two-way vs. three-way crossovers
I've got 2 pairs of Infinity Kappa 693.5i's in my car that im powering with a Power Acoustik SP4X-800 (85x4 at 4 ohms). I have a pair in my rear deck, and the other pair are in custom built boxes, flush mounted in between the two front seats and in between my 2 rear seats, both on the floor. They sound pretty good, but at times certain frequencies seem to be a little off. It's hard to explain, but they just don't sound right. I'm gonna invest in a crossover to attempt to fix this problem, but I have next to no experience with electronic crossovers. What is the difference between 2 way and 3 way crossovers? I assume a 3-way would be optimal in my case, since the speakers are 3-way, but i'm still curious. Also, what would be the best settings to set the crossovers at?
I was looking at this one - http://www.etronics.com/product.asp?stk_code=audax303x - any opinions?
Thanks in advance