Well i would like to have a more Narrow passband. 25-50hz sounds good. I understand how to do ported box designs, but i wanted to kind of test out how i like 4th orders set ups. But i cant find any real clear ways to design a box. Thanks for your help. The sub im working with is a DC lvl 4 15" with lvl 5 soft parts. It it just as easy as finding out what the suggested sealed and ported volumes are and put them together. haha im sure its not but i dont know.. i Wanna learn! ha