Here are the specs from Alpine

General

* • Diaphragm Material : Aluminum Coated Poly and Kevlar Reinforced Pulp
* • Displacement Front Mounted : 0.067 cu.ft.
* • Displacement Rear Mounted : 0.086 cu.ft.
* • Frame Design : Deep Draw with Vented Leg/Spider Plateau, Integrated Terminal landing
* • Gasket Design : Injection Moulded Hidden Screw Design with Front/Rear Sealing
* • Magnetic Weight : 50oz.
* • Motor Structure Configuration and Pole Geometry : Extended Dual Flare Pole Vent, Compound Radius Curve( Patent #6, 639, 993)
* • Mounting Depth (top mount) : 153mm (6.1")
* • Mounting Diameter (top mount) : 227mm (9")
* • Optimum Sealed Box Volume : 1.0 cu. ft.
* • Optimum Vented Box Volume : 1.2 cu.ft,
* • Recommended Box Types : Sealed/Vented/Bandpass
* • Recommended Sealed Box Volume : 0.65 - 1.5 cu. ft.
* • Spider Material : Nomex®
* • Surround Design and Material : High Excursion Tapered Half-Roll, Injection Moulded Santoprene®
* • Terminal Type : Heavy Duty 8ga. Push with Housing, Banana Plug Jumper
* • Vented Box Volume Range, Vent Diameter/Length : 1.0-1.75 cu.ft., 3" ID x 9" Long

So for a sealed box thats square you could build it 13.5" x 13.5" x 13.5" outside dimensions and that would be 1 cu. ft. inside volume. and for vented they say 1.2 cu. ft. so 14.5" x 14.5" x 14.5" outside dimensins will give you the desired volume needed and a port 3" ID x 9" long.

I wouldn`t try a bandpass encloser if your not familiar with box building, so I didnt give you any specs for one.

Hope this helps
Garett
Hope this helps