[John Stone]

On 12/16/06 11:33 AM, in article ,
"dizzy" wrote:

Trevor Wilson wrote:

"Bob" wrote in message
...
I am planning to build a centre channel speaker box using the same type of
single woofer/tweeter drivers as the surrounds. Was wondering what is
required in the way of shielding. The CC would be sitting about 6" above
the
54" HDTV. Thanks

**A 'bucking' magnet, of approximately the same magnetic force. Apply it to
the existing magnet. Then, cover the whole magnetic assembly with some soft
iron or, preferably, mu metal. Better still, follow Graham's advice.

That's some really bizarre advice. Would it not be easier to shield
it with some mu-metal?

You would normally use a magnet slightly smaller than the main one and then
a shielding cup over the whole magnet assembly. If you just use a bucking
magnet, you will effectively cancel the field to the sides but you'll
actually increase the stray field to the rear. Depending on the drivers in
question, aftermarket shielding kits are available.