How to Troubleshoot an Amp Hum With No Input – Easy Ways

When your subwoofer is in good condition, then you expect it to deliver excellently. Sometimes, however, your subwoofer ends up producing humming sounds; hence you need to fix the problem. Such noises are irritative. They interfere with one’s keenness when listening to audios.

Someone will opt to unplug all connected input devices to get rid of the problem, which is good. However, the humming might persist even after unplugging these devices. This is a common problem and can be fixed. This article will guide you on the possible causes of the problems and how to eliminate them.

Troubleshooting amp hum with no inputamp hum with no input

Your subwoofer may produce pulsating sounds like a heartbeat. It may also make cracking noises due to various problems. To detect the key cause of the humming problem, you need to do the following;

  • Do a check-up on your subwoofer connection.

The way the power plug is oriented might result in a hum on your subwoofer. For instance, a reversed plug in your socket will cause hums. Ensure that you know the size of the plugging points and plug each device according to their sizes. Components sharing the same power source can cause noise.

  • Check on signals interference.

Often, signals bleed over, causing hums in your subwoofer. It happens especially when the audio cables are bundled with power cables. Bunching these cables together is a common thing and results in interferences. There is thus a need to manage the way your cables are fixed.

 One can use a cable management rack, thus preventing the signal-bleeding of the cables.

  • Check the internal amplifier of your subwoofer.

Humming might result due to power supply leakages into the subwoofer’s amplifier. Loose connections and power surges often cause leakages, damaging the amplifier. Ensure that amplifier capacitors remain in good conditions; otherwise, these problems will occur.

Damaged capacitors should be replaced to get rid of the problem. Your subwoofer should be protected against power surges.  Getting an appropriate surge protector will always ensure that the problem is fixed. Acquiring the surge protector will protect not only your protector but also all other home entertainment devices.

Replacement of the amplifier can as well help. Ensure that you acquire the amplifier from the manufacturer. In this way, it will be cost-effective. The person will help you in fixing the replacement, which maybe you could not.

  • Ground loop consideration

Subwoofer hum may result due to the presence of a ground loop. Two or more devices connected in a common AC but different tracks create a loop. Disconnecting all input devices, however, from the AC will help fix this problem. It’s rare though the ground loop to occur when inputs are disconnected.

When your subwoofer is, however, connected to a receiver, a ground loop might occur. This causes interference with TV cable connection. 

  • AC line hum

Motored appliances such as blenders, hairdryers, and coffee grinders cause interferences AC mains resulting in a hum. In TVs, this problem is evident in the form of uneven lines displayed on the screen. However, this problem can always be rectified.

When your subwoofer is in use, it is important to disconnect or turn off other devices. Turning off these devices helps in fixing the problem. One can also apply a ferrite ring to the subwoofer’s power cable.

Ways to fix amp hum with no inputWays to fix amp hum with no input

Elimination of amp hums requires one to understand the cause of the problem to fix it perfectly. The problems can be easily fixed when the exact cause is identified. One can try several fixing options when they do not exactly know the cause.

The various ways to get rid of the problems include;

a. Try switching the outlets

Switching the outlets in use will help solve the ground loop problem. If your room has a different AC line, you can try moving your subwoofer to the other circuit. You can op use an extension cable in case you are unable to reach the AC line. The ground loop is this fixed.

If this tip does not work, one can install an audio isolation transformer, which then solves the hum. A different way to solve this problem is by removing all inputs from your sound system.

b. Separate the cables.

When your power cables are bundled with the audio cables, it may result in an amplifier hum. The cable’s closeness can lead to the signals mixing up hence causing hums. It is thus vital to increase the line spaces. It ensures that created current fields do not get any interference.

Ensure that you consider the cables you acquire also. It will be difficult for you to create an extra amp space. Thus, acquire cables that are highly shielded, and in this way, the humming problem will be fixed.

c. Reverse the power plug orientation

A wider prong is a clear confirmation that the orientation of your power plug has a problem. However, it can be fixed. Reverse the orientation of the plug by changing the subwoofer’s polarity. Use a uniform-sized prongs AC adapter, which is available locally in most cases.

In your attempts to fix the hum, the first trial might not work. Thus, it’s logical to try reversing other plugs. In most circumstances, your system components are fixed in the same power supply leading to the humming problem. To solve this, ensure you reverse each plug’s orientation.

d. Fixing or replacing the amplifier

After several fixing trials, you may end up not solving the humming problem. For this case, the amplifier might be the problem. If there might be damaged components, then you can try to fix them. If the fixing does not work, then you can replace the entire amplifier.


Humming problems are common in any sound system. The problem results regardless of any input device connection. It may be connected or not. One can disconnect all input devices from the power source but still, hear hums from the subwoofer or the amplifier.

Humming problems in your amplifier with no input can be eliminated by the above-discussed tips. There might be more ways to fix these problems, thus being easier to get rid of the humming. The cause of the hums might be more than one. Ensure that you thoroughly inspect the cause of the problem and apply the tips to fix it.  

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