WinISD recommends a 3.2 cubic foot box with a 24 Hz tuning frequency for our vented enclosure. Using a four inch port we'll need a vent that is fifteen inches long. We must take this volume into account. The volume of a cylinder is pi*r^2*h, or (3.14)*(2)^2*15 = 188 cubic inches. Divide this by 1,728 to get cubic feet and we add 0.11 cubic feet to the enclosure. We'll achieve this by using 3/4 " MDF for the enclosure with external dimensions of 19.5" x 30" x 12.5". This will be a simple rectangular box. Modeling the enclosure we see that it has a 87 dB sensitivity and a -3dB (half power) frequency of 24 Hz (the tuning frequency). This box should give incredible amounts of output when it is combined with the 12dB/octave boost provided by most automobiles. This is to be expected with a box this large. In practice we would probably make the enclosure half this size, or similar to the size of the sealed enclosure.

Here is the layout of our subwoofer enclosure. We will need to cut the following pieces:

SIDE |
QUANTITY |
DIMENSION |

TOP/BOTTOM | 2 |
30" x 12.5" |

FRONT/BACK | 2 |
30" x 18" |

SIDES | 2 |
18" x 12.5" |

You should also check out * Advanced Enclosure Design and Fabrication*. It covers designing enclosures using free computer software, maximizing the output of a subwoofer system, building the box like a pro and testing the output using inexpensive equipment. Click here.

**Next Page ---> Plan #3 - Bandpass Subwoofer Enclosure**