I used this site as my basis
http://www.hometheaterhifi.com/volum...tythumper.html
I used this paper as a basis for building my subwoofer. I didn't use there sizes but did use the design using double baffle for both rear and front. I sized my at 16x16x16 using a sealed enclosure. I had a old integrated amp so I used it to power the sub using the subout on my receiver to the tape in on the integrated amp. I use my receivers crossover to limit the frequency going to the sub. I used the Dayton Titanic MKII driver from parts express, MDF for the box, liquid nails and finishing nails to seal and hold the box together, then painted it with a black enamel. Also bought some chrome feet from PE along with speaker cloth. Used MDF for the grill. I have to say I am happy with the results and am glad I built it. Total cost with all parts, wood, etc. was about $254.00. Make sure you use one of those box calculators to figure out the internal dimensions of the box. I used a Q of .707