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Earthing Loop Problem & Resolutions!!!

Discussion in 'Home Cinema Speakers' started by WBC, Dec 5, 2002.

  1. WBC

    WBC
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    Guys,

    As mentioned on a previous post I have what looks like an earthing problem on my sub.

    I have searched the forums for posts on 'earthing loop' problems and was quite overwhelmed with the amount of problems this has caused people.

    After reading the posts, I'm just as confused as when I started :blush: !!!

    Is there anyone out there that can give a definitive list of options to try to resolve the problem or is there a way we can collate all of the relevant info into one post.

    Heres Hoping ;)
    Stace
     
  2. Timmy B

    Timmy B
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    Aye, any input would be great!
     
  3. MikeK

    MikeK
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    Assuming that you cannot eliminate the problem on the supply side, then there are several things I know of that you can try (there may be more) Bear in mind though that buzzing from the subwoofer is fairly common, and often isn't a ground loop problem at all (it's often a design issue in the subwoofer amp's power supply).
    To check it is a ground loop problem (or is likely to be), just disconnect the phono lead from the sub - if it still buzzes, it isn't a ground loop problem.
    If the buzzing stops, and then starts again as soon as you reconnect the phono, then it may well be a ground loop problem.
    (if you are connected via high level connections, you'd need to remove those also).
    Also, bear in mind that you can still have ground loop issues even if neither unit has a mains earth connection.


    Things to try -

    Connect the subwoofer to the mains at the same point as the AV amp.

    Disconnect the outer shield of the phono lead at one end only (usually the sub end - but IMO this is just convention, I don't think it really matters which end)
    This is probably the easiest and most effective solution - it may increase the cables susceptibility to EMI/RF a touch, but that shouldn't be an issue in practice.

    Use a "ground loop eliminator"/ audio transformer.


    One thing I wouldn't do is just disconnect the mains earth to the sub, if it uses one - it's potentially unsafe, even if it may cure the buzzing.
     
  4. WBC

    WBC
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    Thanks for the replies.

    How do I remove the outer shield from the phono lead. Might be plain obvious by looking at it (I haven't yet!) but better safe than sorry.

    I have a concrete floor that has been channeled out to take the phono IXOS lead and then covered with soundproofing and wooden flooring. If I mess up I'm F****d!!!!! :clown:

    Stace
     
  5. BK Electronics

    BK Electronics
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    Another common problem with hum is that most equipment these days is double insulated which means there is no need to earth the equipment. The result is that everything is floating and picks up hum.

    A trick to try is to wire a lead into the earth pin only of a 3 pin plug, plug this into a socket switched off for safety, then touch the wire on the outside of your metal phono case. This may or may not work, but is quite simple and worth a try.
     
  6. WBC

    WBC
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    Any More for Any More??? :) ???
     

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