Why Does My Subwoofer Hum with Nothing Connected?

A subwoofer is in good shape when it produces heavy bass. Moreover, when it produces a humming sound when not connected, you ought to act faster and fix it because something is wrong. In most cases, people troubleshoot by unplugging all the input devices, for instance, an amp or AV receiver, to check if any of them is damaged.

Well, yes, how do you fix the subwoofer after you find that there is a hum even after you remove the input? In this article, we have prepared a step-by-step procedure, which is easy to follow to enable you to troubleshoot the cause of the hum and how to fix it when you have not connected any input to your subwoofer.

We have several potential causes why subwoofers hum, for instance, electrical defects, ground loop sound, and induced noise.

 How to check why the subwoofer hums while it is not connected?

1. Look at the subwoofer’s connectionsubwoofer hums with nothing connected

In a situation where the power plug may be reversed in your electrical socket, it can cause a humming sound in your subwoofer when not connected. Normally prongs are not equal in terms of size. In such a case, look at the sign that maybe one is wider, then plugin accordingly.

However, you can also check if the components share a common source. If you find out it is the case, then the AC plug could cause sound and not your subwoofer.

2. Look whether signals bleed overLook whether signals bleed over

Sometimes signals bleed over and probably cause your subwoofer to hum if the power and audio cables are put together and normally are quite common. The truth is, subwoofers broadcast interference very easily. The only great way to manage your cables well is by using a cable management rack.

In this way, you will prevent the bundling of cables, hence preventing different cables from bleeding signals. A good example is the rack mount horizontal cable is a very nice choice.

3. Consider ground loopConsider ground loop

This is another major cause of humming in the subwoofer, which is not connected. To confirm if this is the cause, you need to look at whether at least two devices are connected to a common ground through different paths. Moreover, it is of importance to know that ground loop is rare if you eliminate all inputs.

Normally, it occurs when the sub is connected to a receiver, causing cable TV connections. An easy fix is grounding the supply of power by connecting one side of your wire to metal chassis, then screwing the subwoofer and the other end to a metallic material and ground. Now check the humming problem again.

4. Look at the internal subwoofer amplifierLook at the internal subwoofer amplifier

Normally, 50 or 60Hz hum is due to power supply leakage into the subwoofer’s amplifier. This may occur due to a problem with the amplifier itself. It is often brought up by power surges that destroy the amplifier. Mostly the cause of these problems is capacitors in the amplifier or power supply which are not damaged.

If you find out it is the issue, replacing the capacitors with better caps will automatically solve the humming problem. However, in any case, the best way is to contact the manufacturer for amplifier replacement. After checking if you find out that a power surge caused it, it is advisable to look for a good surge protector.

5. AC line soundAC line sound

Most of the home devices cause interference on the main AC, more so devices with a motor. On top of that, failing fluorescent fixtures and light dimmers can cause AC choke, which can cause interferences. Jagged lines on your TV is one of the common ways to confirm this effect.

One easy solution to this issue is to switch off all the devices when the subwoofer is blasting. Another method to fix this is to wrap the subwoofer power cable around to create a power choke as you use a ferrite ring.

       Quick ways to fix subwoofer hum which is not connected to any device

Commonly used techniques to fix hum include:       Quick ways to fix subwoofer hum which is not connected to any device

1. Reversal of the power plug orientation

Once you notice one of your prongs is wide, this confirms a problem with your power plug orientation. To fix it, change the connection polarity of the subwoofer.  The power plug’s orientation reversal does it. In some situations, changing the polarity of your connections may not end the problem, hence consider a reversal of other plugs.

2. Separate the cables

During troubleshooting, if you realize that audio and power cables are clustered, this could have been caused by a subwoofer hum. The proximity can make the signals mix up hence causing the humming. In this case, you should increase the space in which the fields that the currents move don’t interfere with each other hence fixing the noise.

Because of limited space, you may not stop the interference of the electric fields; upgrade the audio cables.

3. Switch outlets

If you find out that a ground loop is causing a subwoofer hum, turn off the outlet you are using. You can take your subwoofer to another AC in your room. If you don’t reach an extension wall, then separate it with your sound system, make use of the extension cord. Hence you will have fixed the ground loop.

4. Replace the amplifier

After you have exhausted the option above and still the humming sound is there, then you need to replace your amplifier altogether.

You might be interested to read also our another article of: Why Does My Subwoofer Hum When the Receiver Is Off?


A persistent hum in your subwoofer can make you uncomfortable when no device is connected to it. Sometimes you can disconnect all devices then leave speaker cable, loudspeakers, and AC plug, but the 60-hertz hum is still there.in most cases, plugging your unit into the AC outlet can be the only direct solution to this low-level sound.

By following the above procedure, you should be able to troubleshoot your subwoofer and find out why it hums when not connected to any device. In case of any complicated challenge, it would be of help if you consult an expert to guide.

For more about fixing subwoofer hum, you should watch this video bel0w. enjoy!

Leave a Comment