bro, in order to compute for a box, you need the thiele small parameters... and then base the box off of those figures. Usually this is done through various box design software.
Ang ubang mga box design software naa nay built in parameters for known speakers. so igo nalang ka magpili and hopefully naa siya sa database sa speakers...
Ang pinaka pait ang pag kuha sa thiele/small parameters... for those looking for a nose bleed, go here...
Thiele/Small - Wikipedia, the free encyclopedia...
If moadto ka sa EB bro, I can teach you a technique that can make you create a box that will meet your needs. mas sayon istorya kaysa i-explain. It's a simple way to solve your problem but it's subjective and not objective (subjective being a lot fo jdugement involved as opposed to using software na medyo ang guesswork nabuhat na)...