I am planning on building my own sub, a 24" cubic enclosure with an AV15 and two 18" PR's is what i am after. Is there a better solution for the price? A 2ft box is as big as i would like to go. Right now i have an SVS 20-39 with Samson S-700 amplifier. I think 700 watts will suffice for the new sub. What improvements can i expect over the SVS in my 12x18.5x8 room? Construction details please?