Wooo Whooooo! I beat the ground loop hum. Long live the Silence.

Discussion in 'Archived Threads 2001-2004' started by Legairre, Dec 29, 2001.

  1. Legairre

    Legairre Supporting Actor

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    I have two dedicated 20 amp cicuits for my HT gear. One for just the amp and another for everything else.

    Everything was fine until I added the external amp. After adding the amp I had the dreaded ground loop hum. Anyone who has ever had this problem knows that the hum is the most EVIL beast to ever grace a HT.

    Over the past four days I'd been battling the beast one step at a time. To use my amp until I had time to tackle the beast properly. I used a 3 to 2 prong cheater plug(a temporary solution only).

    I started to trace the problem where most ground loop hums come from(DSS or CATV). In my case since I don't have CATV it was my DSS. Disconnecting my DSS coax cable proved that it was the culprit. I checked my DSS and it was bonded to a cold water spigot, I disconnected that and I bonded it to the house ground. This reduced the beast by 50%. To get rid of the other 50%. I grounded the DSS receiver to the amps chassis by running a 14 gauge speaker wire from a screw on the chassis of my DSS receiver to the chassis of the amp(remember that the amp is on a different circuit than the DSS receiver). I spoke with the electrician that put in the amps dedicated circuit and he says that instead of grounding the DSS receiver to the amps chassis. I could have grounded the DSS receiver directly to the dedicated recepticle the amp is plugged into by grounding it to the screws that hold the recepticle in it's box. Either way he says what I did, accomplished the same thing since the amp is plugged into a grounded recepticle it's OK to ground to the amp.

    Now the beast is dead silent unless you put your ear right up against a speaker. From even 6 inches away you can't hear a thing. This I can live with because I'll never be 2-3 inches away from my speakers.

    Sorry for the long note. I hope this helps someone else rid this beast from their HT.

    ooooooooooo whoooooooooooooooooo. The beast is dead. Silence is golden.
     
  2. Kevin. W

    Kevin. W Screenwriter

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    Makes me almost wonder if I should get DSS. Right now my system(Rotel RMB-1066/Marantz AV560U) is static/hiss free. Oh the dilemma.

    Kevin
     
  3. Legairre

    Legairre Supporting Actor

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    Kevin,
    It's a real pain in the ass to track it down and then it's another pain to fix it. I found a product that says it will eliminate all ground loop hums in DSS. The other ground loop isolators won't work because they block the DC current that DSS needs. Here's link to it. I haven't ordered one yet but I'm going to. Heck for $7.00 I'll give it a try. Here's the link. It's called a "63400 Ground Breaker".
    http://www.hometech.com/video/atten.html#dc
    I remember you said I would love my new amp. I had no idea how RIGHT you could have been.
     
  4. Wayne A. Pflughaupt

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    Legairre,

    Just curious, are your dedicated circuits on different legs (at the service panel)?

    Happy Holidays,

    Wayne A. Pflughaupt
     
  5. Lewis Besze

    Lewis Besze Producer

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    I'm not 100% sure but if you'd have pugged the DSS receiver to the same curcuit with the amp,would be still ground loop problem as well? Did you try this?
     
  6. Darren Davis

    Darren Davis Stunt Coordinator

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    Legairre,

    You just fixed one of my HT problems. Since I've never really looked into it I wasn't aware that it was my cable TV causing that hum whenever I'd turn my sub amp on. Well, I just unhooked my cable from the jack on the wall and voila...NO HUM! Ahh, I'm very happy. Even though it's a temporary fix for me I'll just unhook the cable whenever I want to watch a movie. It's in a pretty easy-to-reach location. Thank you very much!
     
  7. Bob_M

    Bob_M Stunt Coordinator

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    Hi All,

    What is the deal with the groud loop? Why does it cause hum and why do the fixes work?

    Thanks Bob
     
  8. Ron Reda

    Ron Reda Cinematographer

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    Legairre,
    Stop rubbing it in, I'm still dealing with my humming. [​IMG]
    I experienced the same problem when I hooked up my new amp. The hun is driving me crazy! It's weird though...mine seems to be coming from my TV. There's only a slight hissing when I put my ear up to the speakers with the TV off (apparently it is normal for tweeters to have a slight hiss). However, once I kick the TV on, the hum is in full effect! I tried one of those Ground Loop Hum Isolators ($7), but like you said, it was designed for cable boxes, so when I hooked it up, it blocked the satellite signal from coming through. I think I'm going to try one from the site you posted. Hey, for another $7, you can't go wrong! I still think I have other electrical issues in my home though. Hopefully, the electrician that's coming out on the 23rd will be able to help...
    Regards,
    Ron
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~
    Bob_M,
    There's PLENTY of threads about the dreaded ground loop hum on this forum...just do a search and you'll see!!!
    Regards,
    Ron
     
  9. John_Bonner

    John_Bonner Supporting Actor

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    Legairre,

    Did you experience any video interference before grounding the DSS receiver?

    The reason I ask is because for the longest time I would get a semi-transparent vertical line that slowly "swept" across my screen when watching DVD's. It would happen when a scene changed from light to dark or dark to light. (I have a Sony WEGA and the DVD is connected via component). Others have posted the same problem. I noticed that if I turned off all other video sources (DSS, Cable box, VCR) the line became "fainter" but if I looked for it I could see it. It became one of those things where once you see it you can't "not" see it, very distracting. Well last weekend I unplugged everything in my setup and went back one by one to find the culprit. It was the DSS receiver. If it was completely unplugged, no vertical line. If it was plugged in but not turned on, a faint line and if it was turned on a visible line. I was going to try a cheap solution of buying an extension cord and plugging the DSS into another outlet (maybe even another room). If that doesn't work I'll try your method of grounding the receiver itself.
     
  10. Legairre

    Legairre Supporting Actor

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    Wayne,
    I'm not sure if the two circuits are on the same leg. I hope they are but they might not be. The electrician says they are but I'll never really know.
    Lewis,
    I did try plugging both the amp and the DSS receiver into the same circuit and the hum was gone.
    Darren,
    Glad I could help. I searched through every thread on hums I could find until I was able to fix my problem. Since you have CATV maybe you should try one of the CATV ground loop isolators at this link. It's only $13.00
    http://www.partsexpress.com/pe/showd...ID=16262&DID=7
    Bob_M,
    Try this link for info on ground loops. It helped me a lot.
    http://www.epanorama.net/documents/g...oop/index.html
    Ron,
    I ordered one of the ground breakers. It should be here on Saturday. I plan on removing the DSS receiver to amp ground and see if it works. I'll post back and let you know if it works.
    John,
    I never had any lines or anything. Just the dreaded humm when I got the amp. If it wasn't for the amp I would have never known that the DSS dish wasn't grounded properly.
     

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