Help with Subwoofer "Humming" and Ground loop isolator? (1 Viewer)

[Geardaddys]

First post on the forum.. I recently bought a new television (Samsung LN46 A550) and a Sony Blue ray player to use with my old surround sound system. (Kenwood HTB 503).. I've never had a lick of trouble out of the sound system, but after hooking up my new TV, adding the Blue Ray player, and changing out my verizon FIOS box for a HD box (Lots of changes, I know) I now have an intermittent humming noise coming from my subwoofer. The hum goes away when I disconnect the subwoofer cable that goes to the receiver. It also diminishes with a reduction in volume, and crossover changes on the back of the sub. I've done a good bit of reading on ground loop isolators, and bought one from radio shack today. In reading the back of the package it says "Do not connect the isolator to speaker or video cables".. hmmm.. I was under the impression that the isolator connected in-line with the line out cable that runs to the sub? I don't think that I can use it anywhere else in my system as all of my connections are digital coax/hdmi/toslink..

soooo.. long story longer (sorry!).. Here are my questions:

A. Can I use this ground loop isolator (Radio Shack 270-054) in line with the "line out subwoofer" jack at the back of my receiver?

B. The line out at the back of my receiver is only a single RCA jack. The isolator is designed with 2 input/outputs on each end.. Radio shack dude sold me 2 Mono/Mono plug adapters that combine the two plugs on each side of the isolator into one RCA plug.. Do I need to use these, or should I just use the white or red plugs of the isolator?

Thanks for any suggestions for a home theater noob.. I'm certianly not a audiophile, just want to have "ok" surround sound without this annoying BUZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ

Thanks!

John

 

[brandonchenry]

try putting the isolater inline and see if it works. no need to combine the pair, just use one side (red or white). if it works- great! if not, back to the drawing board. nothing bad will happen by just trying it.
i took a CEDIA class on ground loops, so I have some class info stashed somewhere. if your isolater doesn't work, we will keep troubleshooting it.

 

[Geardaddys]

Thanks much Brandon, I'll give it a shot and see what happens. Ive made so many changes I could be in for some serious troubleshooting if this isolator doesn't work.. More later, and thanks again!

 

[Geardaddys]

Ok, update on the hummming.. I've been home for a few days and have had time to try a few things..

One thing that I've noticed is that the sub seems to hum when started up from cold. The hum diminishes after a a few minutes. It also goes away when I unplug the line that goes to the receiver. I've tried several things to make this go away with no luck.

1. I replaced the cheap subwoofer cable that was going from the RX to the speaker with a higher quality shielded one.. No difference.

2. Added ground loop isolator in line to the sub. The sub doesn't have a grounded plug, so I didn't think this would help, and turns out it didn't.

3. Tried the sub in 3 seperate electrical outlets... Same result in each..

4. Replaced low end surge "suppressor" with a higher quality surge "protector"..

I'm bummin' because I really figured that the combination of all of these changes would for sure knock this problem out! Last week when I made my initial post, I didn't realize that the hum would dissapate after a few minutes because I was shutting the sub off as soon as it started with the humming..

Wondering if this is a sign of an aging/failing unit?

Thanks for anymore suggestions!!

John..

 

[Citizen87645]

I was chasing a ground loop six ways to Sunday and finally got one of these:

Buy Ebtech 2-Channel Hum Eliminator | Noise Gate & Suppressor | Musician's Friend

 

[Geardaddys]

Cameron,

My entire HT setup has only one component (TV) That has a grounded plug.. I'm not real swift when it comes to electrical problems, but is it possible to have a ground loop issue with only one grounded plug?

My gut feeling is that the fact that the sub humms for the first minute and then completley goes away is telling of something within the sub.. No idea what however...

 

[rob williams]

I had the same type of problem. It turned out to be something with the coaxial cable going to my cable box.The cable company gave me some type of filter{ground loop} that goes between the in coax cable and cable box. The problem is now gone. I would also double check all of the rca cable connections to make sure that they are all tight.

 

[brandonchenry]

cable boxes are notorious for introducing hum. Make sure you rg6 coming into the house is grounded. also check all of your coax connections to make sure the connectors are tight.
Check this PDF out. it is an outline from a CEDIA class i took on ground loops.
http://www.jensentransformers.com/an...%20seminar.pdf

 

[Geardaddys]

Ok, I just turned on the system and waited until the hum started.. Unplugged the cable (coax) from the wall and the noise continued.. also continues after the power is disconnected from the cable box.. I think that the noise is independent of all but the receiver and the sub.. Since it goes a way after a minute or two, I'm inclined to deal with it for now.. just irritating to have a new Theatre setup not working 100 percent!!!

 

[brandonchenry]

yeah, pretty weird it is only on start-up

 

[drobbins]

I had a ground loop between my receiver, sub, and projector even thought they are on the same circuit. This cleaned it up nicely. If you decide that it could be a ground loop bugging you, give one a try.

 

[RTS100x5]

Hello , here is a less expensive in-line solution than the hummx whatever
Audio Ground Loop Isolator RCA F/F Incl M/M Pigtail | Distributed By MCM | 50-9041
Ive used them they work great problem solved

 

[Philip Hamm]

Highly recommended. A few years ago a new fridge introduced a hum to my separates system, the Ebtech hum eliminators completely took care of the problem.

 

[Mendoza]

I'm also having the same problem. It looks as if some good responses have been provided so far, but I came across this link on eliminating hum from the company (Axiom) I ordered the speakers from. Of course it directs you to possibly buying Axiom's proprietary ground isolator (and also links to Radio Shack) but those devices, if necessary, can be got many other places. I haven't had a chance to begin assessing and fixing the problem but the info in the link is concise and probably worth checking out:
Tips: Eliminate Hum - Axiom Audio

 

[Geardaddys]

Thanks for all of the tips! I've tried the Ground loop isolator without any luck.. My hum only lasts for about 45 seconds while the Sub warms up when it is cold.. goes away and works great after it warms up..

Still not sure what that means, but I don't think that it is a ground loop issue at least with my situation..

 

[Bazzle]

My guess is the power supply transformer built into the powered sub.
The hum from the laminations is amplified by the enclosure (tuned for freq around 50-60hz)
When it warms slightly they close up and mech noise reduces.
Ive heard it on a couple of subs.
ie" wharfedale, B&W

If it goes away I would say you will prob forget it exists after a few weeks.

Bazzle