An Auxiliary Audio Input to the Audi OEM Head Unit and CD Changer
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My plan is to provide an auxiliary audio input to the Audi OEM head unit and amplifier, on most newer Audi cars, equipped with the CD Changer. This applies to the allroad, A4, A6 and TT, as far as I know.
This should work with the 'Symphony' and 'Concert' head units.
This small self-powered unit would allow the operator to use MP3 players, the Apple iPod, and other portable devices that have a 3-cond. stereo mini-jack output port.
All of the normal controls on the head unit will work for the selected Auxiliary audio source.
To use the new Aux. input, you simply select the CD changer with the 'Mode' button on the head unit, and toggle the the switch I add.
The head unit will still display 'CD'.

Here are the basics of what I have done to some 10 different Audis.

I pull the head unit, and locate these wires on the top connector, like is shown here.

I will need to cut these red and white cables, to wire in a relay at this point.

These wires correspond the the line level outputs of the CD changer, and the input to the head unit on this familar label here. Look in the lower left portion of this label.

The relay will toggle between the CD changer input, and the Aux. input. Refer to this assembly here.

Basic Schematic.

The mini-plug cable will come out below and to the right of the ash tray, sort of like this.

A cable to power the Apple iPod, (It's a FireWire connector) can be located in this area also. It would be connected to constant 12V power.
Other power sources and voltages can be supplied also.
Switched or constant 12V power could also come from the RJ-45 jack in the TT, or other Audi cars, by routing the appropriate signals to this jack.

It could also be made long enough, to run along the bottom of the center console, out from the area under the ash tray, and come up between the center console and the passenger seat.

It may also be possible to run this cable into the center switch area in the center console between the seats. I need to explore this yet.

The best and easiest place to mount the switch and LED are next to the cig. lighter, here, in the ash tray.

Of course this means opening the ash tray to switch in the Aux. Input, but if you use you aux. device as a primary source of your audio, you won't be switching this back and forth a great deal.

Another look, a bit larger.

Here is a view of this connection using an Apple iPod. I provided power for the iPod also.

This is my personal install. I routed the stereo cable under the center tunnel, and up through the small rectangular neoprene spacer used for the phone cradle.

I can stuff this cable into the space below when I'm not using the iPod.

I used a Radio Shack cell 'generic' phone holdere, along with the Audi phone bracket.

By Jeff Bipes