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Thread: Whining/Ground Loop

  1. #1
    Constant Bitrate ZenerDiode's Avatar
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    Whining/Ground Loop

    argh...I'm getting the dreaded alternator whining. I've sanded the grounding area to a bright shiny sparkle, so I'm sure there's proper contact with the car chassis. My amp is definitely grounded well as I get no whining/hissing when I'm in CD or Tuner mode. But as soon as I switch my head unit to Aux-In mode...I hear that ever so faint whine. My amp and my opus are grounded in seperate locations and grounding them at the same spot isn't logistically possible. Would a "grounding distribution block" help? Any other devices to isolate the whine and kill it?

  2. #2
    Maximum Bitrate
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    Measure the resistance at the grounding points. Going by theory, you should only ground devices that have resistance differences of no more than 0.25 ohms to avoid ground loops.

    In theory a grounding distro block would eliminate that, but you said it yourself, it's not possible in your case? i'm guessing they're too far away from each other?
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    Maximum Bitrate Snootch's Avatar
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    Make sure that you didn't accidentally put a screw into an RCA cable, or something like that. You say grounding your amp + Opus isn't possible... Try to connect a wire between them as a test to kill any differences in potential. Interesting article wrote about ground loops:
    http://www.epanorama.net/documents/g...op/basics.html
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    Raw Wave hijinks21's Avatar
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    is everything grounded to the same points? Also try to ground your computer case or motherboard to that same point
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  5. #5
    FLAC
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    THIS got rid of my alternator whine.
    MikeH

  6. #6
    Variable Bitrate
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    and ^^"that"^^ will also cause loss of sound quality. It's a bandage to the problem, not a solution. Best thing is to ground everything to the same point. I don't see how it can't be possible (wires can be bought fatter and longer), but if it is, the resistance explanation above makes a whole lot of sense and is probably a good rule to go by.

  7. #7
    FLAC
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    Bobby,

    I think you may be confusing ^^THAT^^ with THIS , which DOES affect sound quality. The noise filter I referred to is connected to the DC input line to your audio amp and/or CarPC and has no affect on the audio except for filtering incoming noise from the power lines.
    MikeH

  8. #8
    Constant Bitrate ZenerDiode's Avatar
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    thanks for the input guys. actually, I CAN use a distribution block I. I reason I couldn't ground the opus to the same place the amp is grounded is because I put the amp in a while back and basically, that area is inacessible. I mean I could totally tear up the carpet and spend about several hours messing with my seats and their adjustable rails. anyhow, thanks for the info...it'll give me some things to try out this weekedn.

  9. #9
    FLAC chut's Avatar
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    Hey Mike,
    I was going to ask you to recommend something for me. Did you put one on your PC power and one on your Amp power or how specifically did you wire them up?

    Peter



    Quote Originally Posted by MikeH
    THIS got rid of my alternator whine.
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  10. #10
    FLAC
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    Chut,

    Here's what cured my noise problems. It took a nose filter on the +12V line and a ground loop isolator on the RCA auido lines, as well as good grounding techniques.....
    Attached Images Attached Images  
    MikeH

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