Axiom Home Page Forums General Discussion Advice from Axiom Owners Speaker and subwoofer hum

I strongly recommend to all those out there that are experiencing hum on their speakers or subwoofers to install an in-line ground isolator on their cable feed. And I recommend this even for those that have cable installed but may not be using it.

I've had a slight hum on my EP600 since I bought it. I had cable outlets installed and wired but did not have my cable connected to any of my components. I recently had my cable service turned on and the hum on my 600 continued and it also appeared on all of my other speakers. After installing the ground isolator, the hum disappeared.

The very peculiar thing that I've noticed (and cannot readily explain) is that if I disconnect the cable from my components and remove the isolator, the hum re-appears on my 600 (but not on any of my other speakers). If I install the isolator, the hum disappears.

Your cable company will supply and install this isolator for free. Just make sure that this isolator is not located on the cable branch that is providing you digital phone service.

I had a hum in my 600, 150 and 80's at one point, but removing the ground screw on the 600 resolved that problem.

That's the first thing I tried but it got worse. Even if it did work, I would have some hesitations about removing that ground screw.

Next time you have a storm, unplug your 600, re-connect the ground screw and plug it back in. I'd be curious to find out if you hear the thump. But make sure you unplug it first before re-connecting the ground screw.

The ground screw was removed based on the recommendation of Axiom, and it resolved my issue.

It resolved your thump during storms or just the hum?

Hi Mojo,

Just a note here on the cable companies. Based on my experience with Axiom customers, most cable companies and cable guys in the US don't know what a ground-isolating transformer is. One exception is Cox Cable, which is in New Jersey, who supplied a ground-isolating transformer for free to a subscriber, the only instance I'm aware of.

I hope Canadian cable companies are more knowledgable. Certainly all customers with hum problems should ask the cable installers about the subject.

The Axiom ground-isolating transformer has a bandwidth of 5 MHz to 1.3 gigahertz and causes no degradation of digital HDTV signals:

http://www.axiomaudio.com/groundisolator.html

Note: it can't be used with satellite dish systems.

Regards,

When I called Shaw cable about my problem, the service rep had no idea how to correct hum and had never heard of a ground isolator. So I was really worried that the service call that he set up would be a waste of time. Fortunately when he came, he was equipped with one.

I'll bet many just live with the hum and accept it as a fact of life.

If your cable company has no idea what you're talking about when you place the call, insist that they show up at the service call with an isolator. Or, buy one from Axiom.

The hum problem was something that occured back when I owned the Emotiva MPS-1 amp in January. Once I removed the screw it went away from all the speakers below my screen. I may try to put it back now that I have Odyssey amps.

The thumping was a different issue.

Late last night I was alone in the basement with all the lights and A/V gear off working on some stuff on my laptop. I got the heebie jeebies when I heard really low moans coming from the side of the room. I quickly realized that my 600 was humping. The weather was calm.

I'm not really concerned about this but it can certainly freak you out under the right conditions.