can any one help and give me the equations to calculate the box airspace and tuning on the box ... bcause i want to learn a very accurate way to design boxes like calculating them by pen and paper without using a software. PLEASE HELP

Didn't watch the whole vid, but randomly clicked to a point in the vid and the first thing I hear him talking about is port area per cubic foot. Since that is a bullshit method of port design and misinformation it makes me weary of anything he says in the video.

http://www.diysubwoofers.org/prt/

The links to the left give you the formulas to calculate port length, minimum port area, frequency response, etc

I would purchase a copy of the Loudspeaker Design Cookbook.

does anyone know how  http://highoutputenclosures.storenvy.com/ designs and calculate their boxes... they r top quality and i wanna learn how to design and calculate them myself

8th grade geometry should suffice