Saturn,
thanks for the great advice :-)
I was looking at some diffferent crossover circuit diagram and also checked out some external crossover and eq last night as well. My first concern is, active crossover tend to robbed power and they will color the sound to a certain degree depends on the type and brand of components I'm going to use. I do not know how the Axiom and SVS's drivers going to react toward different filter slope. If I'm going to buy one, I sure as heck going to need the complete list of components they used, If I build one from scratch, then it'll be extremely time consuming and going to cost $$$$$, a first order design(6dB/octave), it is affected less by impedance variations than higher orders, BUT...the drivers will be producing sound at frequencies that are very likely outside their upper or lower limits. At low powers (<10w) is probably not a major issue, but it becomes much more important when I'm pushing >50w. The HK3480 is 120wpc so it's going to be much worst, scratch that!! :-)
Ok, so I go 2nd order filters(12dB/octave), it's better at keeping unwanted frequencies out of the drivers, but it's more complex, and affected by impedance variations to a much greater degree, it's very tricky and not a good idea to simply use off the shelf caps and coils from...say partsexpress, the capacitance used must remain predictable and constant over time and power as well. The kicker is, the possible variations(especially those caused by voice coil temperature) can totally ruin the sound regardless of the quality of teh components or care in making this crossover network. The whole design task becomes even more complex and the tolerances more exacting as the order increased, so 3rd(18dB/octave) and 4th(24dB/octave) order filters are going to be a MAJOR pain in the arse!!
And I still haven't take phase shift and filter alignment into consideration, no wonder Axiom Engineers designed their drivers the way they are!!! After much consideration I think I'll stick with the KISS rule to be on the safe side.
