The dreaded HUM...Please Help!!!

Discussion in 'Archived Threads 2001-2004' started by NickSP, Oct 24, 2002.

  1. NickSP

    NickSP Supporting Actor

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    I am getting this strange low level hum from my speakers and am able to narrow it down to it being as some kind of noise from A/C lines or something. These are the things I've tried.
    1) Made sure the grounding was OK
    2) Made sure the inter-connects were snug
    3) Tried cheater plugs
    4) And everything else.
    Now I know this is not the fault of either my amplifier or prepro as I hooked up my 2802 as a prepro and the hum was much more significant. I also tried my friend's NAD amplifier but with same results.I also get this hum from my TV speakers.
    Is there anything reasonable priced out there that will sove my problem? Any ideas or theories? Although the hum is not that noticable during daytime, it gets very obvious at night. HELP!![​IMG]
     
  2. Gary_R

    Gary_R Agent

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    Are you using a cable TV line in your HT? (Not sure if this falls under "everything else.")

    Gary
     
  3. NickSP

    NickSP Supporting Actor

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    No I am not. I have Dish network and I unplugged the dish receiver completely and still the hum exists.
     
  4. Bill Kane

    Bill Kane Screenwriter

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    Nick,
    You say you've checked to "make sure the grounding was ok" but there can be dozens of paths for mismatches and ground loops. It can be a MAJOR task to track them down, which actually is the preferred method -- go to the root.
    The quick 'n dirty responses usually heard are:
    * Check for bad grounding on a CATV or DSS cable.
    * Use a cheater plug.
    * Install a dedicated circuit.
    * Buy a Balanced Power or Isolation Transformer power conditioner to eliminated electrical line noise.
    Maybe some of these "fixes" might work, but also they may just mask your root problem. The uneviable task becomes to find the problem, and it may take disassembling entire system, sigh, if your “problem” is that objectionable.
    Here is an archived thread which covers some of this; two of the posters, BruceK and Wayne Plughaupt, are among the best “electrical/wire guys” in HTF. Give you something to chew on.
    bill
     
  5. Shawn McBride

    Shawn McBride Stunt Coordinator

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    Are you using a power strip? If so, check that. I had a low level hum induced by my no-name power strip. I found that the loudness changed with the relative position and orientation of the power strip to my reciever or amplifier. I purchased a $50 TrippLite Isobar and the problem went away. It should be a quick check to rule that in or out.

    Shawn
     
  6. NickSP

    NickSP Supporting Actor

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    Bill,
    Thanks for the link as it made very interesting reading. I should try the Automotive isolators. Any ideas where I can get them?
    Shawn,
    I am using a $30 power bar but I will try without the power bar first to see what results I get. Thanks.
     
  7. Lee-c

    Lee-c Second Unit

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  8. Bill Kane

    Bill Kane Screenwriter

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    Nick doesnt say he has cabletv, so that's out. He has DSS but unplugged it doesnt affect his speaker hum.
    It's interesting that the freestanding tv speakers emit hum too, right? Suggests AC lines. Cant figure daytime vs night time levels of hum, unless the house wiring load is higher when everyone is at home.
    What's changed in your system? Components been swapped in/out? Have you always had a speaker hum but only now want to attack it? I can appreciate looking for a $10 isolator over a $999 Balanced Power Technologies box.
    A more robust surge/power conditioner might take out some AC line noise from RFI/EMI. You'd probably benefit anyway from a nice Panamax MAX8 DBS+5 here for ~$75.
    You checked that interconnects are snug – perhaps a termination on one has become loose, breaking a ground.
    Are the HT components including a sub plugged into two different house circuits? If so, have you tried plugging everything into one circuit? Are there any other household appliances using the HT circuit (a no-no).
    Is the master household main service electrical ground secure? Sometimes if there’s a ground rod outside the service box the clamp gets corroded and becomes loosened. Worth a check.
    bill
     
  9. Chu Gai

    Chu Gai Lead Actor

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    you said the dish network is unplugged. does that mean that there's no connection whatsoever to your unit?
     
  10. NickSP

    NickSP Supporting Actor

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    Chu, I am not even plugging the Dish receiver in. It is completely unplugged and so is the TV. When I plug the TV in, I get a similar hum frm the TV speakers too.
     

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