Monster MotorsportChris Nott
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    Speakers Hissing after fitting pioneer avh5200bt to s3 8L with full amped bose

    Hi I have installed the pioneer avh5200bt to my aud s3 8L on an X plate, it come with fully amped bose system so the amp and 2 subs in rear etc i bought the following lead off ebay to keep everything the car Bose related working as normal - PC9-408 Audi Porsche with BOSE System Car Harness Leads on eBay (end time 05-Jan-11 16:06:37 GMT) it seems to do its job all speakers are working amped and subs are working fine. The problem i am having though is even when ther is no output im getting a hissing noise from the speakers sounds like its coming more from the back than the front if i turn volume up with no output the hissing gets even louder. When i play music from my ipod or a dvd etc sounds good but still slight hissing obviously heard less when volume is louder. The head unit is mean to be 4 x 50 w Mosfet which means its amped i think, my opinion is the head unit is sending an amped signal to the bose amp which amps the fequency again to create the hissing, doe this sound correct? If so how do I stop this can i stop headunit amping, surely loads of people connect a new head unit amped to a aftermarket amp dont they ? Please can i have your opinions would be much appreciated if you have an idea of something else it could be or how to fix this . THANKS CHRIS

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  3. #2
    Beardo's Avatar
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    You shouldn't connect high frequency outputs to an amp unless it has a dedicated high frequency input.

    High frequency = Amplified
    Low frequency = Non amplified (RCA Outputs)

    The one exception to this is a lead you can buy to convert High to low or low to high.
    Is this the lead you mention as the item has now finished and i couldn't see what you bought??

    If you haven't used an in line converter and you are inputting a high frequency signal into an amp not made for it that will be your problem.
    It could also be down to your cabling, have you run power cables paralell with the speaker cable? if so, seperate them or shield them as this can cause power buzz.

    Does it get louder as you accelerate?

    Other than this, hard to say without more info on your set up.

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    Sorry here is a fresh link to see the lead i bough PC9-408 BOSE Amp Bypass Harness Lead for AUDI PORSCHE on eBay (end time 31-Jan-11 16:09:25 GMT) I got this so the amp, subs & speakers carry on working with after market head unit. as far as im aware it does not get louder when i accelerate i will try when i finish work at 6pm just checked my my brother in law who fitted it for me said he th said they are not running parallell.

    Thanks
    Chris

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    Yes that's the speaker input adapter, you always get hiss and interference from the poor quality hi to lo converter that's built into it. You should be using the PC9-410 which uses the RCA output from the Pioneer rather than the high power speaker output. It is purely a wiring adapter with no electronics in between so you get a clean signal being fed to the Bose amp.
    However one issue with this adapter is possible popping when changing CD track, this is dependent on the HU, some are fine some give a loud pop. There's no way to tell, you can only try it to see if it's OK.
    Autoleads PC9-410 - Audi A3, A4, A6, A8, Allroad Wiring Harness Adaptor
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    ok what i have got the hissing down a little bit not so much there with music on so will have to put up with it for now until i can be bothered to bypass the amp and loose power of speakers etc is that the case if i use the pc910 still loose power of speakers using the RCA outputs? also the fascia i got jus dont seem to fit its not flush with the piano black trim does any one have a link to the correct fascia i need please. And any have the best option to keep this headunit but have good sound in my car ?

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    When feeding any amp, you use the low level RCA's. You only use hi-lo converters when you don't have RCA's
    "How to tear apart the ties that bind, perhaps fcuk off might be too kind"
    Alex Turner

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    ok thanks andy mac ill try the rca wire, the guy off ebay is saying the head unit just needs re-earthing that will stop the hissing, what do you reackon? or shoudl i buy the pc9410 wire? and also do you know the facia i need does is sit flush within the piano balck surround?

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    No, as said the hissing is perfectly normal when using that adapter. And as said you need the pc9-410 adapter.
    Depends which fascia you have, most need some trimming off the back to get them to fit properly. No Autoleads products fit properly. Try another make if you can find one. Didn't think there was one available for double DIN A3 8L
    "How to tear apart the ties that bind, perhaps fcuk off might be too kind"
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  10. #9
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    If it was an earthing problem with the stereo it would be more of a buzz than a hiss and it would almost certainly change or get louder the more you accelerate. sounds like the guy who told you that is making excuses or he doesn't know what he's talking about.
    As Andy said, get the right converter if you have to use one at all, separate your cables and you should be dandy.
    Where-abouts are you out of interest?

  11. #10
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    i have a spare pc9-410 if required. PM me
    57 A3 2.0 TDI Sportback (140)

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    Hi Beardo Thanks I'm in manchester ye i think he is making excuses, i'm just not keen on it popping when chnaging tracks but going to have to give it a try, sportstractor ill PM you now. It only gets louder with volume getting louder i.e if i choose AUX source when nnothing connected it hisses and hisses louder when increase volumer same if im using bluetooth for phone it very annoying. I do need to use a converter just to keep the bose etc

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    Hi andymac with the fascia issue i tried taking some off back had a celcius one or something but still not flush so ordered fp-02-05 see if that fits but is autoleads my is a snigle din though not a double din

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    damn fp-05-02 sorry

 

 

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