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Discussion Starter · #1 ·
Sorry for asking this question as there are tons of threads on this already (I know I read them!).


I'm getting a low level hum out of my sub. It's not always humming. For example, last night while watching the Lakers game, it would do it sometimes. It was very consistent though. Meaning if it the sound happened, I could rewind the game and make it happen again.


Disconnecting the subwoofer RCA cable stops the hum. That means it's not from the outlet, right?


I guess my question is are group loop hums constant? Or can they be like my sound is, based on the broadcast?
 

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Quote:
Originally Posted by ejhuzy /forum/post/18169244


Sorry for asking this question as there are tons of threads on this already (I know I read them!).


I'm getting a low level hum out of my sub. It's not always humming. For example, last night while watching the Lakers game, it would do it sometimes. It was very consistent though. Meaning if it the sound happened, I could rewind the game and make it happen again.


Disconnecting the subwoofer RCA cable stops the hum. That means it's not from the outlet, right?


I guess my question is are group loop hums constant? Or can they be like my sound is, based on the broadcast?

Try disconnecting you're cable/sat coax going into your box and see if the hum goes away. If it does that's a classic ground loop. You can try using a cheater plug (3 prong to 2) for your subs power cord.
 

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Sounds like it is the rca cable to the sub woofer,i had this issue about two months ago. and when i got a new cable the hum went away. so,if you unplug the cable and the hum stops,it sounds like a cable issue.
 

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Discussion Starter · #4 ·
I should have mentioned that I don't have cable, I have DirecTV.


Also, I've been using the subwoofer cable for 18 months with no issue. The hum is new in the last month or so. Making me think I added something that is causing the hum or worse the sub is broken.
 

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If absolutely nothing in your setup has changed, it could be something in the environment changed.


Perhaps now your cable is picking up the 60 Hz. cycles from electricity for some reason. The cheapest and simplest solution is to swap out the RCA cable with a shielded one. You can use RG6 shielded and F to RCA adapters if necessary.
 

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Discussion Starter · #6 ·

Quote:
Originally Posted by jpmst3 /forum/post/18169422


If absolutely nothing in your setup has changed, it could be something in the environment changed.


Perhaps now your cable is picking up the 60 Hz. cycles from electricity for some reason. The cheapest and simplest solution is to swap out the RCA cable with a shielded one. You can use RG6 shielded and F to RCA adapters if necessary.

I think this is the cable I have. Is this one not shielded?
 

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Quote:
Originally Posted by ejhuzy /forum/post/18169499


I think this is the cable I have. Is this one not shielded?

No, not unless is specifically says shielded.


Long runs of RCA are inherently prone to picking up all sorts of RF interference.

I don't know for sure that this is what is happening in your case. But, the cable is the simplest to check.
 

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Quote:
Originally Posted by ejhuzy /forum/post/18169499


I think this is the cable I have. Is this one not shielded?
Of course it is shielded!


Can you not read the link you, yourself, provided??
"Features -

Connectors: single RCA Plug(male) to single RCA Plug(male)
24k Gold Plated 8-cut connectors ensure long-lasting, corrosion-free connections
Fully molded connecters provide excellent strain relief
High-quality coax wire with copper braid shield reduces unwanted noise and distortion
Gold-plated, RCA connectors give you solid, corrosion-free contact
Easy installation with non slip rubber grip
Improves digital signal delivery as compared to standard RCA type audio cables
True digital signal maintained by high materials and connectors
99.999% Pure Copper Non-OFC conductor
High-density double shielding for max rejection of EMI and RFI Capacitance: 22PF per foot"
 

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A group loop...hmmm. I've heard that you can get a group loop if you go to the Green Door in Las Vegas. Mind you I've never been there, but I've heard stories.
 

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Discussion Starter · #11 ·

I just noticed I typed group instead of ground. Not once, but a number of times!



I did read the web page and I did see that it said "shielded". I just wanted to know if there's something better I should be using. The blue jean cable page has a sub cable for $90. I'm weary of the whole spend more get more theory on cables.
 

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Quote:
Originally Posted by ejhuzy /forum/post/18169860


I'm weary of the whole spend more get more theory on cables.

The cheapest RCA-RCA cable will work as well as any other. The Monoprice cable you have is just fine!
 

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Discussion Starter · #13 ·

Quote:
Originally Posted by cavu /forum/post/18169869


The cheapest RCA-RCA cable will work as well as any other.

