Axiom Home Page Forums General Discussion Home Theater Can't kill the humming in my sub..help

Mongo, a puzzling point here is that two of your observations appear to be directly contradictory: in 2)when you used the cheater plug, it should have broken any ground loop, and the fact that it didn't stop the hum indicates that a ground loop isn't the problem; in 5) when you disconnected the input cable from the sub, the hum stopped, which indicates that there was a ground loop which was broken by disconnecting the cable.

Since disconnecting the cable TV lead(a common ground loop source)didn't help, a ground loop isolator for the cable TV shouldn't help. You might try an audio frequency ground loop isolator such as this Xitel item between the receiver and the sub. However, the fact that the cheater plug didn't work, as mentioned above, raises a question as to whether this would be helpful.

I don't think this is your problem, but I'll post what worked for me....

I had a hum whenever my AVR was connected to my plasma via HDMI. Turns out, they were on seperate circuits. When I plug the sub/AVR/and Projector all to one circuit= no hum. I haven't tried the plasma on the same circuit, it's on a dedicated circuit installed after the house was built above the fireplace.

I happened to find a "THX certified" Monster cable for real cheap and tried it, no difference from my $2 Monoprice cable.

Thats one of the things that has been so frustrating...everytime i read something that makes sense (cheater plug for example), i run home and try it and get no results.

My daughter wanted to watch the half blood prince bluray last night so i fired up the sub to the same nasty buzz. I decided to try reinstalling the grounding screw and it worked, at least for last night. I'm going to have an electrician come over after christmas and look at a few things.

I had a problem with a hum on my subwoofer. Here is the symptoms I had:


I ended up buying the axiom ground isolator (cable company had no clue what I was talking about. However, My cable company actually reimbursed me for the cost.

I'll throw in my strange story. When I built my home theater closet I had two seperate dedicated circuts run to it. One circut handles all of the computer equipment, the other handles all of the AV gear. I never noticed a hum at all through my M80's after I purchased the Emotiva until we were giving a presentation one day and I was sitting about 4 feet from it. Once the customers left I tried sitting back in the captians chair, and sure enough I didn't notice it from that distance. But it bugged me enough that I decided to try to get rid of it.

The first thing I tried was unplugging it from the AV circut and putting it on the room circut. The hum completely disappeared. What's strange to me about that is that both sets of dimmer lights, the air conditioner, and the mini-refrigerator we have in that room are all on that circut. I would have thought if anything those would have caused a problem, not my other electronics. Also, when I had the EP800 plugged into that circut it never experienced any sort of hum, so why did my M80's?

Just a thought...

Do you have a computer, wireless internet or a cellphone nearby your home theatre room. Could this cause any type of interference/hum with the subwoofer/home theatre system?

My house is an electronics jungle
6 tv's
5 computers
4 cordless phones
3 cellular phones
2 internet routers
and a partride in a pear tree!!

LMAO... perfect!

Someone needs to write a guide on sub set up troubleshooting:

I suggest they call it "To Kill a Humming Sub".

House, it's funny you mention cellphone interference. When I got my new electric wheelchair earlier this year, it came with two warning tags (that weren't supposed to be removed) stating that a cell phone should not be operated around the wheelchair because it can cause the wheelchair to drive out of control. Pretty absurd seeing that it's virtually impossible to not be around a cell phone that isn't in use these days.