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I'm confused about shielding.


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8 replies to this topic

#1 of 9 OFFLINE   KellyR

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Posted November 24 2003 - 11:54 PM

When I think of shielding, I think of higher end wiring that has te rubber coating and the sheidling underneath. I thought that when people on the forum were talking about shielding, this was what they were talking about until someone mentioned having their speakers shielded. Can someone explain shielding to me. Thanks.

#2 of 9 OFFLINE   Chu Gai

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Posted November 25 2003 - 12:18 AM

Your speakers have magnets and this field varies as the speaker is played. The varying magnetic field that is generated can interact with the picture shown on your TV. Speakers that are shielded prevent this interaction from occuring hence you can place your speakers close (like the center channel on top) to your TV without any degradation of the image. If you've got a very strong magnet, you can observe this by moving it close to your TV. Very oversimplified.

#3 of 9 OFFLINE   KellyR

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Posted November 25 2003 - 12:27 AM

And wat can be done (besides moving the speaker further away) to remedy the situation?

#4 of 9 OFFLINE   Jeff Gatie

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Posted November 25 2003 - 12:37 AM

Quote:
And wat can be done (besides moving the speaker further away) to remedy the situation?


You can buy shielded speakers. Most speakers designed for Home Theater come shielded, certainly any speaker billed as a "center". This is not much of a problem with regular HT speakers, but it does raise an issue if you want to place your subwoofer close to your TV as most subs are not shielded.

#5 of 9 OFFLINE   JamesCB

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Posted November 25 2003 - 12:41 AM

Quote:
and this field varies as the speaker is played


Chu, I thought the magnetic fields were present whether the speaker is active or not. Do the fields change as the speaker is in operation?

#6 of 9 OFFLINE   Chu Gai

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Posted November 25 2003 - 02:44 AM

It certainly is present as at all times and when the speaker is played it also varies. Hey, it was a quick answer on the first cup of coffee! Now who knows what they use for shielding?

#7 of 9 OFFLINE   brentl

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Posted November 25 2003 - 03:01 AM

You can also shield your speakers if need be!

Brent

#8 of 9 OFFLINE   Cees Alons

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Posted November 25 2003 - 04:05 AM

They may use metal (preferably mu-metal) for shielding, but they also use (an)other magnet(s) to counter the speaker's one.

And although the field around the coil will indeed vary as the driver is played, I don't think the field of the big magnet, which is what disturbs the TV, will change noticeably.

And, Kelly, of course you were right about that wire.


Cees

#9 of 9 OFFLINE   ChrisWiggles

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Posted November 25 2003 - 04:56 AM

Shielding for wires and speakers are both shielding, just for different purposes. Wires can(and do) emit interference, but it's very very small for interconnects. Their signal is very small, and susceptible to outside sources of interference affecting the signal. This shielding, such as in a coaxial cable keeps interfering fields OUT of the wire. The speakers are shielded so they dont emit as much and mess things up that would be particularly susceptible (usually CRT TVs.)





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