Auxiliary Input to the OEM- Non-Bose Upgrade Head Unit
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These mods were done on a Roadster, with the OEM 'Concert' Head Unit, and the Non-Upgraded Audio system.

The process I document here involves removing, dissasembling and modifying the OEM head unit.

I chose not to buy the 'Blaupunkt'adapter to do this. You could use this also, but if you are still using the OEM rears power amp, you would still need to tap into these line-in wires at the connector, and solder in a pair of RCA plugs. Some may think this is an easier alternative, and it certainly has merit, if you are at all concerened about taking the OEM head unit apart, as I did.

The reason to take apart the head unit, is to solder a pair of RCA jacks onto the 'Front' line-out pins. The non-upgraded sound system in the 2000-01 TT's use the amp built into the head unit to power the front speakers. In order to get the line level outputs from the OEM head unit for the fronts amplifier, it's necessary to by-pass the cable connector from the OEM wiring loom. There are no wires coming from this connector for line-outs to the front power amp.
There is no front power amp.
The amp for the rears is still being driven by the existing connection from the head unit to the power amp. Refer to this drawing.

It compares to this part of the rear connector.

So, are you ready?

Start by removing the radio. Unplug all connectors. Take off the top and bottom covers. 5 screws to do this. Look at the radio from the rear. Remove the screws, 2 in the black plastic connector, and the 3 other plated screws. You can then remove this back panel by unplugging it from the 2 small connectors on the main radio circuit board. pull and wiggle it gently, and it will come right off.

I took apart the back of the radio to get at the circiuit board for the rear connectors.

I soldered two molded RCA female jacks at these points. You don't really need to worry too much about doing this. Work carefully and take your time.

I ran the cables behind the circuit board, and out the bottom of the head unit. I re-assembled the head unit.

I had previously installed another head unit, that had 4 line level outputsm, fron fronts and rears, lefts and rights. To power the front speakers, I used a small, 20 W stereo power amp, that is mounted under the dash, behind the lower dash panel. This allowed me to replace the front speakers with a pair of MBQuart RSD-216 speakers. They have a 6.5" woofer, and a 1" tweeter, with a cross-over box. They are exact replacement fits for the OEM speakers. (That was a separate install that was not documented. It's easily done.)

In this dash area then I had to wire the output of this small amp, to the speaker connector wires, this yellow-tan connector in the picture. I spiced into the wires, soldered and taped the connections. This connector does not get connected back onto the rear of the head unit.
The power connections for this amp get tapped in at this black connector.
The 2 RCA jacks in the blue tape are the line-outs from the connector on the head unit, that goes to the rears amp. These jacks are not used at this time, but will be used to drive the inputs of a different power amp.
Remember, the OEM connector hanldes this for the OEM power amp.
The pair of RCA plugs, mate to the RCA jacks that I soldered in on the rear of the circuit board.

So, if you want to do this, you will need to get this adapter from



It's $69.95

Note: There is NO OTHER way to get an auxiliary input int othe 'Concert' Head Unit, unless you use this type of an adapter. I do not make this adpater

I do not sell this adpater.

You will need to remove;

The 'Concert' radio.
The rear trunk cover, roadster
The rear cubby hole protector, roadster.
The cubby hole door behind the front seat.

Replace the Head Unit

Replace the radio/head unit, replacing all the OEM connectors, except the front speaker connector. Plug in all the RCA plugs. Turn the ignition on, and restore the head unit from the 'SAFE' mode. The radio should come on, front and rears. The other really cool thing now about this mode so far, is that the fader switch will work.

In order to get the adapter plugged into the 13-pin DIN cable, and route it through the area behind the seat, you need to "Modify" the rear cubby hole. Here is a view of the cable and the rear of the cubby-hole.

I cut a small hole in the top corner of the back of the cubby hole for the connector. This material is not plastic, but a type of thin fiber-board like material. It cut easily with a hobby knife.

I ran the yellow 13-pin female adapter end through this hole from the inside of the cubby hole behind the seat. it fit snug in the hole. Then I plugged the male cable into the adapter.

I plugged a RCA male to 1/8" stereo mini plug adapter cable into the RCA females of the adapter. I replaced the cubby-hole door, and ran this plug out on the passenger seat.


Plug the 1/8 mini-plug into your favorite MP3, Ipod, Portable CD player, etc.. Turn on the radio. Press the 'Mode' button. You should see this.

Hit 'Play' on your auxiliary unit, and it should be playing through your head unit.


photo by jeff bipes
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By Jeff Bipes