Heidelberg Head Unit replacement in 1993 B3 Passat

(Aktiv System)

The Heidelberg head unit and Aktiv speaker system are actually not that bad. But if you are looking for a CD player and don't want to install a changer with FM modulator, you will end up replacing the head unit. Many people have suggested that owners completely remove the Aktiv system and do a new install from scratch. Depending on what your audio goals are that may be a good route to go. But, by using an installers harnesses no wires on the factory harness have to be cut. This makes removing the deck and reinstalling the stock unit easy.

For this upgrade we selected the Clarion DB345MP head unit. It has Front and Rear RCA outs. And the line level is 1.8~2v @ 0db. Searching on VWVortex I found that when upgrading the head unit it was wise to stay around 1.45v levels as much more would surely fry the Aktiv amplifiers. Since I didn't have a scope handy to check the levels on the Heidelberg I took the posting as a guideline during shopping. Although finding the line out voltage for the DB345MP was a PITA because it's not listed anywhere, some random google results returned that the output was 1.8v while another reported 2.0v. I decided to take the chance on that range in hopes that we don't often have the deck running at 0db.

There are downsides to running the existing Aktiv amps. Mostly that they supposedly only put out 8-10 watts. So there will be no bumpin beats coming from your car. From the sounds of things the dash and front door speakers are of sufficent quality, but I would like to upgrade the rear deck speakers.

It took about 4 hours from everything in boxes to having the deck installed. That included a 30 minute trip to Main Electronics to pickup some RCA connectors and shrink tubing. All in all the whole installation was smooth. Only hassle was during the final installation trying to move all the wiring away from the rear of the deck so it could slide back properly. Only became frustrating because I didn't want to remove multiple panels to access the rear of the deck. Only removing the glove compartment prooved to be sufficent.

The installation went as follows. Click the pictures for much larger versions.

Little (not realy) deck removal tool made out of coat hanger. It does not need to be this long. 2-4" will suffice.
	Heidelberg deck removed.
Connector pinout diagram atop stock deck.
	Picked up a Scosche VWK1B and a VWA2B from A&B Sound for $15 each.
Antenna Amplifier/Adapter and Installer Harnesses from Scosche.
	Wiring harness provided with the Clarion DB345MP
Took a picture of the wiring colour codes for the head unit. Looks pretty simple.
	Because we're replacing the factory Aktiv enabled head unit, a bunch of wires can come out of the install harness. The connector looks to work for vehicles with either Aktiv or non-Aktiv setups. The 8 speaker wires are not needed and can be removed. There are also 2 brown wires to be removed as they do not connect to anything on the deck. According to Scoche technical support the two brown wires are 'data lines'.
Once the wires for deck power and such have been connected, your cross connect should look similiar to this. I tied off the speaker leads on the Clarion harness for future use, but this prooved to make more work getting the deck installed. Shortly after this they were removed. This shot also shows the blue/white wire disconnected. It gets connected to the switched 12v line as it triggers the Aktiv amplifiers in the doors to turn on.
	Because we're using the factory Aktiv amplified speakers we need to take the installer harness and add some RCA connectors to plug into the line level outputs on the DB345MP. On this connector there is an extra blue/white wire that does't have a matching connector on the factory harness, so it was removed. On this connector there are leads for FR, FL, RR, RL and a ground lead. The RCA connectors were connected to the correct coloured lines and all share the single ground wire.
Here is a shot of the above connector finished and plugged into the head unit. Too bad Clarion made one pair of RCAs on the rear panel, and another pair on a dongle. Looks like ass and makes a little more wire mess to fit into the stock deck location.
	Both connectors are finished and ready for installation. The VWA2B was also connected to the 12v switched line. The antenna is an amplified unit which uses an external amplifier for aftermarket head units. After doing it this way I would recommend to others to leave a little more slack on the power line than I did.
The looped off speaker leads looked like they wouldn't cause any problems....
	.. But were removed as they caused a little too much interference when installing the head unit.
New head unit installed sans faceplate. I'm personally not a fan of the surround, but there doesn't appear to be a better alternative.
	Installed with faceplate attached. Everytning is running properly.
Another shot of the finished product.

Only took a few notes when making the harness.

I did not take pictures of the actual deck installation as it is pretty standard as aftermarket decks go. Now that the installation is complete, doing some test listening it all sounds quite good. The next step is to replace the rear deck speakers.

Links from researching...

http://forums.vwvortex.com/zerothread?id=1157056

http://www.corrado-club.com/aktiv/

-nils (march 7, 2005)