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High pitched noise from rear speakers

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by Jay4, Aug 28, 2007.

  1. Jay4
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    Jay4 Member

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    [Aug 28, 2007]
    i've recently swapped the Concert 2 headunit in the car for another (non audi) headunit and am getting a high pitched noise from the rear speakers when the headunit is switched on. The noise is constant so is not too bad at high volume but if the headunit is fairly low on volume, the high pitched noise can be heared through. Any ideas what this could be?
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  2. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Aug 28, 2007]
    Is it alternator whine (does it go up & down with the revs) or something else?
    If it is then try earthing the chassis of the HU to the cars chassis behind the glovebox. Also what adapter are you using to connect the new HU to the rear amp?
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  3. Jay4
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    Jay4 Member

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    [Aug 29, 2007]
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  4. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Aug 29, 2007]
    that's the speaker input adapter which could be the issue. Essentially it's taking the amplified speaker signal from the new HU and reducing it down to a pre-out signal, only to be re-amplified again by the Audi rear amp. This is prone to creating electrical noise as the hi-lo converter is bound to be poor quality.
    Maybe worth trying the RCA input adapter (as long as the new HU has rear RCA's) as this is a far cleaner solution.
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  5. jase0851
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    jase0851 Member

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    [Aug 29, 2007]
    i just ran new wires from the headunit to the connector block in the rear which was pluged into the amp, under andys advice, and the rears work a treat now much better than before. need to wire up the head unit properly next
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  6. Dan klang
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    Dan klang D9N_Dk

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    [Mar 25, 2015 at 6:52 PM]
    Hey sorry to drag up a really old thread but here is my problem

    I've fitted an aftermarket head unit with the same adapter you have used and I too get a buzzing from the rear speakers that's driving me mad. I've been searching and searching the Internet and have found a couple of threads where people have the same problem but in all the threads no one has an answer or can cure it or get around it. This is the only thread I've seen where it may be possible please could you tell me what new wires you run from the adapter to the rear amp as i want to do this thank you or does anyone else know many thanks
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  7. dualmono21
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    dualmono21 Well-Known Member

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    [Mar 28, 2015 at 12:58 PM]
    basically
    try running a rear rca output from your headunit into the standard amplifier as opposed to two convertors
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