what if i replaced the drivers and ran the system active?
Even if you go active, you still have to shape the response of the filters to the drivers. Active and passive design is quite similar in concept, but the execution quite different. You still have to build them or buy ones whose slopes are highly controllable. Three way speakers present a real headache, which is why there are so few good ones. Getting the slopes of the band pass filter right is very difficult. Also there are very few good mid range drivers around with a high enough band width to execute three way designs with elegance.
For a good three way design you need a mid range driver with a band width spanning a minimum of four octaves and five if possible.
If you want to start on in the hobby of speaker building, I would start with something less ambitious.
The other problem with your plan is that you will be working the woofer selection backwards to the box you have. This will limit your choice, and make it hard to select drivers that are a promising match.
I can't emphasize enough, that the start of a good speaker design starts with selecting drivers that show promise of making a good functioning whole.
So often the novice starts out looking for the so called "best" drivers, with no concept of how to make an excellent sum of the parts. Worse yet, they have often purchased the drivers before asking for help!
If you look at any driver, you will see they all are essentially band pass devices, that have a top and low end roll off. These roll offs become part of the whole crossover design. In other words if the design calls for a fourth order roll off for a crossover point, then the crossover must take that into account and be second order. More often than not roll offs are complex and change orders, ans so the crossover has to as well. Then there is the matter of having to keep an eye on the practical limits of drivers, for example cutting off tweeters well above their resonant frequencies. The crossover also has to EQ out resonant peaks in drivers, even outside their band pass. And all this while paying attention to time and phase.
Finally impedance curves of drivers often have to be dealt with in passive crossovers, and the sensitivity of the drivers matched whether active or passive.
I hope this will help you see, that, after sound minimally resonant cabinetry, the crossover really determines how the speaker sounds, whether it has active or passive crossovers. All things being equal there are a lot of situations were an active solution has advantages over a passive one.
