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SB Acoustics SB12PAC25-4 4″ Aluminum Cone Woofer

SB12PAC25-4 PDF specification sheet link

Vented reinforced plastic chassis
Anodised aluminium cone
Low damping rubber surround
Large vented motor system
Long stroke linear suspension
Light weight CCAW voice coil
Non-conducting fibreglass coil former
Non-resonant long life lead wires

A sealed box of 0.05 to 0.1 cubic feet should give you a 3dB down point of about 140Hz.  

A vented box of 0.1 cubic feet with a 1″ diameter vent by 4″ long will give you an F3 of about 70Hz.

A vented box of 0.2 cubic feet with a 1.5″ diameter vent by 4.25″ long will give you an F3 of about 59Hz

1 cubic foot equals 28.3 liters