Video Shielding

We had a problem with out monitor at work with it backing up to speakers in the next rooms wall and we took some old VCR housing bottoms and screwed them to the wall behind the speakers and it worked. You cannot allow the magnet of the speaker to hit the metal or it won't work. You might have to play with placement some too. Even though the plates had small ventilation holes in them it still worked (it didn't need to be a solid sheet).

Jim

Using sheet steel and/or iron sheets between your monitor and speakers will deflect the magnetic field. The thicker hte sheets the more effective the material will be at shielding. If you don't mind doing a bit of extra labor, you can use two thinner sheets of steel and give them about a 1/8" gap between the sheets. The sheet closer to the subs will deflect the magnetic field and the second sheet will compress the resulting field further shielding it.

(Science Warning; nothing practical for use)
Now if you want to stop the magnetic field all together, use a superconductor (0 resistance iron). Magnetic fields can't get through it.

Extreme1 also brought up a good point. What type of screen is it ?.

As far as mu-metal/Schmu-metal and luck, heres another lucky experiment I just did using a triangle shaped magnet used in fabrication of tube chassis and for body work and a plain old piece of sheet steel bought at the local hardware store. The magnet was so close to the metal plate that it stuck to it. 

https://rides.webshots.com/photo/2857743330049730488dbiOsF

Jim

DYohn] wrote:

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heet steel does not really work unless you get very lucky.  You have to use special magnetic shielding material called "mu metal."  It is available by rather expensive.  A much easier option is to purchase the proper bucking magnets for your subs and epoxy them to the backs of the speaker magnet structures.

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For example, here is a magnet without any shielding or whatever.
The two poles are free to let their fields spread normally.

Using a superconductor of some sort, the field is fully repelled.
It's the basis for experimental friction-free magetos and motors.
It's also very exspensive to maintain and purchase.

Now sheet steel contains iron which helps to absorb and deflect magnetic waves.
Being that it is an alloy, it's not perfect but it is a heck of a lot cheaper than superconductors or
sheet steel treated with molybdenum (which is where you pay the price).
This image is how a piece of sheet steel will react around a magnet.

The second sheet of sheet steel I mentioned takes the stray magnetic waves
and deflects them further out to better shield the compenent.
Again not perfect, but more than enough to take care of MOSt subwoofer fields.

With most subs, the field is already distorted deeper into the subwoofer via the
magnet structure's pole and top plate. So radiated magnetic fields are already reduced.

Now mj239air didn't say if the television is LCD, CRT, or plasma.

If it is an LCD, then shielding isn't required, but recommended (just one sheet) at least on the back side of it. Get the sides covered too if you can.

CRT's WILL need shielding for it, the electron guns inside it work by making their own magnetic field that makes the electrons go to the appropriate location on the phosphorus (screen).

Plasmas will need shielding just on their backsides. Most are usually already built with some shielding in it but the shielding tends to get thin on the back of them. The kickback for the plasma though is that they become susceptable to elevation changes, particularly above 8,000 ft. The thinner air has been known (and recorded) to pop the filaments in the screen. This isn't as big an issue in top series of many brand names (such as pioneer elite [drools] and mitsubishi's PD series of plasmas) but lower valued plasmas tend to be vulnerable to this flaw.

If any of the signal wires for the video runs within 18" of the subs, then recommend getting them shielded, or better yet, rerouted around the subs and their fields. If you ahve to shield, using braided line covers made of steel will work beautifully and give the wiring a trick look to it.

mj239air wrote:

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It is a 20" LCD, so from reading replies it looks as though I can get by with just one sheet of metal to prevent anything. Thank you all for the help, I will definitely let you know if it all works out!!

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extreme1 wrote:

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mj239air wrote:

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It is a 20" LCD, so from reading replies it looks as though I can get by with just one sheet of metal to prevent anything. Thank you all for the help, I will definitely let you know if it all works out!!

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you don't need any shielding, LCD is not affected by magnestic fields

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Ya man, after reading the first post in this thread I was scratching my head, asking my self why this was even being asked.

      This forum is SO OUT OF PHASE with the car audio one    there you ask a ? and 20 people give their 2 cents and the ? is never answered    here you can get the right answer and get it again and again.

        Good work  Extreme!!!!!!!