Ground loop hum?

Discussion in 'Archived Threads 2001-2004' started by Dave Jewett, Nov 19, 2002.

  1. Dave Jewett

    Dave Jewett Agent

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    Hello all,
    Got a problem with my setup that is getting really annoying. Basically, with no signal I have an audible hum across all of my speakers, sub included. Even with all my sources disconnected (save for the 5 speakers), the hum is still present. My receiver (HK 520) was previously plugged into a power strip with all my other electronics, but moving it to a different plug did not help. I have two lamps on the same circuit but nothing else, and even disconnecting those didn't help. Would it help to have something like this to filter the power: MonsterPower HT800, or could the problem lie with my receiver? Is there anything else I can try? I've got cheater plugs on both the receiver and the sub, but they both use two prong cords, so I'm not sure that will help. Any other suggestions?
    Thanks,
    Dave
     
  2. Dave.....while you have your sources unplugged, answer me this.

    Do you have cable TV and is it hooked up?

    Cable TV can induce some really nasy ground loop hum.
     
  3. Dave Jewett

    Dave Jewett Agent

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    Anthony,

    I do in fact have CATV, hooked up into a splitter between my TV and VCR. I unhooked the connection at the wall, and I still have a hum...

    Thanks,

    Dave
     
  4. Jorge UF

    Jorge UF Stunt Coordinator

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    Try unplugging 1 item at a time from the power strip, with no signals going into the reciever. If the reciever is the only thing plugged into the power strip, and there are no signals plugged into the reciever, then start disconnecting 1 speaker at a time. If you still get the hum, I know that there is a ground loop isolator that can be found at radio shack I believe, that should take away this problem. They can also be found online. I have never used the isolator, but have heard that it works.
     
  5. Chu Gai

    Chu Gai Lead Actor

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    i'm still a bit unclear with this. have you always had this problem or did it recently come up? also rather than unhook the CATV connection at the wall, unhook it from both the TV and the VCR. pls post back with your progress [​IMG]
     
  6. Guy Usher

    Guy Usher Supporting Actor

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    You want to use the 2 prong plugs instead of the 3 prong type, you are getting a 60hz hum from too many grounds. Some times with 2 prong plugs you can turn it over and plug it back in and it will stop the hum.
    Powered subs are the worst for this, many times if they use a 3 prong plug they will supply a 2 prong cheater with it or at least recomend you try that.
    Some times getting rid of a ground loop hum can be tireing_________good luck
    BTW: You may want to ground your power amp's chassis to the chassis of your pre-amp, there should already be provisions on the back panel for that
     
  7. Wayne A. Pflughaupt

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    Dave,

     
  8. Dave Jewett

    Dave Jewett Agent

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    Thanks for all your suggestions... [​IMG]
    I think I've tracked down the problem to the splitter I'm using to attach my VCR and TV to the CATV line. With the splitter removed the hum is still present, but it's not nearly as noticeable. I'd have to be right up next to the speaker or have my sub turned up all the way to hear it. This problem has developed over the last two weeks, when I first set up my HT in May I didn't have any hum at all. Is this slight hum normal?
    Wayne: You are partially correct, my sub is plugged into a different outlet on the same circuit. I moved the sub to my powerstrip but it made no difference.
    Dave
     
  9. Wayne A. Pflughaupt

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