6. Calculating Enclosure Dimensions
There are several important equations required to facilitate the calculation of enclosure
dimensions. You will ultimately want to alter then dimensions for your enclosure to
maximise the usable trunk space in your vehicle. The following example will show
the general procedure to calculate the dimensions for an enclosure suitable for 2
SRW1251/SRW1252 subwoofers.
The calculations below will provide the enclosure depth, allowing you to construct your
enclosure and enjoy bass, the way it was meant to be heard.
What you need to know: Example:
Maximum Trunk Width 35 inches
Maximum Trunk Height 15 inches
Net Enclosure Volume 2.5 cubic feet
Material Thickness 0.75 inches
Driver Displacement 0.06 cubic feet
Port Dimensions 4” x 7.5” long
Step 1: Measure the trunk width and height. Take note of seat belt mechanisms, strut
tower protrusions and trunk opening size when measuring.
Eg: 35” wide by 15” tall
Step 2: Calculate the gross enclosure volume. This includes the net enclosure volume,
plus the displacement of the drivers, port(s) and any bracing. There is no bracing
being used in this example, however Clarion recommends an enclosure of this size be
properly braced.
Eg: 2.5 ft3 net volume, 0.06 ft3 per speaker, 0.049 ft3 port.
Gross Volume: 2.5 + 0.06 + 0.06 + 0.049 = 2.665 ft3 or 4605.12 cubic inches.
Step 3: after subtracting the material thickness from the maximum width and maximum
height, we can calculate the depth of the enclosure.
Eg: 4605.12 ÷ ((35-0.75-0.75) x (15-0.75-0.75) = 10.18 inches.
Step 4: Add the material thickness to the inside depth calculation and you have the
outside dimensions of you enclosure.
Eg: 10.18 + 0.75 + 0.75 = 11.68 inches.
Width = 35” Height = 15” Depth = 11.68”
Step 5: You can now cut and assemble the panels for your enclosure. Make sure all
joints are perfectly sealed and there are no air leaks anywhere. If you choose not to
wrap the enclosure in carpet, use foam gaskets when installing the woofers to ensure
an air-tight seal against bare wood.
SFW/SRW/SW
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