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Thread: HU Gnd upgrade? hiss issue

  
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    HU Gnd upgrade? hiss issue

    I've just installed a new system (2 amps,components 2x subs) and I'm suffering an awful hiss from the Blaupunkt head unit (Hamburg MP68 ),I've swapped the audio source to the amps (MP3 player plugged in directly) and no hiss, so I'm pretty convinced its the HU causing the problem ,loop Isolator makes no difference, I've tried different driver's,different RCA's, running the RCA's direct to the amps directly through the car seperate from all the other power cables and It's still there,as soon as you turn the volume on the HU up to 1 the hiss is apparent untill you get loud enought to drown it out,however it gets no louder.

    Im left thinking its the ground for the head unit thats the problem (in the car loom) ,how do I go about checking this and fixing it if that turns out to be the issue.

    I have searched this a few times so if I have missed the explanation could someone point me in the right direction please, as I've just spent about a grand on this bloody system and this is driving me nuts...

    Thanks

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    Welcome mate

    I have had this problem and it was fixed 95% by taking the powers for the headunit from the battery, even the accessory through a relay

    You could do the same with the earth if you feel thats the problem
    Want a professional job done on fitting your aftermarket electrical accessories? PM me for a quote
    Electrical fault finding also taken on
    Located in N/W London HA3, and willing to travel within reason





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    Thanks ,Ive been reading the forum for a bit ,but i just registered ..


    You've lost me there bud ,do you mean a 12v relay to switch the power feeds ? or running the permanent feed (and ground) to the head unit directly from the battery avoiding the car loom?

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    Well i've onlt taken my permanent live to the battery and accessory to the battery via a 12v relay so it switches on on off still
    Want a professional job done on fitting your aftermarket electrical accessories? PM me for a quote
    Electrical fault finding also taken on
    Located in N/W London HA3, and willing to travel within reason





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    So if I run a supply from the battery (+) split it in two ,use one side as the permanant feed to the head unit and use the other side for the switched feed (accessory).I put the accessory feed through a (say 16 amp 12v) relay and use the switched feed from the existing car loom to switch the relay. Thus removing the loom from the equasion. I could also run the ground from the battery if i think it will help.

    sounds a plan...

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    Thats what I did
    Want a professional job done on fitting your aftermarket electrical accessories? PM me for a quote
    Electrical fault finding also taken on
    Located in N/W London HA3, and willing to travel within reason





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    Ta muchly i'll give that a bash later..

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    So...

    Tried above ,hiss didn't go away, and I started to pick up alternator whine as well,I took the Head unit out of the car, stuck it on a 12v transformer I have and ran the RCA outs into the Hi-fi in the house... and the signal is clean ..

    So I'm both pissed and pleased with that result as it's not the expensive head unit..but I'm now stuck for ideas again..

    Any more help gratefully recieved

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    I'm out of ideas now
    Want a professional job done on fitting your aftermarket electrical accessories? PM me for a quote
    Electrical fault finding also taken on
    Located in N/W London HA3, and willing to travel within reason





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    Bugger...

    I'm going to try a new HU at the weekend ,thanks for the help anyhoo

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