Ground-loop and satellite...How to fix?

Discussion in 'Archived Threads 2001-2004' started by Levesque, Sep 30, 2002.

  1. Levesque

    Levesque Supporting Actor

    Joined:
    Mar 21, 2002
    Messages:
    586
    Likes Received:
    0
    Trophy Points:
    0
    I got an awful hiss coming from my amp when my coaxial feed is hook to my sat decoder. When I unplug this coaxail cable, perfect silence. I plug it, then I can hear the hiss from 10 feet!! I have redone all the grounding of the house, and got a dedicated 20A circuit installed. Everything pass trough a Monster HTS-2500. I have tried to link all the chassis from the pre-amp, amp and sat decoder togethers with copper cables. RF-isolator from Rat Shack doesn't work. Nothing works.

    I just receive this answer from Jensen about the ground-loop isolators they sell:

    "Unfortunately, you cannot use a capacitive (VRD-1FF) or transformer (VR-1FF) type isolator on your satellite cable feed. Both types of isolators will interrupt the DC power to the satellite dish and prevent it from operating. You are going to need to isolate the outputs of your satellite dish receiver box instead. We manufacture isolation units for all of the different outputs that your box might have.
    Dale Roche - Project Engineer"... Great...

    My sat installer tell me that "to much signals coming trough the dish"...?!?! What does this is suppose to mean??

    So what I am suppose to do know??? Someone here was able to solve that kind of loop with a sat dish??
     
  2. Lee Petty

    Lee Petty Stunt Coordinator

    Joined:
    Jun 1, 2002
    Messages:
    204
    Likes Received:
    0
    Trophy Points:
    0
    i have heard that you can take a 75ohm to 300ohm adapter (the kind that takes a f-connector and turns it into spades) and hook it to a 300ohm to 75ohm adapter (where you can hook up the spade type connection to a f-connector) and it takes out a ground loop. just hook your coax to the appropriate ends.
     
  3. Levesque

    Levesque Supporting Actor

    Joined:
    Mar 21, 2002
    Messages:
    586
    Likes Received:
    0
    Trophy Points:
    0
  4. Alex F.

    Alex F. Second Unit

    Joined:
    Aug 29, 1999
    Messages:
    377
    Likes Received:
    0
    Trophy Points:
    0
    I'm new to DSS (DirecTV) myself. An MIT Cable rep just happened to mention to me last month that a Toslink cable will break a satellite feed's audio ground loop, a benefit of the nature of fiber optics. If your satellite receiver has a Toslink output and you do indeed have a ground-loop problem, it may be the solution you seek.

    Good luck!

    PS: When I had a cable-TV ground-loop problem several years ago, it caused a loud hum, not a hiss. I'm not so sure ground loops can create hiss. Anybody...?
     
  5. Levesque

    Levesque Supporting Actor

    Joined:
    Mar 21, 2002
    Messages:
    586
    Likes Received:
    0
    Trophy Points:
    0
    Update. Sat technician (Star Choice) just came by. Got the usual "first time we see something like this...but it's the first time we see a system like yours!" (I think it was a compliment)[​IMG] .
    The dude was here 2 hours. We tried everything. We can hear the sound from 10 feets!! He said everything is perfect, grounding, etc. So he will do some research and give me some news this week. Really nice guy. But I had to fill a complaint to the CRTC of Canada to make them move.
    He told me that ground-loop problems are fairly common, but they usually cause problems with the picture...
     
  6. Wayne A. Pflughaupt

    Moderator

    Joined:
    Aug 5, 1999
    Messages:
    6,207
    Likes Received:
    56
    Trophy Points:
    9,110
    Location:
    Katy, TX
    Real Name:
    Wayne
    Lévesque,

    Alex is right, a ground loop problem is shown as a hum or buzz, not a hiss. A hiss indicates a problem with your electronics. Either the input in your receiver that the DSS is plugged into has a problem, or your DSS receiver itself has a problem.

    Regards,
    Wayne A. Pflughaupt
     
  7. Levesque

    Levesque Supporting Actor

    Joined:
    Mar 21, 2002
    Messages:
    586
    Likes Received:
    0
    Trophy Points:
    0
    I don't really know if it's a hiss or a hum, because it's coming from the tweeters, mid and woofers!! And I can hear it at the listening place at 10 feets! With the dish technician, we tried 3 different decoders and the sound was always there (so not a bad decoder). If I unplug the decoder I'm in silence nirvana. When any connection is done to the decoder (S-VHS, RCA, Component video, digital, DVi) then the sounds start. We have try to unground everything, no use, sound still the same.

    To listen to a DVD, I have to unplug the coax from the sat decoder. It's really annoying.
     
  8. Jeffrey Chin

    Jeffrey Chin Second Unit

    Joined:
    May 22, 2001
    Messages:
    483
    Likes Received:
    0
    Trophy Points:
    0
    i witnessed the exact same problem, except i have comcast digital cable. i have it connected to my replaytv as well. save yourself time and headache by buying one of these babies. problem solved.
    3 words:
    MONDIAL MAGIC BOX
    http://www.audioadvisor.com/store/p...20TV%20Isolator
     
  9. Levesque

    Levesque Supporting Actor

    Joined:
    Mar 21, 2002
    Messages:
    586
    Likes Received:
    0
    Trophy Points:
    0
    Jeffrey. Thanx for the info, but if you look, down the page, in little caracters, the omnipresent and usual:

    Please note: this unit is not compatible with DBS satellite systems.

