New to the forum.
Just bought a '91 S4 Slate Gray that is in excellent shape. Fixing a few niggles frm the PO's and one main pain was the Stuttgart head.
It had a BT cassette soldered inside which I though was a jammed tape
Tried to removed it and messed up the shuttle mechanism a bit; not a worry as I didn't want the 10 CD changer and cell phone stuff anyway.
Phone remains in the cabin though as everyone thinks it's cool.
I am replacing the head with a new modern Frankfurt/Bremen unit. When I pulled the head I noticed the pre-amp DIN connected and the 4 main high level plugs taped off.
Does anyone know if I can just connect those to the new powered head unit? Do they bypass the pre-amp?
Porsche put them there so I "assume" they would be functional on a lesser spec model.

PS Just had a look at the shop manuals and it shows 6 outputs from the passngr amp to the speakers and not 4 at the head unit. Presumably the impeadance would be wrong given the way they have arranged the rear crossovers. Hmmmm

Cheers

 

You will need the pinout of the din connector at the amp end.

Generally it is a bunch of (6) low level input wires, a signal shield ground, and a signal power for remote amp turn on.

Once you have the pinout of the din, you can buy a generic 8 pin female plug with RCA connectors and connect it to any head unit with the appropriate amount of outputs.

For this you can use RCA Y connectors to turn the rear 2 channels into 4 channels to satisfy the 6 channel requirements for the amp

Or you can get creative and get something like an ADS 642.

Bypass the crossover network and use it to convert RCA to a single din connector so you can connect any head unit with 4 RCA channels to the din plug.

Your call

 

Oh yeah. Blau and Becker used those dins on headunits back in the day for OEM integration like we have in our cars and the RCAs were mostly for aftermarket use.

Mostly so if your model didn't have an external amp, you could add one for a full system or a sub.

 

I have the amp beside the passenger seat.
The PO said the stereo didn't work through all the speakers and I have noticed it "mostly" works.
I will rig up a test signal tomorrow to verify what works through the amp but what really has me guessing is why I have 4 sets of high level wires capped off behind the head unit with black tape (did Porsche ever use black magic?) and where do they go.
They don't seem to be in the workshop manual but they are definitely factory.
If the amp tests out ok I can break out the DIN.
Oddly the manual shows no DIN connection or pre outputs on the radio to the amp; the signal get there magically. Under GTS it shows the DIN connection to my rear CD changer and Cell phone booster but still no radio ouputs, DIN or otherwise, to the amp; just power, grounds and an evil set of alarm relays I may have to ground out.
Hunt continues and I'll report back.

 

Those high level wires were for a lower optioned car.

Porsche just left them in the wiring when they made the harness.

Basically you had 8 speakers instead of 10 with the rear ones driven off of a 4 channel amp and the high level wires powering the ones in the door.

Weird, but it worked.