does anybody have the formula to calculate the dimensions of a box? i just bought 2 12" power acoustik fubar subs (1800 watts). i have them in a dual bandpass box right now but they sound like shit and not that loud. i have a 3000 watt amp to. they say they need 1.2 cubic feet air space in a sealed box. what would the dimensions be for a box that size i could build? thanks