Originally Posted by spike98
I am assuming its actively x'd over at the amp or the head. AFAIK its just one amp for the whole system according to some schematics i looked over. I read a post on here that it rolled off heavily at around 70hz. Ill have to see if i can find the post. I know it sure sounds like it doesn't play much under 80hz.
The Alpine premium factory amp is a 7.1 DSP unit using Alpine's Euphony Surround Sound processor similar to the same concept that JBL/Harman uses in their Logic 7. The unit contains it's own crossover points and does bi-amp to the speakers. The 8 inch subwoofer works in conjunction with the front door speakers creating the front stage. The center signal is the sum of left and right channel of the front stage. To date, I have yet to come across any information on the crossover points or how the wattage is broken down. Other forum members have reported after taken out the front speakers, the magnet's were extremely light. Therefore, IMO the speaks do not need much power to push them and the majority of the power is devoted to the sub. Remember, Alpine has to work with the design spec issued by Chrysler.
Spike98, your assumption is correct that is an active system within the amp. My theory is the 6x9 is crossover even lower and has a low slope of 6 or 12 db to compensate for the lack luster performance of the sub.
Their are many ways to upgrade the system in order to solve your problem were to connect the subwoofer and to improve the overall quality of the sound if you do not want to scrape the entire system. I would upgrade of course starting with the sub (JL Audio's stealthbox does a wonderful job) and aftermarket amp to power the sub. However, I would also install a new 4 channel amp with a crossover unit/eq bulit-in or add a separate crossover/eq unit to power the front door speaks bi-amped. Which means I would connect the sub to the front stage by summing the signal from the sub and also all the front left and right channels. And, if you want later, you can change the front speakers to a better component system using the 6 1/2 speakers instead of the 6x9s in order to get true mid-bass punch and do not use the passive crossover since you be using the crossover/eq unit (speaker companies for example: Morel Hifi, Focal, Helix, Brax, Pioneer, Kicker, etc.). This method you can tune the system to way you like listening to your music or videos. This setup is most likely more than you want to spend, but it is worth in the sound improvement without spending for whole new system. The rest of the Alpine in the rear door and hatch area you can keep as the rear fill, it might sound right to you for your application. Down the road, you can kill the center channel speaker, replace it or keep the existing.
To sum the signals, I would suggest using the Audison Bit-Ten processor, it has the five channels needed and contains dsp unit to set the eq, time delay and crossover points. Or can get an all in one unit from Zapco Amps.
Next year, I going to scrape everything and start fresh.
Best for now.