How much subwoofer fill is enough? can there be to much? is it better without? The box is 24.5” tall ,19.5” deep, 19” wide. It has one port in the corner that is 15" long and 4" wide . The area inside is about 5.11 cubic feet or 144.87 liters. I bought a Dayton 15" titanic MK III. Currently I have the box filled with enough room for the speaker to fit in.