So, back to my original question then. Does a ground loop typically present itself as a hum based on source content? Meaning, should I either always hear a hum or no hum? Right now I only hear it sometimes.


Another thing I noticed too. If I moved my cross over to 30Hz, it went away (with the cable still attached).
 

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Quote:
Originally Posted by ejhuzy /forum/post/18169289


I should have mentioned that I don't have cable, I have DirecTV.

Also, I've been using the subwoofer cable for 18 months with no issue. The hum is new in the last month or so. Making me think I added something that is causing the hum or worse the sub is broken.

That is why I said cable/sat coax. Sat(satellite)
 

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Quote:
Originally Posted by ejhuzy /forum/post/18169879


So, back to my original question then. Does a ground loop typically present itself as a hum based on source content? Meaning, should I either always hear a hum or no hum? Right now I only hear it sometimes.

If you mean source "program" content - then no it's not a ground loop! But some programing along with volume limiting (compression) might make background hum more apparent. My STB has a volume limiting mode "Narrow" and when I fast forward through commercials it gets all confused.
 

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Quote:
Originally Posted by ejhuzy /forum/post/18169879


So, back to my original question then. Does a ground loop typically present itself as a hum based on source content? Meaning, should I either always hear a hum or no hum? Right now I only hear it sometimes.


Another thing I noticed too. If I moved my cross over to 30Hz, it went away (with the cable still attached).

Sorry man, out of haste I did not follow your link. If it is indeed shielded then it is not the cable.

I guess that was pointed out in a less than tactful manner.


You may indeed have a ground loop of some kind.


When I experienced a loop it would often change depending on other devices in the house, ala refrigerator, etc.
 

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Quote:
Originally Posted by ejhuzy /forum/post/18169244


I'm getting a low level hum out of my sub. It's not always humming. For example, last night while watching the Lakers game, it would do it sometimes. It was very consistent though. Meaning if it the sound happened, I could rewind the game and make it happen again.


Does it only happen sometimes? Like live broadcasts or tapings of live events? It could be a sound in the actual audio signal, being picked up at the venue. Try turning the volume up and down and see if the volume of the hum changes.


When they record live (like the Olypmics right now, or basketball games, or political speeches, or news stories), you often get sounds. During the SOTU speech, I could clearly hear every time Pres Obama plopped his hands on the podium. I hear hums from nearby trucks/vehicles or a fan or a power generator in news broadcasts - they record on location live and don't touch up the audio, filter things out.


So it's very possible that, because it seems to be happening at specific times, and because you can rewind and reproduce it, that it's in the broadcast itself.
 

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Discussion Starter · #19 ·

Quote:
Originally Posted by jpmst3 /forum/post/18170594


Does your sub have a grounded (3-prong) plug?


If so, you could try a cheater plug there as a temporary solution.


If not, we can proceed from there.

The sub's electrical plug is only two prongs. So the cheater is out.

Quote:
Originally Posted by cyberbri /forum/post/18170912


Does it only happen sometimes? Like live broadcasts or tapings of live events? It could be a sound in the actual audio signal, being picked up at the venue. Try turning the volume up and down and see if the volume of the hum changes.


When they record live (like the Olypmics right now, or basketball games, or political speeches, or news stories), you often get sounds. During the SOTU speech, I could clearly hear every time Pres Obama plopped his hands on the podium. I hear hums from nearby trucks/vehicles or a fan or a power generator in news broadcasts - they record on location live and don't touch up the audio, filter things out.


So it's very possible that, because it seems to be happening at specific times, and because you can rewind and reproduce it, that it's in the broadcast itself.

Cyber thanks for the ideas. Last night I watched Surrogates on blu-ray and heard the sound. I also heard it while watching Braveheart on TNT.


Turning up the volumn on the sub makes the hum louder.


All the threads talk about the hum coming from the cable TV. I have satellite. Can satellite create the same problem? I really want to fix this.
 

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Quote:
Originally Posted by ejhuzy /forum/post/18172610


The sub's electrical plug is only two prongs. So the cheater is out.




Cyber thanks for the ideas. Last night I watched Surrogates on blu-ray and heard the sound. I also heard it while watching Braveheart on TNT.


Turning up the volumn on the sub makes the hum louder.


All the threads talk about the hum coming from the cable TV. I have satellite. Can satellite create the same problem? I really want to fix this.


It's possible. That is way I have said to try disconnecting the cable in coax at you're satellite box and see if the hum goes away
 
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