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Alternator Whine in Speakers

Discussion in 'Audio' started by schlechto, Oct 5, 2001.

  1. schlechto

    schlechto Registered Member

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    I just installed an amp in my Jimmy but when I take to the streets I get an awful alternator whine in my subs. I have a good ground to the frame and I have tried to do what the amp manufacturer said but I don't understand it. The noise goes away when I unplug the RCAs but the manual doesn't say what to do after that. Your help will be greatly appreciated.
     
  2. Pugsley

    Pugsley 1/2 ton status

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    Make sure your head unit has it's own good ground, and that your RCA's are ran away from the amp's power cable. If that doesn't cure it, you need to pick up a "ground loop isolator" - it plugs inline with the RCAs and clears out the whine. Just about any decent shop, or even Radio Shack should have them for around $15-$20 bucks.

    Of the 5 toughest dogs in the neighborhood, my cat's ranked #3
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  3. flblazer

    flblazer 1/2 ton status

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    call a amp shop an ask them for a amp noisefilter i just got done wierin my amps up 1 is my subs its 900 wats briged 2 oms an my small amp makes the but i can live with it hope this works for you like its workin 4 me

    can some 1 find me a ford i need to take a pee still peein on that ford just have to keep goin dam i can not stop pissin:) k5s kings
     
  4. schlechto

    schlechto Registered Member

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    I tried what you guys said but with no luck. I will have to check out the gadgets that you both mentioned.
     
  5. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Don't panic quite yet.....try grounding the deck to the same point as the power amp (the frame ground) even if it's just with a temporary wire and see if that helps. You definitely have a "ground loop" the question is how bad it is....

    You have already done some good troubleshooting. The fact that the RCAs being unplugged gets rid of the noise means the problem is in the deck, so it's either a bad ground (which you will check with the test mentioned above) or the deck has poor power supply isolation to begin with. It is possible to add a high quality isolated power supply to the head unit you have, but unless the deck is REALLY expensive or you have some other reason that you MUST keep that deck, you'd be better off buying a better quality unit to replace it.

    Not to diminish anyone else's suggestions, but the use of "line filters" is a poor choice to solve this problem. They are of inherently poor quality and while they might remove the alternator whine, they will also kill your dynamics and overall signal quality. IMHO it's always better to address the "source" of the problem than to try to band-aid it with those types of devices.

    Good Luck and let us know how the experiment works!

    -Greg72
     
  6. schlechto

    schlechto Registered Member

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    Ok I'll try addding a new ground. I just bought this deck too it is a really nice pioneer and cost me $190. I will update you all tomorrow.
     
  7. Pugsley

    Pugsley 1/2 ton status

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    Pioneer's usually have a really good power supply, so it's definitely a grounding issue. If running a jumper to a frame ground doesn't kill it, try disconnecting the antenna lead and see what happens. Some head units try to ground through both the antenna and ground wire. If pulling the antenna plug kills the whine, trace the antenna cable back and see if there's an abrasion in the insulation anywhere, causing it to pick up the RFI from the alternator. Also try running a short jumper from the head unit's chassis to the dash or firewall.

    Of the 5 toughest dogs in the neighborhood, my cat's ranked #3
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  8. Ddragggon

    Ddragggon 1/2 ton status

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    another good one to check, is that your engine ground strap is connected. connecting mine on my suburban made a world of difference. you might also try running a heavy ground from the battery to the frame, in addition to the heavy one from the battery to the alternator bracket. if you can, try and get a differnet piece of RCA cabling to run to the Amp, or try running a somewhat short `1/8" phone plug to Stereo RCA' cable, and plug a portible CD player directly into it. also, it might do to check the amp power on signal cable, and make sure its clean, and abrasion free.

    Good luck with it,
    -Rich

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