Originally Posted by Technic
The crossover circuit is an LR design, with 3 levels of tweeter attenuation (depending on the sound system installed -Business, Professional HU, iDrive):
I think my passive crossover is different than your crossover. I have the 268 kit, not the 684. The crossover has 2 wires on the inductor side and 4 wires on the other side. I can see the inductor on one side. On the other side I can see a resistor and a capacitor. Measurements with a DVM confirm that there is a capacitor in the path.
I think the crossover is a first order lowpass for the midbass (1 inductor). For the highpass to the tweeter, it is a first order (1 capacitor) with some attenuation (1 resistor).