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Rear Speaker Help Pls

Discussion in 'A4/S4 forum(B5 Chassis)' started by Tooand, Jan 6, 2013.

  1. Tooand
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    Tooand New Member

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    [Jan 6, 2013]
    Hi I fitted a new Sony head unit to my 1999 A4 saloon non-Bose,as the old unit was looking dated(it was also an aftermarket HU). I have never had sound from the rears so came on here for help and found all I needed was a PS9- 404 to fix the problem, but it hasn't. If I fade all the volume to the rears you can just here it so there is something there, have I not done something right I'm baffled
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  3. Tom_B
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    Tom_B Member

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    [Jan 6, 2013]
    The rear speakers are powered by the little amps built into them so they are wired at line output level. I wonder if the previous owner has changed the wiring somehow.
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  4. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Jan 6, 2013]
    You will have to fade to rear quite a bit to balance the sound as the rear amp is only 2 x 20w and the new HU will be chucking out over twice that power to the fronts. Far better to rewire the rears directly to the new HU and just bypass the hopeless rear amp.
    Have you connected the blue flying lead on the PC9-404 adaper to the power antenna 12v output on the new HU? This is the trigger to turn the rear amp on, without it the rear amp won't turn on.
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  5. Tooand
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    Tooand New Member

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    [Jan 6, 2013]
    Thanks for the response guys, I have plugged the blue amp wire from the HU loom to the blue wire on the pc9 404 one had a male end and the other female so presumed they went together, I do have a lighter blue wire for the aerial coming from the HU, does that need to be connected, like I said I do have sound from the rears but very quiet and bassy
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  6. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Jan 6, 2013]
    As said you need to rewire the rears directly to the HU
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  7. Oranoco
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    Oranoco Well-Known Member

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    [Jan 10, 2013]
    As has been said mate you need to run a new set of wires straight from your new HU to the speakers.
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  8. AR-rkon
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    AR-rkon BZZZZ.... caffeine fueled electrical engineer Regional Rep

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    [Jan 10, 2013]
    before wiring the rear speakers direct to the HU, it may be worth sticking a meter on them and measure the impendence.

    My full bose has 2OHM speakers, which if powered from an aftermarket HU, will burn its internal amp out. Aftermarket HU's are designed to work with 4OHM.
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  9. Oranoco
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    Oranoco Well-Known Member

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    [Jan 10, 2013]
    Pretty certain only the Bose units run at 2ohms. I pulled out my factory rears and fitted a set of old Kenwood Dualmags from my old Fiesta.
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  10. AR-rkon
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    AR-rkon BZZZZ.... caffeine fueled electrical engineer Regional Rep

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    [Jan 10, 2013]
    I think it is only the Bose, didn't want the OP to blow his stereo :lmfao: god knows I did it first time round haha
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  11. Tooand
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    Tooand New Member

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    [Jan 13, 2013]
    Well I solved the problem, I bought another car. Another 2.8Q but automatic this time, it's fitted with a Bose Symphony system so I've got plenty of speakers in this one(this wasn't the reason I bought it, just fancied a change and an automatic). Thank you for all the help though
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