Replacing OEM headunit for Alpine headunit and subwoofer and amp. HELP

thestable

thestable

Member
Hi folks.

Bit of a call for help.

I’ve spent the afternoon trying to get the alpine headunit working and wiring in the amp and sub.

Firstly.

The factory head unit was not a Bose. A conxert I think.

I’ve bought Audi > iso harness < alpine harness.

Amp is wired in no worries there.

At the moment. I’ve got speakers in the back but nothing coming out of them. In the front they are REALLY quiet and sound dreadful.

As far as I can tell it’s wired up as it should be. Stuff turns on when it should (the head unit)

What am I missing. I could really do with help. After spending a day doing it. The last thing I want to do is take it to a shop to sort and pay them!

Apart from that. Once I’ve figured out what’s going on there.

When I connect the sub to the head unit there some serious interference in the speakers. Like bleeps and ticks. Very strange.

Any help would be really appreciated.


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Sounds like your speakers are earthed somehow. You do realise that the rear speakers have amps on them? You either should bypass these and use the head unit amp or feed them with low level line outputs, usually RCA on the head unit. I suspect the ISO converter you have does not do that.
You should have a diagram on the concert to help you identify what does what.
 
Just the sub.
I shall have to investigate further then and figure out how best to do it.


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There is a separate amplifier for the rear speakers which is powered on by the CANBUS of the OEM head units. This why whenever you buy a "standard" loom to fit non OEM stereo it usually doesn't work as the amp isn't turned on. I believe it is do-able, but re-wiring it may be one idea.
 
I tried to patch into the existing speakers using a replacement amp and tapping in to the wiring after the head unit and couldn’t get it to work well - I could only get reasonable volume by turning up to near max and the sound was crackly and awful.

I never did figure it out - I ended up just installing a Connects2 on the back of the Concert2 and that works perfectly for me.

Good luck. I’m sure Someone else will actually be able to help.


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All you need to do (assuming everything else is wired correctly) is lift the floor panel, remove the amp and join the wires together taking note of the polarity. What I suspect is happening is you are trying to put high level (speaker wires) through the amp instead of line level (RCA). If that makes sense?
 
Thinking back, I’m pretty sure I didn’t disconnect the amp in the footwell... ? at the time, I didn’t know those panels could be accessed or that there would be an amp in there! ?
Hope this helps Thestable.


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We’ve given up. Ive got an electrician with me and we both are stumped. So I’m going to pay the money and make it someone else’s problem. Why can’t things be simple!!


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Not sure I get it? If you look at the concert unit it tells you which cables do what, can you not just find a live, switched live and neutral, then just connect those to the new stereo's inputs, then simply use the front speaker wires and it should work. That just leaves the rear speakers to then deal with as I said above. Or am I being too simplistic?
 
there was sound coming out of the speakers at the front but REALLY quiet. there is interference carrying on everywhere so got knows whats going on. perhaps it's not earthed correctly.
 
That’s probably because you are sending speaker outputs through the Audi amp. Can you not just take the amp out and lash up a temporary link to see if it works?
 
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