Help, Rear Speakers

[Audiruss]

Hi everyone,

I've just bought a lovely A3 1.8T Sport, my first Audi and so far love it. Today I've bought a new Alpine Head unit, works fine bar the rear speakers not working, I've tried finding the rear speakers cables so then I can just join up the cables from the alpine but can I find them?? NO!! Any ideas? I'm sure this has probably been covered before.

Many thanks.


Russell

[loki]

Same problem with the Alpine iPod unit. I've never managed to sort the problem, but I did see a response here before that you needed the correct ISO adaptor to make the rear speakers work.

If you go on to the Halfords site, you can search which one you need and then that you have the correct one.

[Dee Keenan]

If your Alpine unit is new (2007/8 model) then use PC9-401 (converts to rears into speaker ISO), if it is an older model, then use PC9-404 (converts rears to phono). Which ever you choose, dont forget to link the blue/white wire on the PC9 loom to your Alpines Amplifier Remote Output.

These would both be available from either your local Halfords store, or from a multitude of on-line sellers.

Dee

[loki]

Should have updated this!

After pulling out loads of cables and wires that weren't connected to anything. studying the wiring diagrams of both my car and the head unit - I'd simply not plugged in the blue wire. It was literally a 30 second job - the bass is incredible now!

D'oh!

[museumsteve]

On this subject, I've just added the harness (PC-401) to a JVC headunit which I've put in my A3 (with Bose half amplified system) and I now get a hissing from the rear speakers even with the ignition and stereo off.
Any pointers? Really concerned that if it's getting power from somewhere it could drain my battery if left for a weekend unused.

[museumsteve]

After some digging round I've sorted some of the issue.
The Audi wiring is back to front (as many know) so the live feeds need reversing into the HU. So I plugged the yellow into the red and the red into the yellow, this sorted the permanent feed issue, I then added the blue/white striped wire to the Yellow which is the switched Live and this stopped the hissing when ignition was off. However I still have hissing when the stereo is on, I'm wondering if it is just a naff system or maybe has been hammered prior to me getting the car.

[Dee Keenan]

Hi museumsteve

Hiss covers such a broad spectrum of issues in a car. The most common is Electronic Interference, the second is Ground Looping. To aid in identifying which is the cause, switch your stereo on with the engine off - mose electrical interference comes in only when the engine is running, ground loop is there all the time.

Electronic Interference - This noise is transmitted down the electrical wiring system of your audio unit. If you are only hearing it on the rear speakers, then this would suggest (if it is your issue) that it is travelling through your 'Amp Remote' wire, the power you connected to the blue/white wire of the PC9-401. The power for this wire should have been taken from your new stereos amp remote output, so if you have selected a different location (ie ignition source) then do swap it onto the units output (usually a blue or a blue/white wire) as this utilises the units power filter. If, when you have taken it from the correct position, then it would point to an interference coming from the unit itself, you still get interference, rather than finding the cause of the contamination, fit your own power filter on that line (between the units wire and the PC9-401 blue/white). You can pick up power filters (also known as in-line chokes) from many places, make it a minimum of 5amp, there is no maximum you would need to watch for, so whatever you can lay your hands on (Autoleads part number PC8-223 is a 15amp choke).

Ground Looping - if PC9-401 (or PC9-408 on full BOSE) is used, then this would not be an issue as the lead uses the speaker outputs from the stereo, this could occur if a P9-404 (or PC9-410 on full BOSE) is installed using the phono outputs of your new stereo. And, as the name suggests, is caused the the negative shield of the phono's coming from a different chassis ground to the amplifier, causing a loop between the earths and it is a form of magnetic interference. In these circumstances, a Ground Loop Isolator would need to be installed (Autoleads part number PC1-620).

The part numbers given here are for Autoleads manufactured products and are given only because these are what I know. Use of your internet search engine on descripions such as '12v POWER FILTER' or 'GROUND LOOP ISOLATOR' wil bring up a wealth of on-line sources.

Dee

[ini]

Depending on your head unit and bose/non-bose etc, some of the old non-bose true 'stereo' system had front speakers driven by the headunit, and rears on preouts with a mini amp on one of the rear speakers.

This would obviously have to be removed if driving from a 'new' headunit or amp.