Originally Posted by markm3guy
Montr, Thank you for such an informative post. I've been following all the board posts very closely, as I too have a 328i (just bought it for my wife) and need to upgrade the base stereo...I am currently leaning towards the alpine setup.
I'n no expert, but it certainly would seem that the audio system is much improved by the Alpine system in combination with the head unit tone settings, as evidenced by the 'flatenned' spectrum.
Independent of the measurements....How does it actually sound? Understandable, the volume levels would be much better, but its it worth the price of upgrade in your opinion, or is it just a more expensive tin can?
I am glad that I did this change. This kit is a plug and play, no wires to cut or crimp and it is easily reversible. The sound quality is much improved and it can play much louder without distortion. The total cost including tax+shipping is $438 (kit) + $74 (door sails) = $512
The original midbass are cheap paper cone that rolloff after 10KHz. High frequencies are directional and because of the location of the midbass, you cannot hear them from the driver seat. Having a tweeter in the door and a better midbass make a big difference.
Here is the response of the original midbass driven by the HU with bass=0 and treble=0. The frequencies below 200Hz are from the woofer under the seat, not the midbass. As you can see, even with the HU boost at high frequencies there a rolloff above 10KHz.
Note: The efficiency of the new Alpine midbass is identical to the OEM speaker however the Alpine amplifier has about 9dB of gain. This means that the front speaker loudness relative to the rear speakers is increased. This can be easily corrected by the fader control. Also the gong is louder. This can be corrected in the sound menu of the HU.
One more thing. As other have found, the labelling on the passive crossover is wrong. Connector B2 is labelled "to Head-Unit". This is wrong, B2 go to the the tweeter, not the HU. Connector B3 has no label, it should be connected to the HU. This info is on page 7 of the 65 41 2 163 268 install instructions (found online).