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Plasma TV & RF Interference

Discussion in 'Home Theater Audio' started by jclangston, Dec 18, 2013.

  1. jclangston

    jclangston Cool Member

    143
    9
    Oct 19, 2010
    Does anyone have a fairly high powered power amp near a Plasma TV? I have a Emotiva 200W x 5 channel power amp, the issue I'm having is that I get feedback into my amp from the Plasma TV. Even when the volume is at 0 I get a mild hum through my speakers. If I unplug the Plasma the hum goes away. Has anyone experienced this? I'm not sure if its RF waves traveling through the air or if its back feeding through the wiring in my house. I was thinking about buying a UPS that has a line conditioner built in, but I didn't want to spend the money if it wouldn't help.
     
  2. inkahauts

    inkahauts DIRECTV A-Team

    21,500
    954
    Nov 13, 2006
    Try a line conditioner. That's likely the culprit. A ups with one built in would be nice but you wouldn't want to buy one for your amp just your tv as one that would not hinder your amp would cost a lot of money.
     
  3. kenglish

    kenglish Icon

    973
    2
    Oct 2, 2004
    Salt Lake...
    Do you get the hum when the Plasma TV is plugged in but not turned on?
    Or, just when it's actually running?

    In the first case, that might indicate RFI from the switched-mode power supply....most likely (conducted) via the power wiring or the interconnect cables.
    Some sort of line filter might help, but most don't go down to such low frequencies. If you live in a city, there may be a hospital or a company that services hospital and clinic equipment, that might let you try out an isolation transformer on the power cable. That might help.
    Otherwise, some ferrites that are designed for ham radio and AM broadcast frequencies, could be used on those cables....the more-common ones from places like Radio Shack are designed for VHF frequencies (25-250 MHz), so they won't do it.

    In the second case, it's likely being radiated by the little "arc-generators" in the screen (the actual plasma cells). Moving the amp further away from the TV would help there. try a big piece of metal (like a cookie sheet) as a shield, and see if it makes the noise less noticeable 9as a quick check).

    Here's a ham/audio engineer's guide:
    http://audiosystemsgroup.com/RFI-Ham.pdf
     
  4. gov

    gov Legend

    1,101
    50
    Jan 11, 2013
    And back in the old days, if we had a non-polarized plug in an outlet, we would try it the other way. If more than one piece of equipment, we would try all the permutations.

    If there was a 3 prong plug we might try a 2 prong (GASP!) adapter.

    We could attach or remover the ground wire from the turntable too, LOL.

    And for the really tough cases, one cold always wall paper with aluminum foil.


    :nono2:
     
  5. Rich

    Rich DIRECTV Cutting Edge

    25,596
    435
    Feb 22, 2007
    Piscataway, NJ
    What brand plasma? I have 8 Panny plasmas and have never had that problem.

    Hummmmmmmmmmmmmmmmmmmmmm. :rolling:

    Rich
     

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