I am currently installing an aftermarket sub-woofer, amp and components. I am using the oem head-unit and bought a line output converter to hook-up to the rear sub-woofers (stock in my limited), then plug this into the amp input. However, today when pulling the crossfire apart I realized the stock sub-woofers are amplified (with an additional amp under the passenger footwell) and they look like they are dual voice coil (because the four wires going to each speaker). So, my question is how do I hook-up the line output converter? Also, can I unplug the rear subwoofers, so I don't lose quality in my bass, without messing up the factory amp or head unit?
Thanx to any replies.

 

I can see that this reply is a little late, but to anyone else, using a QUALITY line output converter behind the radio will yield best results in the crossfire, using the rear outputs. This will give you the best signal to connect aftermarket equipment. I have done a complete sound system in my base model including MB Quart components up front, an Audison LRX4300 (mounted behind the drivers seat) for the speakers bi-amping them, (2) MB Quart 10" Subs with a JL 500/1 (mounted behind the passenger seat), Alumapro 5 farad cap) mounted under the carpet under the passenger seat), an Alpine CDA9835 headunit with ipod adapter in console. I ran new wires for everything so if you have any question about installing anything in the crossfire, PM me.

 

You really don't need the line level converter. Assuming you are using an amplifier with differential inputs you can tap directly off the factory amp and run those inputs directly to the aftermarket amplifier. The benefit to this is that you retain the factory eq, crossover, and limiting circuits used on the sub channel.

The subs in the is car are dual voice coil so you will need to pair up a left and right to feed the amplifier for maximum signal.

 

Some of that is true, but not recommended. Not using a line output converter would work if you were using an amp that could accept a high enough input voltage. The JL 500/1 for example is capable of accepting up to 8 volts of input, but that still needs to come from the radio, not the factory sub amp. If you did use the sub amp, you would be retaining the factory amps EQ, which is something you do not want to do. The factory amps EQ is there for the factory speakers. If you use an aftermarket system, you do not want to use the factory EQ. this is why devices like JL's Cleansweep were created, to remove factory EQs. While they improve the factory system performance, they degrade aftermarket equipment response with unwanted highs and lows in frequency response.

Just another point, if you read the post about a factory changer for the nav radio, MMZ_TimeLord has posted the wiring for the radio. This wiring is the same wiring as the blaupunkt radios. if you can get the RCA out connector from your local Blaupunks dealer, this will plug into socket C3 and give you line out. I don't know if there is any output on that connection, but there usually is in other german cars that I have worked on. This would be the best way to hook up an aftermarket amp.