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Mains Hum

Discussion in 'Cables & Switches' started by cR4cKF0x 5TevE, May 16, 2005.

  1. cR4cKF0x 5TevE

    cR4cKF0x 5TevE
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    Help, my system has suddenly developed a mains hum: I noticed this at the weekend.

    Over the last week I have changed the mains cables to my receiver, Sky + Box, and LCD tv, as well as the mains cable to my sub. My sub cable is now plugged into a different mains block from the rest of my components: this is the only 'positional' change to the leads going into the components. I removed the high level sub connection last night which reduced the sum markedly but it is still there in the background. I have read somewhere that the sub and the receiver should be plugged into the same mains block such that they share the same earth: this would make some sense and could explain why this problem has suddenly materialised.

    Any thoughts anyone? :lease:
     
  2. matblack

    matblack
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    You have introduced a difference between the two earths, I did this and it was truly horrible :(

    What I did was run a small piece of bell wire from a metal point on the sub (stuck it under a screw on the controls plate and screwed it down) then run this back to the amp and do the same thing (just under a chassis screw).

    Killed the issue outright :)

    MB
     
  3. cR4cKF0x 5TevE

    cR4cKF0x 5TevE
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    Thanks for that: sounds simple(ish). Alternatively, I guess I could try moving the subwoofer mains leads back to the same mains block as the receiver: would that help?

    In addition, my old mains lead supplieds with the receiver and subwoofer didn't appear to have an earth connector, whereas my replacement leads do: would this be the source of a potential problem as well?

    Its annoying when these things suddenly surface isn't it?
     
  4. cR4cKF0x 5TevE

    cR4cKF0x 5TevE
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    Matblack

    Thanks mate: I think you were right with the 'split earth' theory. Have plugged the subwoofer lead into the mains block with the rest of the components and hey presto: hum has gone!

    Pproblem is I now have a 1m Black Rhodium Super Mains 25 lead surplus to requirements (had to go back to the original mains lead supplied with the sub). Looks like the classifieds for me tonight.
     

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