    Tada!
     
  10. Bob McElfresh

    Bob McElfresh Producer

    Joined:
    May 22, 1999
    Messages:
    5,182
    Likes Received:
    0
    Trophy Points:
    0
    Dumb question: but is your DSS dish grounded? There is a separate wire that is typically run to a water pipe/earth ground that might bleed off noise picked up by your dish.

    Second: Disconnect your CATV feed (if you have one). This can often contaminate the signal-ground of your electronics. Also, try disconnecting all inputs to your receiver except the DSS feed. One of these cables may be injecting noise that you hear on the DSS source.

    Third: Have you always used the original coax from the dish to the receiver? This could be running near a power wire or picking up some noise. See if the tech will run some coax hanging loose and going through a window to your receiver to simply try a separate path and a different coax cable.
     
  11. Drew Eckhardt

    Drew Eckhardt Stunt Coordinator

    Joined:
    May 10, 2001
    Messages:
    246
    Likes Received:
    0
    Trophy Points:
    0
    Ground loops result in a 60Hz hum, while you have white noise.

    I'd suspect a problem with the satellite receiver's analog outputs; the corresponding input on the preamp/receiver; or the wiring.
     
  12. Levesque

    Levesque Supporting Actor

    Joined:
    Mar 21, 2002
    Messages:
    586
    Likes Received:
    0
    Trophy Points:
    0
    Thanx Drew. But that's not that easy to find the problem, and there is a lot of things to do and check.

    Maybe I should try what Jensen is suggesting, and isolating all the inputs on the sat decoder?

    Problem is I already did check all those things you suggest. I've tried all the analog input on the pre-amp with hooking another component...everything ok there, silence heaven. I've tried changing all the interconnects, same noise, same problem. I've tried 2 different sat decoder, same problem again.

    So input on the pre-amp are ok, wiring is ok, sat decoder ok...I'm stuck...
     
  13. Levesque

    Levesque Supporting Actor

    Joined:
    Mar 21, 2002
    Messages:
    586
    Likes Received:
    0
    Trophy Points:
    0
    Didn't see your post Bob. The grounding was done by one of my friend electrician. The Sat tech told me that the job was really well done, everything at the good place, with better cables then they usually use. The dish is grounded, and the coax is too. We have tried ungrounding everything w/o results. The guy is sure that the ground is not causing the problem.

    The coax idea is a good one. I will try running a different cable outside the walls, directly from the dish to the sat decoder, to see if it could be this. When they have done the ceiling in the basement, there was a lot of electrical wirings there, and they didn't wait for me to close it... So I will cross my fingers and try it tomorrow...
     
  14. BobRoulier

    BobRoulier Second Unit

    Joined:
    Mar 16, 2002
    Messages:
    347
    Likes Received:
    0
    Trophy Points:
    0
    I briefly had a rotel 1095 and now a parasound 2205 in my rack and I had a serious hum from the speakers I found my problem to come from the cable tv coax my dealer told me to use a cheater plug from the amp power cord to the power outlet and it worked hum completely gone! I know that is not the best thing to do but it will have to do until I get power conditioner which should take care of the problem[​IMG]
    Bob
     
  15. Claude M

    Claude M Stunt Coordinator

    Joined:
    Jan 18, 2001
    Messages:
    239
    Likes Received:
    0
    Trophy Points:
    0
    hold on to your hats, the cheater plug has been mentioned!
     
  16. Levesque

    Levesque Supporting Actor

    Joined:
    Mar 21, 2002
    Messages:
    586
    Likes Received:
    0
    Trophy Points:
    0
    I just tried a cheatet plug... It's not working, so it's not a ground-loop. I'm really disappointed with this journey to the separate world. Since I add my amp to my system, it's getting worst and worst.

    The Sat company don't know what to do to help me "first time we see this". Rotel dealer tell me it's the sat, Yammie dealer tell me it's the Rotel...

    When the sat decoder is not plugged in the outlet, I still got this sound!! So when the dish coax feed is in the decoder, I'm in hell. I've tried disconnecting all the outputs of the decoder, one-by-one, and if any of the RCA, S-VHS, digital coax or component is still in, I got this crazy sound. I've tried in all the different input behind the Yammie with same result. I've change the Sat decoder 3 times.

    I really don't know what to do anymore. I'm figthing with this since 1 month now.

    I think I will have to just unplug the sat each time I listen to music or a DVD. Really stupid, but the only thing working.
     
  17. Bill_Jackson

    Bill_Jackson Auditioning

    Joined:
    Oct 28, 2002
    Messages:
    6
    Likes Received:
    0
    Trophy Points:
    0
    switching from digital coax to optical eliminated the hum from my system.
     
  18. Levesque

    Levesque Supporting Actor

    Joined:
    Mar 21, 2002
    Messages:
    586
    Likes Received:
    0
    Trophy Points:
    0
    Bill, I finally found my problem. I switch my pre-amp from a Yammie RXV3200 to a Rotel RSP-1066, and abracadabra, perfect silence. It was probably a matter or internal grounding of the different components plug together. But, problem solve for me[​IMG]
     

Share This Page