Reconnect your subwoofer's coaxial connection from the subwoofer input to the subwoofer output of your receiver, then unplug the cable-TV feed (or satellite feed) from your outboard set-top cable box or satellite tuner. Make careful to unplug the connection before installing any splitters. Check to check whether the hum or buzz from your subwoofer has stopped. If it hasn't, then reconnect the coaxial connection again.
Subwoofer hum or buzz is a low-level noise that may be heard whenever a passive or powered subwoofer is turned on, regardless of whether it is playing or not. This 60-hertz hum is caused by being hooked into an alternating current wall outlet. Typically, all that is required is a tweak in the way the subwoofer connects to electricity. A simple fix for this problem is to connect the black and red wires of the subwoofer's power cord to different sides of the outlet; then there will be no voltage between the wires and thus no hum.
The term "buzz" is also used to describe similar noises generated by other equipment with electric motors, such as lawnmowers and snowblowers. These machines tend to make more mechanical noise than the hum produced by a subwoofer, but they can be difficult to distinguish from one another when played at high volumes.
Hum occurs because electric motors are constructed based on electromagnetism principles, which means that they generate electrical energy whenever they are turning, even if they are not receiving any power from a source. This is exactly what happens with a subwoofer when it is plugged in but not playing anything. The motor inside it is still spinning at full speed, generating electromagnetic waves that set off vibrations in everything around it.
What is the source of the humming noise coming from my subwoofer? The voltage differential between the electrical ground of a subwoofer and the equipment ground might cause it to hum. This is caused by the uneven current flow in your audio wire. A hum might also be caused by turning up the volume too much. If there is any metal near where you are connecting your subwoofer's wires to your amp, it may create an RF loop that can interfere with the signal being sent by your amplifier.
To fix this problem, first make sure that all of the metal parts of your subwoofer are connected to the same ground point. Then check to see if there are any metal objects between your subwoofer and your amplifier. If so, move them away from each other as much as possible while still keeping the signals flowing properly.
Also, try not to connect more than one cable at a time to your amp's power socket. This will help reduce the chances of interference caused by unequal currents. If you still have problems after trying these steps, then you should consider getting a new subwoofer or amplifier.
How to Remove Subwoofer Hum
As you switch off each item, pay close attention to the amp to check whether the hum goes away. If you can still hear the hum, restart the equipment since it wasn't harming your amplifier. You won't be able to totally eliminate the interference, but it will be less obvious. In fact, many people will never notice that their amp produces noise even when they aren't playing anything.
The best way to get rid of the hum from your amp is by replacing some of the components with new ones. This will eliminate any internal sources generating noise which could be causing your problem. Of course, this isn't always possible or practical, in which case you need to find the source of interference and fix it. Some common causes of audio feedback include:
A loose connection. Make sure all cables are tight and there are no broken wires anywhere in the system.
An open circuit. Check all power supplies are plugged in and working properly.
A short circuit. This can happen if a conductor such as a wire gets pinched between two metal objects such as a chassis fork or another component. It's easy to miss when checking your equipment, so make sure you don't have any open circuits or short circuits anywhere in your system.
Audio gear is complex machinery, so it's not unusual for problems to arise from time to time.