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

I’m hoping someone out there can help me out with this humming problem. It’s starting to drive me nuts.
I have an axiom system with the EP500 sub, I’ve been getting that 60hz buzzing for quite awhile now, it’s to the point that I only plug the thing in when I want to watch an action movie and I know the buzz will be drowned out by everything else.
I’ve done some research and tried some things but everything so far has failed. Here’s what I’ve tried.
1) Remove ground screw (worked for a little bit but hum came back)
2) Bypass the ground by plugging the cord into one of those 3 to 2 prong adapters (made it worse)
3) Unplug cable TV from cable box to check for interference…no change
4) Plug into different outlets .. sometimes gives temporary relief
5) Unplug the input cable from sub…this works which makes me think it isn’t my electric..?
When I was trying these methods I ran across something really strange…I noticed that when I walk towards the sub the hum gets louder the closer I get.
I’m all out of ideas, the sub cable I’m using came from monoprice and I believe it is shielded. I’m willing to try about anything EXCEPT ordering a cable from monster! :P
Any ideas?

Hi iammongo,

Can you disconnect the subwoofer from the system all together and with all your other equipement off just plug the subwoofer into an outlet and turn it on (no subwoofer cable attached)? Does it hum, buzz, pop or make any other sounds?

His #5 seems to indicate what removing the input from the receiver does indeed stop the hum. So it is a ground loop, just an extra pesky one.

I'd say, while it is humming, start unpluging things from each component, and then components themselves from the wall. When it stops humming note what you just unplugged. You can then try plugging some of the other stuff back in, and see if it does not return. Report back here with your findings for some ideas.

Will do that....thanks for the advice

If it's happening without anything attached to the sub other than power, it's a problem with the amp. Call or email Axiom.

nope, with the sub just plugged in there is no noise

Is the subwoofer brand new? How long have you had your entire setup? Have you added any new components or cables to your system? Has the hum always been present?

If you can borrow another sub cable off someone I would also recommend swapping out the Monoprice cable. I have never used a Monoprice sub cable but with other cables I have used from them the build quality can be hit or miss. It is always possible the shielding could be inadequate or the cable defective which is inducing hum. You seemed to have tried everything else.

I just bought a ground loop filter from Axiom and my problem went away.

Could the hum come from a recently installed light dimmer or nearby fluorescent light? Or do you recall this problem starting after getting a new appliance like a refrigerator?

Good call davew.

no new appliances but there have been times when the hum went away and turning on a lamp would make it start.

I'm not so sure the filter would work on the cable line...i unplugged the cable from the cable box so there was no connection and the hum didn't change at all.

Whenever I had the very same issue that drove me nuts for several days the problem ended up being the whole house grounding rod, specifically the ground wire from the rod to the electrical meter box ... just for grins and giggles I replaced the rod and installed new wire and connectors and made sure the outside cable coax splitter and box was properly grounded, haven't had any issues in the past four years since I did this.

IMO to nip a grounding issue in the bud you need to backtrack from the primary grounding source back to your components and not visa versa.

I'm definately going to try a different sub cable. The system is about 2 years old. I have all axiom speakers and an onkyo 750 reciever. The hum has been off and on always. I have removed and then replaced the ground screw several times. sometimes it works better with it in and sometimes it's better with it out.

the hum has been around off and on for about 6 months. just recently it has been getting louder and louder.

Thanks for that advice...i'm no electrician so i'll have to ask the dumb question here....can i just detach the wire from the ground spike (i do know where it is :P ) and replace it with no risk of death? :P

Sure can. And whenever you do that, make sure that you have a good contact that is metal to metal, scrape paint to do this if you need to.

Oh ... no risk of death, I don't believe.

I'm not an electrician, but I have an older house that doesn't have all of this, but I'm learning because I've had electricians giving me estimates of what it would take to install a 3 wire (with ground) system in my house, starting with the box. There is currently a ground wire running from the box to the water pipe where it enters the house.

They will have to install a grounding rod from outside to the new box. They also said that there are 2 grounds, the primary ground is the one that runs to the water pipe and the secondary ground is the grounding rod outside.

If you detach the grounding rod ground, at least it isn't the primary ground, but your house is no longer "in code", and you may have other issues, such as insurance waivers that certain surge suppressors provide when the house is properly wired.

I'm certainly not trying to imply that the grounding rod or any ground connections should ever be taken out, I'm merely saying that the OP may want to inspect and replace any wires that looks questionable and/or tighten any loose connections.

I misread his comment. I thought he wanted to remove the ground, not just replace the wire.

10-4...

I was wondering where you got that idea from but I didn't want to say anything with the holiday spirit and everything going on you know.

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.

Wow, Cam, I agree with you. Nowadays, this should be considered a major design flaw...

It seems that most people are designing equipment to reject the GSM devil now. My older Alesis powered monitors I have on my computer can channel the devil's chatter, but no matter how close I have my phone to my Pioneer receiver it never makes a peep.

I have a tough time believing regular household gadgets can cause this hum. I've had powered subs in my house since the mid 80s. Believe me there are plenty of the listed gadgets here and I've never had a hum problem from such a source.

Not that I haven't had ground loops but certainly not caused by cell phones and such.

I was only speaking in the general case. Most of the time GSM phones are not "talking", only during a call or data transfer. GSM interference has a very distinctive sound, as does a 60 Hz hum; they are both completely different beasts.

Sorry Chris, I meant this list of stuff.

6 tv's
5 computers
4 cordless phones
3 cellular phones
2 internet routers

You're missing 7 dwarfs...