A piece of steel or iron will have enough ferromagentic material to shield your tv. Don't use aluminum or tin. Put the steel/iron between the tv and the speaker and you will have no problem. Try it with a Cast iron pan from the kitchen if you want a proof-of-concept.
How to magnetically shield a speaker????
Help needed!!! Does anybody know how to magnetically shield a TV placed right above the floorstanding center speaker? The TV is on a firm movable platform (can go up to 4 feet high) with my center speaker right under it. I haven't chosen a projector yet, so I'm going to use my TV meanwhile. I saw a couple of links on this subject where they recommended to put the TV/monitor in a metal cage - quite a horrible vision to me. Is it possible to to obtain the same results using some thin foil or sheet? Thanks in advance. Mike.