Hello all. I apologize for the background info but it paints a picture. Thank you for any advice and help!\nBackground\nI purchased a 12" subwoofer off a site called DIYCable that is no longer around. I bought it many years ago and I honestly can't remember what model it was. The box it self says "Exodus Shiva-X" with a part number XJ-12.\n\nWhen I google "Exodus Shiva XJ-12" the best I can come up with is that this sub was a limited run of a 12" sub that the build house got wrong, changing the intended use\/specs slightly. The company, Exodus Audio, sold these off at a discount rather than sending them back to the build house.\n\nMy issue is...I'm only assuming this is the sub in the box because that is what the box it was shipped in said.\n\nQuestions:\n1. So I'm reading that 3.5cu ft box is what I should build. Am I right that this would be 18.22" * 18.22" * 18.22"? Should it be ported or sealed?\n2. I see parts express has a 250 plate amplifier that has DSP which would be cool. As far as amplification goes, would 250 watts be enough?\n3. Is there anything I'm missing besides the box and the plate amplifier?\n\n\n\n\n\nMessage I found when googling:\n\n"There are also XJ-12 12" models available!\nThey have a highish Q of about .9 (system Q, not driver Qts) but in the car that would give you a lot of thump, essentially flat anechoic to 40Hz and with cabin gain that would be insane. Same motor, slightly different parameters. They also look good in 3.5ft^3 tuned to about 20Hz. They would be a good HT sub in that type of enclosure being essentially flat to 30Hz (anechoic) and fall off fairly quick below that point. In-room measurements as a typical company would post they would be good to under 20Hz flat in-room with some good HT excitement in the 30-60hz range.\nParameters on the XJ-12 with VCs in parallel (dual 8s).\nRe: 3.95\nfs: 31Hz\nQms: 4.35\nQes: .67\nQts: .58\nmms: 114g\ncms: .233 mm\/N\nVas: 83L\nBL: 11.4\nEff: 87.7db\/1W\/1M\nxmax: 26-27mm one way\nPmax: Lets say 600W which is conservative. If you thermally fry the thing your doing something very stupid."