Center Channel Distorts TV Picture

Discussion in 'Archived Threads 2001-2004' started by Gregg W, Dec 24, 2001.

  1. Gregg W

    Gregg W Auditioning

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    i have an il36 infinity center channel. when i place it ontop of my tv, the picture distorts and changes colors. does this mean the speaker is not properly shielded and is deffective? any suggestions/comments are appreciated.
     
  2. Carl Johnson

    Carl Johnson Cinematographer
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    If the speaker is distorting the picture on your television then it is not properly shielded. You should immediately move it to a safe distance or the TV will be damaged. If the speaker is advertised as being shielded then it is defective.
     
  3. Mike boettner

    Mike boettner Stunt Coordinator

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    take it back, get a new one.
     
  4. Gregg W

    Gregg W Auditioning

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    thanks. i'm going to take it back.
     
  5. Kevin C Brown

    Kevin C Brown Producer

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    I have a "stupid question" here:
    If something isn't shielded, but needs to be, you just wrap a conductor around it and attach to ground?
    I was thinking that maybe wrapping your speaker in Al foil might work, but I just don't know! [​IMG]
    And of course, if it is *supposed* to be shielded by the manufacturer, sounds like they missed one...
     
  6. Jake T

    Jake T Stunt Coordinator

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    No shielding. Get real speakers.
     
  7. Jake T

    Jake T Stunt Coordinator

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  8. Jake T

    Jake T Stunt Coordinator

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    Aluminum Fouil???????????????????????????????????

    WHAT??????????????
     
  9. Allan Jayne

    Allan Jayne Cinematographer

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    You are probably better off keeping a distance between that speaker system and the TV picture tube.
    As far as aluminum foil goes, we need to distinguish between shielding from speaker magnets (like direct current) and shielding from power cables or nearby video cables (like alternating current).
    I don't know how to design tghe different arrangements of shielding to fix these problems, sheet aluminum and sheet steel is sometimes used but needs to have the proper shape and dimensions.
    Video cables and often audio cables too are shielded by wrapping with foil or braid (that is what coax cable is). The problem here is that the impedance of the cable varies with the shielding hence the need for proper design to maintain the desired 75 ohms. I doubt if putting a sheet of foil under the speaker where it rests on the TV cabinet will work, or even if wrapping the entire speaker cabinet with foil. I believe that speaker magnetic shielding consists of several layers of metal separated by layers of plastic to maintain the proper spacing.
    Video hints:
    http://members.aol.com/ajaynejr/video.htm
     
  10. Jay Mitchosky

    Jay Mitchosky Producer

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    Jake

    Three replies in a row, and not one of them offering anything positive to the discussion.
     
  11. Kevin C Brown

    Kevin C Brown Producer

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    Yeah, I was thinking of that sheet Al as being more effective than Al foil anyway.
    The reason I ask:
    (I told you this was "stupid"...)
    I remember a TV show or something where the dude was complaining about all the EM interference in a typical apt in a big city. So to combat it, he lined all the walls of his apt with Al foil.
    I just wondered if it would actually work.
    Something to do when I get old and want to "freak out" the relatives... [​IMG]
     
  12. Allan Jayne

    Allan Jayne Cinematographer

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    Lining the room with aluminum foil weakens, as seen from the room interior, the already weak radio frequency energy coming from the outside, energy that doesn't cause problems unless it enters the preamp stages of amps and video equipment and RF stages of radios.

    The magnetic field from the loudspeaker is too strong for one layer of foil. Instead the shielding is intended to re-shape the swirly pattern of the magnetic field so it doesn't pass through the TV picture tube or other sensitive nearby objects.

    Shielding to significantly block nearby strong magnetic or electromagnetic fields is heavy and expensive, and usually contains steel in addition to or instead of aluminum.
     
  13. ScottAndrew

    ScottAndrew Stunt Coordinator

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    So would this mean that placing my subwoofer under my television is a really bad idea? I had wondered about that because my bass is slightly localized to the right where the subwoofer sits, so I thought I should at least center it under the TV. Or is there something I can put under the table to shield it? It would leave about 8 inches from the top of the subwoofer to the bottom of the TV.

    Thanks
     
  14. Gregg W

    Gregg W Auditioning

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    jake, please elaborate, what do you mean by " no shielding, get real speakers"? do you have knowledge that infinity generally doesn't shield their speakers very well?
     
  15. Phil

    Phil Stunt Coordinator

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    Gregg W,

    I have the exact Infinity Center Channel(Il36) and have had no problem with its shielding. Definetly exchange it for a new one.

    Phil
     
  16. Rhys Frost

    Rhys Frost Auditioning

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    Hi guys,

    what about the shielding around the TV? If the TV is old it's possible it is the problem and not the speakers. Just a thought.
     

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