Axiom Home Page Forums General Discussion Technical Questions Subwoofer hum - ground loop?

I'm almost certain I've seen this topic here before but I can't find it by searching. I have just hooked up my receiver to the TV, and when I plug the coax cable into the TV I'm getting a loud hum/buzzing from the sub. Seems like a ground loop to me, and I'm looking for suggestions on getting rid of it.
Is conversion of the signal from 75 ohm to 300, and back again, the first thing to try?

If you have an ep500 or and ep600 I would loosen the ground screw on the back first and see if that helps.

If that doesn't work I would purchase the axiom ground isolator.

It is $48 and eliminated my subwoofer hum completely. I even talked my cable company into paying for it after being escalated to a manager.

If you use resistors and rig up something yourself you may fix the problem but will probably lose you picture if you have any HD or digital channels.


more discussion here:
http://www.axiomaudio.com/boards/ubbthreads.php?ubb=showflat&Number=187122&fpart=1

If you have cable, you may want to make sure your incoming cable is properly grounded ... in my case, I ran a 12ga ground wire from the splitter (inside the plastic box in the pic) for the house down to the house grounding rod. Just a month or so ago I noticed a very prominent ground hum and went outside to check the ground, sure enough the wire had somehow worked itself loose from the rod and after securing the wire the ground hum disappeared.



Which reminds me, I *really* need to secure that ground wire to the house one of these days.

Rick lives inside the Matterhorn.

That would be my mancave Sean.

The rocks do look vaguely out of place for here though, whenever we first moved here we pondered what color we should paint 'em, and what exactly were these things anyway, until one of the good neighbors informed us that they were rocks and rocks don't get painted.

So we left 'em as is.

That's great advice--rocks don't get painted! I like it.

I just got the new 350, and I'm not sure if it has the ground screw. Will check when I get home. Also need to confirm that the cable is properly grounded where it enters the house. thanks.

When I added a second sub to my setup I started to get the ground loop hum. All I did was use an adapter for the electric cord...three prong down to two prong... and everything has been fine since! I used the adapter on the ssecond sub which apparently caused the problem.

I would not reccomend using a 3 prong to 2 prong adapter. There is a reason that the 3rd prong is there!

I had a ground loop problem with one sub, which loosening the ground screw would not help. The ground isolator fixed that problem.

When I had two ep500's for the weekend I noticed the ground loop hum slightly came back.

I loosened the ground screw on the second sub and it went away.

So for two subs I need the ground screw loosened on the second one + the ground isolator to eliminate the hum.


It can take a lot of trial and error to finally resolve a ground loop issue.



I would try the ground isolator from axiom- it works great

I seem to have resolved it. Traced the cable back to the nearest splitter and attached a 14ga. ground wire between the splitter and an electrical junction box that happened to be close by.
The hum is gone.

I'll put the ~$50 I saved into my next Axiom purchase, which will probably be a couple of M3s.