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aftermarket hu problems.

Discussion in 'In-Car Entertainment' started by combatrover, Feb 18, 2009.

  1. combatrover
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    combatrover LIVING THE AUDI DREAM

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    hi all we have a 97 a3 sport with the boss set up, and i have wired in a after market hu,the problem we have now is when the hu switches on, there is a "pulse" "pop" which ever you like to say from the rear speakers, does anyone know why this is? or how i can stop this? as am woried it will blow the speakers as it is very loud. also even when the hu is not on, there is interferance in the speakers, (a whine type noise.) any help is greatly appreciated. thanks.
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  2. alijames
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    alijames Active Member

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    A common problem. A search for "bose aftermarket pop" will give lots of threads on this.

    Cheers,
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  3. combatrover
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    combatrover LIVING THE AUDI DREAM

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    searched what you said to and cant find anything .
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  4. alijames
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    alijames Active Member

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    http://www.audi-sport.net/vb/showthread.php?t=47064
    http://www.audi-sport.net/vb/showthread.php?t=26307

    Both detail the problem and come up when you search for 'bose aftermarket pop'

    As these threads suggest, the the problem is caused by the input stage on the Bose Amplifier not being compatible with aftermarket head unit RCA outputs.

    Essentially 4 options :

    1. Use a speaker level -> line level adaptor to convert the head unit speaker outputs to drive the Bose Amp. Needs a bit of wiring and also produces questionable sound quality.

    2. Replace the Bose amp with something better, but you will probably need to change the front and rear speakers as the Bose ones are 2Ohm.

    3. Drive the fronts & rears off the Head unit amplifier, but as in option 2, you may have to change the speakers.

    4. Put a Concert or Symphony head unit back in and live with the Bose setup. You can always get an xCarlink or iPos adaptor, and an AndyMac sub will improve the bottom end drastically.

    Cheers,
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  5. combatrover
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    combatrover LIVING THE AUDI DREAM

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    we have an aftermarket hu, sub and amp, there is nothing of the audi bose bits being used. we have run are own wires through the car. any ideas?
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  6. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    All the stock speakers run off the Bose amp, so unless you have replaced all the speakers, all the speaker wiring and the Bose amp then you are still connected to the Bose amp that runs the cabin speakers and possibly the Bose tupperware sub.
    If you can give us more info on what system you are running then we can pinpoint the cause.
    Most likely you have the new HU feeding the rear speakers via the Bose amp, although you probably don't realise it.
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  7. combatrover
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    combatrover LIVING THE AUDI DREAM

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    The only standard audi speakers we are running are the 2 lower door speakers , which i have wired straight into the aftermarket head unit . The amp/sub and 6x9's are after market gear that i have wired in from scratch , havent used any of the boss setup or wireing , so when we come to sell the audi all i have to do is just pop the audi head unit back in and it will all work again .
    HU i wired the mem wire to the yellow wire with the red strip and the per live i wired to the white and red strip wire .
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  8. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    If you have the Bose setup then you need to disconnect the front speakers immediately. They are 2ohm impedance and cannot be run directly off any head unit. Continued use will fry the internal amp in the HU.
    You need to change them anyway as they are the most important speakers in the car and the Bose ones are dire, and the tweeters are made by Nokia!
    Have you rewired all the speakers or are you using the Audi speaker loom?
    When you replaced the rears did you rewire them?
    Is the Bose sub still connected?
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  9. combatrover
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    combatrover LIVING THE AUDI DREAM

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    have re wired all the speakers iam using , iam only using fli in the bottom of the door card . 6x9 in a stealth shelf i built because i hate seening 6x9 in shelfs . which i rewired again with the amp and sup which i rewired , i havent touched any of the boss loom , its all disconnected . left it all in just in case the missis gets board again .
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  10. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    As said, you can't run the lower front door Bose speakers directly fom the HU, they will eventually fry the internal HU amp, especially if driven hard. No HU will support 2 ohm impedance speakers.
    So the rears are rewired directly to the HU? What about the original Bose rears in the rear door cards and also the Bose sub in the rear cubbyhole? To get the popping you talk about you must still be connected to the Bose amp in someway.
    Have you checked that the Bose amp is not switching on with the HU?
    Unplug the Bose amp loom in the drivers side boot cubbyhole just to see if this solves the issue, and unplug the Bose sub as well.
    If you pull the HU can you post a pic of the wiring?
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