• 04-07-2006, 07:27 PM
    ThunderousBass
    Please help me troubleshoot hum in Cam. Aud P500
    Got a "new used" Cambridge Audio P500 Power amp and it is exhibiting marked hum. Sounds like a quieter version of the hum a PA system gives off. Volume has no effect on it.

    The device is pretty simple: Left Right Input Output and speaker terminals.

    I think I ruled out screwing up the Input / Output side of things since I only need input from this thing and I also tried it with the Pre-Amp off and it had the same hum.

    I WAS a little confused since CA had the posts labelled in a way I'd never seen before: it was readable from both top and bottom, which makes good sense, since half the time you're hanging over your components -- but again, it's easy once you know how.

    And it actually sounds pretty good otherwise. That is to say, when I pump music through that segment of my system, it's quite nice setting aside the hum.

    Are these units susceptible of noise from the mains? There is rather a lot of junk on that one circuit.

    Any thoughts would be most welcomed. The seller, whom I trust, says there was no audible hum whatsoever.

    Thanks.

    TB
  • 04-08-2006, 07:01 AM
    JohnMichael
    Check to see if you have a ground loop problem. Plug the three prong plug into a two prong cheater plug and once you remove the ground you may remove the hum. Let us know if this helps.
  • 04-08-2006, 07:30 AM
    ThunderousBass
    Thanks very much for your reply.

    I did a lot of diagnostic stuff, like swap out the cables etc., but what worked was simply moving the unit to another outlet. It's quiet as the grave now. :0:

    Quote:
    Originally Posted by JohnMichael
    Check to see if you have a ground loop problem. Plug the three prong plug into a two prong cheater plug and once you remove the ground you may remove the hum. Let us know if this helps.
  • 04-08-2006, 08:48 AM
    JohnMichael
    Quote:
    Originally Posted by ThunderousBass
    Thanks very much for your reply.

    I did a lot of diagnostic stuff, like swap out the cables etc., but what worked was simply moving the unit to another outlet. It's quiet as the grave now. :0:
    I am glad you solved the problem. A different outlet will also help with groundloop hum.