need help on my first 4th order

[caraudiolove]

i need help on my first 4th order is their any calculations i need to know and if their is let me know please thank you and i could use a box design that would help

31"W,30"-40"L,15"h Thank you

2 12" obsidian audio

[bassface]

There is a pretty decent thread under subwoofers, all about 4th orders, you should read that thread first to get an idea of how to go about building it.