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Discussion Starter · #1 ·
Hi everyone. Could someone help me with a problem? I am trying to install an in-wall center speaker and the speaker itself NEEDs to be close to an active romex cable to be 'near' the center of the TV. I don't know if the romex is shielded and the speaker wire IS about 12" away from the romex, but not the speaker itself. The Speaker wire is not shielded; it's CL2 rated. Can anyone help on solutions? I've been told there will be a 60 cycle hum if the speaker is too close, but I can't find anyone else stating that; only speaker WIRE being closer than 12" would cause the hum. If anyone could help, I would greatly appreciate it. Thanx.
 

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Hum can be induced directly into the speaker. A speaker is essentially a magnet and coil of wire (voice coil); your amp modulates the current in the voice coil to generate a magnetic field that pushes against the magnet and makes it move. Think of those electromagnets from grade school science class... The live house wire can also induce an EM field, moving the speaker cone and causing hum. Can you hold the speaker up while playing and see if you notice any hum? Maybe you'll get lucky... As for possible solutions:


1. Shield the back of the speaker, using mu-metal or similar.


2. Since you have to open the wall anyway, see if you can move the electrical line out of the way. With luck there'll be some play, and you may be able to pry a staple or two out and just push it to the very back to reduce the coupling. Don't use a screwdriver to move the wire! Try a wooden dowel, broom or wooden/fiberglass hammer handle, or something.


3. If current flow is minimal there should be minimal coupling. I.e., don't plug anything into the circuit. (solutions, ask for you did, "practical" was word not used...
)


4. Move the cable (the expensive solution, but often not as hard as you might think).
 

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Discussion Starter · #3 ·
Those are definitely some options. I was just told of another one. Do you think this could possibly work? Wrap the Romex cable with a layer of aluminum foil? Unusual, but could it work? it would be easiest, obviously, but if it doesn't work; no point. Thank you for the help thusfar.
 

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Quote:
Originally Posted by rain2 /forum/post/18300971


Those are definitely some options. I was just told of another one. Do you think this could possibly work? Wrap the Romex cable with a layer of aluminum foil? Unusual, but could it work? it would be easiest, obviously, but if it doesn't work; no point. Thank you for the help thusfar.

if you have cut the hole install it and take a listen, if there is no hole wire it up and somehow support it where it will be installed, drywall won't sheild it, if you get a hum look for sheilding ideas otherwise you might be good to go.
 

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If you want to sheild it just go to your local electrical supply house and get sheilding tape...Scotch 3M-13 I think?? just wrap in around the romex and tape around it.


Seriously...the only problem is if you run them in parallel very close for a few feet or more... You can cross them with no problem and can even run them in parallel as long as you keep a foot or so distance between them.


I prewired my and built my HT and I did have a problem with hum on my Infinite Baffle sub...the sub's drivers are in the attic... I stupidly ran the subs speaker wires along side the subs amp dedicated power romex cable for about 5 feet(got in a hurry and didn't pay attention) ....I simply seperated them with about 10" of space and all is good...no more hum at all.


I don't think you have anything to worry about...just install and enjoy.
 

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Discussion Starter · #6 ·
wow, didn't know about shielding tape. I'll have to look. What type of electrical supply house should I look for(lowes? home depot? or maybe even radioshack)? I'm not familiar with any stores of that title around. Oh, I found out I did something stupid; knowing that I had a romex near the center speaker, I somehow, stupidly, ran another romex right in the middle of where the center speaker will be (it was for the recessed power so I didn't have to have a power cable running down my wall). I have some play with moving that cable, but the shielding tape sounds like it may solve my problems (at least peace of mind if I didn't have any problems to begin with). Thank you all for your suggestions. I will have to hunt around for that tape as it's the easiest to do for now. =)
 

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Discussion Starter · #7 ·
Well, installed the center speaker, but unable to test it right now (just moved the romex as far away as possible, but didn't full Mount the speaker yet in case I need to remove it and do something else). Will try testing once I complete my in-ceiling speaker installation and finally hook it all up to the receiver. Just gotta go through an obstacle course that is called the attic with 2' high blown-in insulation in my way....fun.
 
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