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DIY magnetic Shielding??

Discussion in 'Home Cinema Speakers' started by calibos, Mar 8, 2003.

  1. calibos

    calibos
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    I'm currently refitting the Cinema Room, replacing Receiver, main speakers etc and will be moving the DB930 and Mission 733(Floorstanders 10yrs old) into the living room where the missions will have to go right next to the TV. These speakers aren't magnetically shielded but I found that if I held a biscuit tin lid between the speakers and tv, that the magnetic distortion on the screen disappeared. So my question is what type of metal sheeting do I need and where could I purchase it and have it cut to the right dimensions??

    Also, there doesn't seem to be any way to access the inside of the speaker bar unscrewing the main speaker driver. Has anyone opened up their speakers? Are the internal wires unplugable, ie will I be able to get the driver out of the way without damaging the internal wiring? Ideally I would like to put the shielding on the inside for aesthetic purposes but if this isn't possible I can accept putting it on the outside and painting it black to match the speaker colour.
     
  2. Goverias

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    Hi Calibos,

    Speaker shielding is done internallly for starters. You can buy a cilinder with a contra magnet in it to put over your speakers magnet. When you do this the magnetic field is neutralized. I doesn't help much to put led between your speaker and tv.

    I don't know if you can manage to get your speaker in the same condition after you have opened it up and made the changes because i've never done that.
     
  3. MikeK

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    CPC sell shielding cans for retro fitting to non-shielded speaker drivers.
    Never used them personally though - and I don't know if they contain a bucking magnet or not - probably not I'd guess (these are less than $1 each at partsexpress - don't know of any UK stockists though. You could always butcher an old pair of drivers for the magnets if you had any).

    http://custom1.farnell.com/cpc/prod...pc+catalogue&category_name=&product_id=210330
     
  4. Geoffrey Shrek

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    I bought some lead sheeting from Homebase and wrapped it round my centre speaker. It seemed to do the trick.
     
  5. calibos

    calibos
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    Geoffrey,

    Just the answer I was hoping for. So its lead sheeting I need (even though the biscuit tin/aluminium lid worked as well:D ) There's a Woodies near me, they'd have it wouldn't they?
     
  6. Geoffrey Shrek

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    Biscuit tins are no good. Has to be lead. Superman uses it to shield against kryptonite so it's the best stuff to use.
     
  7. porker

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    Do not bother buying lead, it is completely crap at magnetic shielding.
    Magnetic fields cannot actually be blocked, there is no such thing as a magnetic insulator, magnetic field lines MUST terminate at the opposite pole.
    The way "shielding" works is by re-routing magnetic field lines to the opposite pole, so the material used to do this has to have high magnetic permeability.

    Crap shielding material with low permeability would be things like lead, copper, aluminium, tin, air.

    Good material to use iron, stainless steel, nickel.

    So your (steel) biscuit tin would probably work fine:smashin:

    Keep the lead for hiding Kryptonite:D
     

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