Hi all-

i recently acquired an a/d/s/ center (cheaply) to use with M3Ti mains. i noticed that despite a claim that the center is shielded, if it is set on top of my TV it distorts the picture. What makes a speaker "shielded" for video purposes? Is there a particular material in the cabinet, or is there a shroud or surround on the magnet/voice coil assembly?

Thanks- Bill

Hi Bill,
Your a/d/s center obviously isn't shielded. An extra magnet is usually added that counteracts the spurious force fields of the speaker's magnetic assembly. Ian might have some additional information on this matter.

Years ago, a special metal called mu-metal was used to shield magnetic phono cartridges from the radiated fields of the turntable motors. But it was much too expensive to use for speaker shielding.

II recall publishing an item in the very early days of Home Theater (early 1980s) about using a sheet of "cold, rolled steel" that you could place under a speaker to prevent interference with the picture tube. I'll look in my files and see if I can root out the gauge of steel you had to use. . .

Alan Lofft
Axiom Resident Expert

Thank you, Alan. i'm going to do a little looking into this issue and then turn the thread to the home theater list where it would probably be more appropriate.

Bill