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.

Mo, I imagine that anyone would be moaning with something as big as the EP600 humping them.

. That's thumping. Have you been taking lessons from Peter?

Hey, it wasn't me who left off the t.

I'm rolling on the floor from that one!!

Wow JohnK you didn't give Peter a chance!
Looks like he has some good competition

I do sleep, occasionally, so I can't get all of 'em.

Hmm, what were you all knackered from?

Just normal daddy duties. Sometimes bedtime stories are more effective at putting me to sleep than the kids.

(The etymology of 'knackered' is rather intesting, btw.)

I've got a good priest I can send up your way to get rid of your ghosts.

This is interesting. Now John, Peter, myself, and mojo have had this issue with their EP subs. I've only noticed it during thunderstorms in the area and unplugging my power chord for a minute and plugging it back in got rid of the noise.

I've never heard of this problem with any other subs on the market?

this has also happened to me as well, a quick reset of the sub takes care of the thumping.

thanks to the custom search feature I found this thread. MY ep-500 has a slight hum and vibration.

Originally I was having a hum with all speakers. I unscrewed the chasis ground screw on the back of the sub a bit and it stopped the hum comming through the main speakers.

I thought it was fixed, but upon closer inspection I noticed a hum and a slight vibration comming from my ep500 still.

I am on hold with my cable company trying to get through with someone to get a ground isolator installed

EDIT: may cable company must be flooded with phone calls or something, everytime I get through the automated menu The stupid thing hangs up on me.

Welcome to the world of customer service circa 2007.

Might be faster to just order one from Axiom.

hmmm. Here is the situation:

Chasis ground screw loosened a bit on the ep 500 and cable box plugged in= slight hum in subwoofer.

Chasis ground screw loosened a bit and cable box unpluged= slight hum turns in to a LOUD ROAR.... ?

Chasis ground screw tightened all the way back to normal with cable box plugged in= slight hum

Chasis ground screw tightend all the way back to normal with cable box unplugged= no hum.

My cable company is coming out saturday and I will have them install a ground isolator. Sounds like a ground Isolator on the cable box + chasis ground screw tightened into original setting will eliminate my ground loop problem... what do you think?

what I don't understand is why the hum gets SO FRIGGIN' LOUD with the cable box unplugged from my receiver and the chasis ground screw loosened...

WEIRD!

If all else fails I will buy the axiom ground isolator, but I am going to try and convince my cable company that it is there fault (well it is) and see if they will do it free of charge... (hey it's worth a shot )

Sure, if unplugging the cable stops the hum, then that's the ground loop route that has to be cut.

Thats what I thought, I just didn't understand why unplugging the cable box made the hum louder if the chasis ground screw was unscrewed.

Well my cable company was aboslutely no help. The claimed the problem was with my system, even though unlpugging THEIR cable fixes the problem.

An audio video store down the road from me sells what is called a magic box (Mondial Antenna Ground Isolation Circuit), supposedly made by klipsch: link here.

The product is $110!

I think I will be ordering the ground isolator from axiom for $48.

I am trying to find a cheaper fix than $50, but if I need to I will buy the isolator from axiom.

Tried to edit my post buy too much time had elapsed.

I also might add the cable guy told me that the problem might be that I am using a 'denon' receiver- he has never heard of that brand. He said that he has a sony receiver at home and he reccomends that model! According to him my receiver may be the problem.

Also he said a hum is normal on all speakers, just typically not at low volumes or off completely.

He said when he cranks his speakers up to "max volume" there is a hum/hiss/distortion- and ALL speakers have this problem at higher volumes.

I responded by telling him that the problem might be my speakers since I purchased them from some internet only company that many people have never heard of...

LOL

Geez. That must have a been quite a pleasant discussion! That type of aggravation is not worth 50$. Damn these monopoles and the resulting customer service.

For some reason the issue seems to have resolved it self for the most part.

When I loosen the chasis ground screw now the humming pretty much completely stops.

If I get right up to the subwoofer and touch it, I can feel a SLIGHT vibration, and hear a VERY VERY FAINT hum.

If it stays as is I will be fine, if the problem reverts to how it was I will definitely be buying that ground loop isolator from axiom

BTW, you are supposed to remove it completely, not just loosen it.

hmmm, brent from axiom just told me to loosen it abit. I did remove it all the way when I was testing things out earlier... removing it all of the way produced the same results as just unscrewing it a few turns.

I like keeping it in there so I don't lose the screw-unless there is some reason that I should unscrew it all the way...

Good. As long as it comes from Axiom, it's OK. Sometimes ground pins are close to high-voltage elements and it is hard to garentee that there is not a bit of induction still happening.

Well I ordered the ground isolator from axiom last night. I sure hope it solves my problem. I just hope that the hum comming through my sub is not somehow comming from the cable box itself (which is converting the cable signal to a digital signal). If this is the case the ground isolator will do me no good... I think.

On a positive note, I called my cable company and asked to speak with a tech support manager.

I explained the problem, and was told that if this $48 dollar device will fix my problem then they will credit my account for $48 (It took a slight amount of discussion before they came to this conclusion)

so if it works, I will be making a call to the direct number I was provided for my $48 credit!

Please keep us informed on this.

For what it is worth, I had the same problem with my EP500. The hum disappeared when I plugged my gear into surge suppressors.

I got my ground isolator from axiom via fed ex this morning.

The hum is completely gone!

No more unlugging the subwoofer to watch cable!

I did a quick flip through on several HD channels and the picture did not seem to be changed at all.

During breakfast the channel that was on cut out VERY briefly (like a cd skipping) twice. I changed the channel and it hasn't happened again.

Hopefully The ground isolator isn't somehow interfering with my cable feed.

I will call my cable company monday to get my $50 credit!