Sheilding TV from Speakers

  • Thread starter Thread starter getuhgrip
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getuhgrip

getuhgrip

Bring Back Transfat!
Guy at work's got a new set of speakers mounted within 1" of his TV and is experienceing some color distortion in the corner of the screen.
What kind of materials are effective in sheilding against the speakers magnets?
 
The stuff is called Mu-Metal. Nothing else I know of works for magnetic shielding, and I have no idea where (or if) you can buy Mu Metal. The cheapest thing is to get better shielded speakers if they have to be that close to the CRT, or else replace the CRT with one of those new Panasonic 19" flat panels, they're only about $1600, :=)
 
Mu metal? Come on guys.:rolleyes:


Mu metal is very expensive and very overkill.

You can use sheet metal if you wrap it most of the way around the speakers (see attached picture). You can do this yourself or a sheet metal shop can do it for cheap. Just leave some room to glue felt or thin foam on the inside.

If you go to the scrap yard and find a couple of appropriately sized L shaped pieces of steel say 1/4" thick or make the L out of flat stock, that will work as well. The point is to redirect the bulk of the magnetic field lines through the metal.

barefoot
 

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Hey Barefoot, thank you for making my day! (No, I'm NOT from New York and that WASN'T sarcasm, I consider any day made when/if I learn something...
I've been in the tech fields of one kind or another for 38 years, and magnetic shielding was always one of those things that was "magic" - I bought into the Mu Metal thing when I was learning about mag tape recorders and head shielding, and (dumb) never questioned the old wives tale about nothing else being able to shield against magnetic radiation. Your post just caused me to do the following experiment, at least 30 years overdue: I have one of those "150 lb" pickup magnets that is at least as strong as any good speaker magnet, and a piece of 1/8" scrap steel plate about 14" x 16", and I just now brought both of them into my office and moved the magnet just close enough to the computer monitor to cause it to start "wierding out", (about 5" away, same distance as my KRK passives can get) then I inserted the steel plate between the two, without changing any juxtaposition, and the distortion disappeared! Then, I let the magnet grab the plate and moved it right up against the monitor, and only saw a slight discoloration, if anything. MONDO COOL! My next step in this vein will be to see if two monitors 1/4" apart will still show sync bars if not synced to the same video source -

So, thanks again, and I hope your day was as good as mine... Steve
 
knightfly,

Cool, I'm glad it worked out for you.

Yeah, Mu Metal has excellent magnetic properties, but the cost is so high that it really only makes sense in critical applications like precision manufacturing and research devices.

CRT's are actually pretty robust. For example, they don't care which direction they're facing, i.e. the earth's magnetic field isn't a problem.

Just remember that curves in the shield are better than corners and the thinner the shield, or the closer the placement to the CRT, the more you have to sort of emulate the shape of the field lines in order to channel them through the shield.

barefoot
 
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