

Subwoofer hum is usually caused by a ground loop. Try a ground loop isolator or plug all audio equipment into the same power strip.

Why Your Subwoofer Is Humming

A humming subwoofer is a common annoyance. The hum is typically a low-frequency 60 Hz (or 50 Hz in some regions) tone caused by electrical interference. The three main culprits are ground loops, cable problems, and electromagnetic interference.

Ground loops occur when there is more than one path to ground between components, creating a loop that acts like an antenna. This picks up AC hum. For example, if your subwoofer is plugged into one outlet and your receiver into another, the ground potential difference between the two outlets can cause a hum. Faulty or poorly shielded cables can also introduce noise. A damaged RCA cable with broken shielding can let in radio frequency interference from nearby devices. Interference from nearby electronics (like Wi-Fi routers, fluorescent lights, or power supplies) can induce a hum in the subwoofer's input or amplifier. Even a dimmer switch in the same room can radiate noise that gets picked up by the subwoofer's circuitry. The hum may vary in intensity depending on what other devices are turned on or off.

How to Fix Subwoofer Hum: Step-by-Step Troubleshooting

Follow these steps in order. Test after each step to see if the hum is gone. It is important to test with no audio playing and the subwoofer volume set to a normal listening level.

Check all cable connections. Ensure RCA cables are fully inserted and not loose. Try wiggling the cables while the subwoofer is on to see if the hum changes. Replace any damaged cables. Sometimes a cable that looks fine can have an internal break; swapping with a known good cable is a quick test.
Disconnect the input signal. Unplug the RCA or LFE cable from the subwoofer. If the hum stops, the issue is in the signal chain (receiver, cables). If the hum continues, it's likely a power or ground issue. This is the most important diagnostic step.
Plug everything into the same power strip. Connect your subwoofer, receiver, and other audio gear to a single power strip. This reduces the chance of a ground loop by ensuring all components share the same ground reference. Use a high-quality power strip with surge protection.
Use a ground loop isolator. Insert a ground loop isolator (a small inline device) between the subwoofer cable and the subwoofer input. This breaks the ground loop without affecting audio quality significantly. Isolators are available for around $20 and are easy to install.
Try a different electrical outlet. Sometimes a particular outlet has poor grounding. Plug the subwoofer into a different outlet (preferably on the same circuit as your other gear). If you have a multimeter, you can check the outlet's wiring: the hot slot should be 120V relative to neutral, and neutral should be near 0V relative to ground.
Move the subwoofer away from interference sources. Keep the subwoofer at least a few feet away from Wi-Fi routers, power supplies, dimmer switches, and fluorescent lights. These can radiate electromagnetic interference. Also, avoid running audio cables parallel to power cords; cross them at 90-degree angles if they must be near each other.
Check the subwoofer's ground lift switch (if available). Some subwoofers have a ground lift switch that disconnects the audio ground from the power ground. Flipping it may stop the hum. This switch is often found on the back panel near the power cord.
Use a cheater plug (with caution). A three-to-two prong adapter lifts the ground pin. This can stop hum but removes a safety feature. Only use temporarily to test, and never defeat the ground permanently. If the hum stops with the cheater plug, the problem is definitely a ground loop, and you should use a ground loop isolator instead.

When to Replace Your Subwoofer

If you have tried all the steps above and the hum persists, the subwoofer's internal amplifier may be faulty. Capacitors can degrade over time, causing hum. Also, a damaged voice coil or loose transformer can produce a mechanical hum. In these cases, repair might cost more than a new subwoofer. Consider replacing the unit if it is older than 5-7 years or if the hum is loud and constant. Check the current price on Amazon for reliable models like the SVS SB-1000 Pro or Klipsch R-120SW. Before buying a new subwoofer, you can also try swapping the subwoofer with a friend's to confirm that the problem follows the unit, not your setup.

Understanding Ground Loops in Detail

A ground loop is created when audio components are connected to different electrical outlets that have slightly different ground potentials. This voltage difference (often just a few millivolts) causes current to flow through the audio cable's shield, which then gets amplified by the subwoofer's amplifier and heard as a hum. The hum is typically at the power line frequency (60 Hz in North America, 50 Hz in Europe) and may include harmonics (120 Hz, 180 Hz, etc.). Ground loops are more common in home theater systems with multiple components plugged into different outlets. To prevent ground loops, use a single power strip for all audio equipment, or install a dedicated circuit for your home theater. If you have cable TV or satellite, the ground loop can also involve the cable TV ground; a ground loop isolator on the coaxial cable may help.

More guides

See our full buying guides hub and our research and scoring methodology. We compared specifications and verified owner feedback; we did not physically test every product.

Common questions

Can a subwoofer hum damage the speaker?

A low-level hum usually won't damage the subwoofer, but it can be annoying. However, if the hum is accompanied by distortion or excessive heat, it may indicate a more serious issue that could harm the amplifier or driver. In such cases, unplug the subwoofer and consult a professional. For example, if the hum becomes louder over time or you notice the subwoofer cabinet vibrating excessively, internal components may be failing. A humming sound that changes pitch with volume adjustments might point to a failing capacitor in the power supply. If you smell burning or see smoke, immediately disconnect the subwoofer and do not use it until it has been inspected by a qualified technician.

Will a power conditioner fix subwoofer hum?

A power conditioner can help if the hum is caused by dirty power or voltage fluctuations. However, it won't fix ground loop hum. For ground loops, a ground loop isolator or lifting the ground (with caution) is more effective. Power conditioners typically include surge protection and noise filtering for radio frequency interference (RFI) and electromagnetic interference (EMI). If your home has old wiring or you live near a power substation, a power conditioner may reduce background hum. But if the hum is a steady 60 Hz tone that stops when you disconnect the input cable, the problem is almost certainly a ground loop, not dirty power. In that case, a dedicated ground loop isolator (costing around $20 to $40) is the right solution.

Why does my subwoofer hum when nothing is playing?

This is typical of ground loop hum or interference. The subwoofer's amplifier picks up a 60 Hz (or 50 Hz) AC signal from the electrical system. Disconnecting the input cables can help isolate the cause. If the hum stops, the issue is in the signal path; if it continues, it's likely a power or grounding issue. For instance, if you unplug the RCA cable from the subwoofer and the hum disappears, the problem is upstream: your receiver, the cable itself, or a ground loop between the receiver and subwoofer. If the hum remains even with no input connected, the subwoofer's internal amplifier may be faulty, or there could be interference from nearby electronics like a refrigerator compressor or a dimmer switch. Try moving the subwoofer to a different location or plugging it into a different outlet to rule out external interference.

Can a subwoofer cable cause humming?

Yes, a damaged or poorly shielded subwoofer cable can introduce hum. If the cable's shielding is broken or the connectors are loose, it can act as an antenna and pick up electromagnetic interference. Try replacing the cable with a high-quality shielded RCA cable. Even a cheap cable with good shielding can make a difference. Also, ensure the cable is not running parallel to power cords, as that can induce hum. If you have a long cable run (over 25 feet), consider using a balanced connection if your equipment supports it, or use a line driver to boost the signal.

What is the difference between a ground loop isolator and a power conditioner?

A ground loop isolator breaks the electrical continuity of the ground path between components, stopping the loop that causes hum. It is a small inline device that connects between the subwoofer and its input cable. A power conditioner filters the AC power line to remove noise and voltage spikes, but it does not break ground loops. If your hum is caused by a ground loop, a power conditioner will not help. If your hum is caused by dirty power or interference from other appliances, a power conditioner may reduce it. For best results, identify the type of hum first by disconnecting the input cable.