frequency response issues with kicker sub

ok, i have a kicker L5 15 inch sub(the square one) in a 1.5 cubic feet sealed box at the moment.  i am powering it with a kenwood 8101d mono block amp putting out 400 watts rms at 2 ohms.  i have the crossover set to play everything below about 70 hz.  my problem is this...my bass is very choppy in songs that have bass lines that vary alot in one sound. for example, a bass line that goes from 40 hz steadily up to 150 hz then drps to 50 hz again, sounds like sh*t with my setup becuz i hear no sound from my sub at the areas above 100 hz, no matter how high i tunr my crossover.  this is becuz kicker solobarics have a frequency response that is only up to 100 hz.  so a bass line that is supposed to be one long boooom,...is played as boo-booooommm in my setup.. its pissin me off.  i have a box on the way from a store that has a 3 cubic ft chamber with a slot port in it.  do you think this will help my problem at all? im hoping it will slow down the waves a lil bit and maybe blend in the choppiness. any suggestions if this idea wont work? any help would be appreciated.  thnx!

need to post this ? on a different forum, you won't get the answer on this one. try the car audio forum.

you might want to look into getting different front and rear speakers. because the sub is doing what it should. most subs should be crossed over around 65-75Hz and the mid-bass driver should over lap that slope just a little and pick up where the sub is leaving off. a bigger box may help a little. more than likely tho it will allow it to play a bit deeper. i would try and add a pair of good 6" or a pair of 8" midbass drivers up front to help you out where the sub is lacking. in the systemi am designing right now for my car, i will have 2 sets of 6.5" in the front and one in crossed over at 150Hz and down and the other is playing from 50Hz on up. that way the bass blends a bit better with the rest of the system. a lot of companies out there sell a slim basket midbass driver that will fit a lot of places.