This is likely a ground loop causing current to flow through your subwoofer audio cable because of voltage differences between the subwoofer electrical ground and your equipment ground.
- Disconnect the cable to the subwoofer to see if the hum disappears. If you remove the cable and the hum goes away you have a ground loop problem. If the hum persists without the audio cable your subwoofer may be defective or the subwoofer volume may be too high.
- If you have a ground loop locate the source by disconnecting equipment with grounds connected to your receiver with either a video or audio cable until the hum goes away. This excludes optical audio connections. Common causes are cable TV or satellite TV connections to the cable box or TV, different ground potentials caused by equipment plugged into different outlets, different electrical phase on devices and poor equipment design.
- If that does not locate the source try replacing the cable running to the subwoofer. Sometimes a defective cable can cause this.
- If the source is the cable TV either correct the grounding error or use a Jenson isolator. You can also consider using an optical audio connection from the cable box to stop this, but if you are switching video through the receiver this is not likely to work.
- If the source is the satellite TV you must fix the grounding problem on your satellite system or use an optical audio connection and remove video switching from the receiver.
- If the source is differences in electrical grounds you must either have an electrician fix the electrical ground problem in your home or use products like these.
- If the source is the receiver or subwoofer itself it may be necessary to send it back for repair or replace it. Only resort to this after exhausting all other options.
More information on this topic can be found in this great article by Bill Whitlock.
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Hi VEry nice posts i’sure i’sts nice
Super-Duper blog! I am loving it!! Will be back later to read some more. I am taking your feeds also
very nice posting… i have a set home theater at home and i use subwoofer however
Awsome site! I am loving it!! Will be back later to read some more. I am taking your feeds also.
Just want to thank you for the information. It really helped a lot!
I´ve just solved 99% of my subwoofer hum and wanted to leave my comments.
Problem appeared when I connected a Denon ST501 receiver with my active sub-woofer (DIY project with 12V/30A switching PS + 250W Class D amplifier).
– at first I realized the house grounding was not “grounding” properly my power supply so I made an additional one at the garden (3 x 1/2″ cooper sticks/ 6 feet each).
– after this I also checked the Denon chassis had a voltage of 40-50Vac when measured to the new ground of my PS. Problem is that Denon has only 2 prong!!
– So I just got one of the chassis screws and connected it to the ground screw of my PS.
ps: even knowing that many comments tells you to do not ground the Denon chassis. That was the most effective measure to reduce the hum.
Another tip: if you want to be sure you have a ground loop, replace your audio source by your cell phone audio. Since it is not connected to your house AC net you should stop the hum.
Very informative, thank you, although i’ve never personally had this issue, ill bookmark it just in case.
I started getting the hum issue when connecting a second sub to the AV receiver. Using your steps above, I was able to pinpoint the issue to the shitty subwoofer cable from Best Buy. Replaced it with the one from Mediabridge and the hum went away. Much much thanks.
pick up powered subwoofer lately (velodyne impact mini). It created humm sound each time I turned off my Reciever. After I read from this article. yes it was the Insignia subwoofer rca cable from Best Buy causing the grounded noise . I bought amazon basic Y-splitter rca cable,it work just fine. Thanks for the info.
In my case I have subwoofer hum exactly when I turn on a ceiling LED light in the room. The hum goes off when I switch the light off….
Any ideas?
Hi, I am Steven Paul Your article “Subwoofer Hum” is very helpful for me. After reading your article I got a lot of knowledge from your article. I have some knowledge about Subwoofer but after reading your article I think; I have to gain more knowledge about this topic. Thanks!
Like me, you may be using the wrong type of wiring. If it’s not 75 ohm coaxial cable, that could be the problem. 75 ohm coax is the wire that’s used for cable TV. I read all the forums and tried all of the other solutions. I isolated wires, removed adjacent power sources, bought grounded isolation connectors and even bought a new subwoofer, etc. Nothing worked!
I am running a preamp signal from the A/V closet I built to the subwoofer, a distance of about 50 feet. You may need special adapter(s) to connect the 75 ohm wire to the preamp input on your subwoofer. However, speaker wire will not work. If you are a DIY low-voltage full-house home wiring person like me, the wire is probably the cause. Hopefully you are like me and ran a cable TV wire in your wire bundle to the subwoofer.