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ground loop isolator

Discussion in 'Home Cinema Speakers' started by dazed&confused, Mar 24, 2005.

  1. dazed&confused

    dazed&confused
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    I have what appears to be a common problem, which is a humming subwoofer in my home cinema system. After perusal of all the threads I can see it seems it's because of a 'ground loop'.

    I've tried the obvious things without success and can't even fathom some of the things people are talking about. Some are just too technical for me. Other things, like looking to see if my sub has an earth wire in the mains lead, can't be done becaue it is a sealed plug (or am I just beimng thick?).

    The simplest solution, then, seems to buy a 'ground loop isolator' but I have two questions.

    1) Where do I actually stick the isolator? Between what and what? I've seen pictures of two isolatore from links on here and they both have two phono leads.

    2) Is the device likely to deteriorate sound quality in any way, for example by filtering out some frequencies?

    By the way, my sub is a Castle Cube.

    Thanks.
     
  2. dazed&confused

    dazed&confused
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    Does no replies mean the quesions are just too dumb or nobody knows the answers?

    Thanks
     
  3. wookie

    wookie
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    The GLI goes between the sub and the receiver.
    Keep it away from mains cables!!

    Have you tried connecting the back of your receiver to the back of the subwoofers metal panel?
    Run a cable between the two of them and the hum should go away!

    Does your sub hum if it has nothing plugged into its inputs?

    If it does hum without an input conection (No ground loop), it could be faulty or poor house wiring somewhere.

    Try powering the sub and receiver from the same outlet.


    hth'S
     
  4. dazed&confused

    dazed&confused
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    Thanks for the reply.

    I'm not sure that my sub does have a metal panel. It does have a panel of some sort but I'm not sure what it is made of. I have tried a cable from the 'ground' connection on the back of the amp (usually used for turntables I believe) to the panel and on the sub, and to the heat sink on the sub and it makes no difference to the humming.

    The sub does not hum at all if there is no input to it from the amp.

    I have the sub in the middle of the room, away from any cables.

    The hum is reduced a lot, but not completely, if I remove the phono leads from stereo out on the TV to the amplifier.



    To return to the ground loop isolator, if it goes between the amp and the sub then why does it have two phono leads? And wouldn't putting it between the amp and the sub deteriorate the audio signal to some extent?

    Thanks.
     
  5. Harry T2

    Harry T2
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    Hi Dazed.

    The humm is reduced when the TV is connected. This leads me to believe that the arial or dish is not grounded properly.

    Don't know anything about the isolator, but perhaps a call to an electrician is needed.
     
  6. dazed&confused

    dazed&confused
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    Thanks for the reply Harry.

    But no, the hum is reduced when the TV is NOT connected to the amp, not when it is connected.
     
  7. Harry T2

    Harry T2
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    Sorry D&C.

    My bad typing. I meant to say when the TV is NOT connected. I still think the aerial or dish isn't ground properly.
     
  8. dazed&confused

    dazed&confused
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    Thanks Harry.

    I've tried unplugging the ariel from the TV as well and it makes no difference to the hum. Does this suggest that the problem isn't with the quality of the ariel ground?
     
  9. Harry T2

    Harry T2
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    It would be highly unlikely to be the culprit then.
     
  10. jookster

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    2 suggestions,

    firstly try different plug sockets for basically anything connected
    try pulling out phono sockets so the earth is not connected, it could make it worse - rfi interference for example or cut out the hum.
     

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