lol have fun with your Alpines!

 

Each to their own on the brand I guess, but I'm still perplexed by your "up to 400hz" statement? My mids start at 150hz; I've never heard asub play that high, not ever seen an amp with a x-over setting that high- propbably for good reason. If you REALLY want your subs to go that high, try starting around 80hz and turning the x-over up from there and see if you'r ehappy with how they sound. Even modest 6" would do more than adequate midbass from 80-400hz.

 

No matter with that? lol.. you my friend are clueless.

 

another box design that may work is a transmission line subbox

you will not need alot of power and they are efficient
downfall is that they are a larger box (mine is 6 cuft for one 12 inch sub )

 

From what I understand a properly designed and stuffed transmission line is know to be fairly inefficient. Maybe if one foregoes the stuffing the efficiency increases, but realistically this design would probably not work very well for the OP's situation.

Can I recommend Creative Sound Solutions subwoofers - I just bought an SDX10 from them and am very impressed with the value and low distortion. http://www.creativesound.ca They also have a 12" design and some passive radiators avaiable. They're very versatile subs that can work in a variety of different box designs - and they're Canadian.

 

here is an old video i found on youtube on transmission line sub box

 

dbs, I wasn't trying to knock t-lines - I'm a huge fan of 1/4wave box designs - I was just suggesting that it probably won't work well for behind the OP's back seats, particularly given the response range he's shooting for. A 12" driver will need a significant size TL box to get down to 22Hz.

Also, here's a quick summary of properly designed TL characteristics from http://www.mh-audio.nl/Transmission%...udspeakers.asp

 

Didn't think you were knocking t-lines just showing another option,
my variation of t-line boxes don't have anything in them except air

Nice article tho