How to Fix or Eliminate Subwoofer Hum

You cabled up a new speaker to your sound system, positioned the subwoofer for optimal performance, and tweaked the audio equalizer so that everything sounds perfect to your ears. You sit down to relax and listen but notice something is off. A conspicuous, persistent hum emanates from the subwoofer, and it shows no signs of going away. In this article, we show you how to fix it.

Causes of Subwoofer Hum

Subwoofer hum or buzz is a low-level noise that can be present whenever a passive or powered subwoofer is turned on, whether or not it is playing. This 60-hertz hum is a result of being plugged into an AC wall outlet.

Sometimes the hum is noticeable; sometimes, it takes some focused listening to notice. Either way, you can correct the situation without resorting to filtering out the noise, which also strips out audio signals. Usually, all it takes is a change in the way the subwoofer connects to power.

How to Fix Subwoofer Hum

You can take several approaches to get rid of the annoying hum. If the first suggestion doesn't work, try one of the others.

1. Change the polarity of the subwoofer's connection. This is probably the most straightforward fix to try because all it involves is reversing the power plug's orientation. Sometimes, one prong is wider than the other, which may prevent the reversal. In such situations, use an AC ground adapter to reverse the polarity. Most of these adapters have uniform-sized prongs and are available at local home improvement stores.

2. Reverse other plugs. When components share the same source, such as a power strip or surge protector, the culprit may not be the subwoofer. It could be some other two-prong AC plug. One by one, reverse the orientation of the other plugs to see if it makes a difference.

3. Separate the cables. When you cluster power or audio cables in bundles, signals bleed over and create noise because of their proximity. Space cables apart so the electrical fields created by moving current don't interfere with each other. If you can't separate them a sufficient distance, upgrade the audio cables to ones with more effective shielding.

4. Switch outlets. Sometimes the subwoofer hum is caused by a ground loop, which happens when it's fighting a second device for possession of the ground. If you have another three-prong piece of equipment sharing the same wall outlet, power strip, or surge protector as the subwoofer, move the subwoofer to another AC circuit in the room. It may be necessary to use an extension cord to reach a wall outlet that is separate from the rest of the stereo system.

5. Use an audio isolation transformer. If the previous grounding techniques haven't worked, consider purchasing and installing an audio isolation transformer. Many are designed for powered subwoofers and connect in line with the cables. They instantly resolve ground loops.