Help with Video shielding

[boead]

I have a Sony 36" XBR less then 2 years old. I had a bunch of M-Audio powered speakers around it for surround but recently swapped out the front main pair for an older set of Energy Pro22 speakers. These speakers are NOT shielded and are reeking havoc with the TV. They sound best just a few inches away on either side but they are producing all kinds of interference with the tube.

If I move them at least 18 inches away the effect is almost completely gone, at 24 inches it IS gone but now the speakers are almost 8 feet apart and it’s a problem. As I slowly nudge them closer the TV monitor starts to be effected.

My only option is to shield one of the two.

I can open the up the TV and run some sort of shielding down the sides of the tube as long as the shielding is thin and rollable (like foil wrap). Shielding the speakers will be much more involved. These Energy Speakers have enormous magnets within, I’ve never had such a problem like this before.

Where can I buy video shielding??

[therockman]

This question should be in the hardware section.

[-=Rudy=-]

From what I remember, you'd need something like 12 gauge steel to block a magnetic field (either around the magnet assembly, or lining the enclosure with it), or you'd have to buy something called a "bucking magnet" that you'd glue onto the back of the speaker's magnet. This creates an opposite magnetic field that cancels the other one out. Might check Parts Express (http://www.partsexpress.com) for bucking magnets.

[boead]

Originally posted by therockman
This question should be in the hardware section.

It is.

[boead]

Originally posted by -=Rudy=-
From what I remember, you'd need something like 12 gauge steel to block a magnetic field (either around the magnet assembly, or lining the enclosure with it), or you'd have to buy something called a "bucking magnet" that you'd glue onto the back of the speaker's magnet. This creates an opposite magnetic field that cancels the other one out. Might check Parts Express (http://www.partsexpress.com) for bucking magnets.

Great, your not the first to mention the bucking magnet. How will this effect the speakers performance?

How large do you think it needs to be?

[mudbone]

Originally posted by boead


It is.

Because I moved it from "Music."

mud-http://www.stevehoffman.tv/forums/attachment.php?s=&postid=459212

[boead]

Originally posted by mudbone


Because I moved it from "Music."

mud-http://www.stevehoffman.tv/forums/attachment.php?s=&postid=459212

In Music? I never really go there. Strange.


Oh well, how about an answer to the question.

[-=Rudy=-]

Originally posted by boead


Great, your not the first to mention the bucking magnet. How will this effect the speakers performance?

How large do you think it needs to be?

Far as I know, it shouldn't affect performance, as it's out of range of the voice coil. As for size, Parts Express may be able to recommend a proper size for your driver. I've never used them myself.

[John Simpson]

I once shielded the inside of an electric guitar using cooking foil. It worked brilliantly, the guitar was completly unaffected by buzzes and hums after that.
Could you line the inside of a speaker cab with cooking foil ?
I realise that a speaker magnet is much more powerful than guitar pickup magnets, so dont know if it would affect anything.

Anyway if it didnt work you could always roast the turkey in the cabinet :D

Merry Christmas All
John

[-=Rudy=-]

Aluminum foil would be good shielding for electrical noises (it's also used in coaxial cables), but since aluminum is not magnetic, it would not shield the magnetic field of the speaker. I think the minimum gauge of steel I've heard recommended for shielding was 12 gauge, and that's quite thick. (Thicker than sheet metal.)

I've never roasted a turkey in a speaker cabinet. Interesting. Wonder how you'd do the potatoes? :laugh:

[John Simpson]

Originally posted by -=Rudy=-


I've never roasted a turkey in a speaker cabinet. Interesting. Wonder how you'd do the potatoes? :laugh:

Maybe , grill them ? :D


(speaker grill )

[-=Rudy=-]

Now THAT is a groaner! :laugh:

[boead]

Originally posted by -=Rudy=-
Aluminum foil would be good shielding for electrical noises (it's also used in coaxial cables), but since aluminum is not magnetic, it would not shield the magnetic field of the speaker. I think the minimum gauge of steel I've heard recommended for shielding was 12 gauge, and that's quite thick. (Thicker than sheet metal.)

I've never roasted a turkey in a speaker cabinet. Interesting. Wonder how you'd do the potatoes? :laugh:

I pulled the speaker, its an 8" (EMS, Energy Systems) polly speaker with 25mm X 85mm magnet. Speaker is about 19 years old. It effected my Hitachi 19" monitor within 2 feet :eek: . I ordered a couple of sets of magnets and some 5-min epoxy.

I also found some Mu foil (http://www.lessemf.com/mag-shld.html) 16” wide roll, $19 per linear foot.

Could I wrap the foil around the magnet or does the inside of the cabinet need to lined? That’s not going to be easy or very cost effective at this point. I can wrap the magnet fairly easily with a layer of insulation between.

What do you guys think?

[petzi]

You might use mu-metal, that is a metal alloy specially designed to shield magnetic fields. I don't know where you might buy it, though.

http://en2.wikipedia.org/wiki/Mu-metal

[boead]

Originally posted by petzi
You might use mu-metal, that is a metal alloy specially designed to shield magnetic fields. I don't know where you might buy it, though.

http://en2.wikipedia.org/wiki/Mu-metal

I also found some Mu foil (http://www.lessemf.com/mag-shld.html) 16” wide roll, $19 per linear foot.