additionally, not all twelves have the same cone area, and neither do all tens. some tens with larger cone surfaces can move more air than some twelves with less.
subs with a "fat" surround may actually move less air with each stroke than a speaker with a narrower surround. in order to make up for their small cone areas, these subs have to make larger xmax to get loud - sort of a catch 22.
also, square cones have about 20% more area than round ones, and flat piston subs have slightly less cone area than those with a deep draw. this is why kicker L7s are very good at making SPL, and flat piston subs, although sounding good, are often very inefficient.
Sony is pretty much the worst car audio equipment you can lay your hands on. I highly recommend against you using their subs and consider getting 2 good 12s or 15s instead of those 4 Sonys. As far as bandpass, it's ok for SPL at centered frequencies, but if you plan to do any sort of music listening, I recommend ported. How much are you willing to spend?
well.. i have a friend with two sony 10s in a bandpass box and it beats awesome... im looking to spend about 1k
You have to ask yourself "compared to what"? I'm just forewarning you, their equipment is extremely poorly built, has a high failure rate, and you can simply get much better equipment for the money. Does that $1k include amplifiers and box? Also, do you have a head unit yet, or need one?
the problem with the solobaric is that to get more surface area by making the sub square, you sacrifice excursion. they have prety crappy Xmax which defeats the gains from being square, and they still sound like buttkiss.
glass, please describe exactly what kind of 'butkiss' sounds you've personally heard coming from an L7. i'm not interested in theories on how uneven stress points degrade sound quality, or how these subs supposedly don't take power or aren't well built - just some firsthand, objective evidence you have that an L7 does not perform well in the 10-80Hz range.
they sound lousy at high volume compared to better made round subs. As for experience, 15 years as an installer and pro circuit competitor. If you have some and like them, that's great. I won't use them myself. I used to be a dealer for stillwater design, so I have more experience with their products than I care to remember.