Kicker CompVR C8VR Manual page 4

Vented Box Mounting
Almost as easy to build as the sealed box, the vented or ported enclosure can
give you more output at certain bass frequencies. Although this design has an
output advantage at some frequencies it also has a sharper rolloff characteristic
which will only affect the lowest of bass frequencies. Overall a correctly designed
vented enclosure will have some "free" output provided by the port itself.
One major disadvantage to the vented design is the "unloading" of the woofer
at very low frequencies. At a frequency 1/2-octave below the tuning frequency
of the enclosure the woofer acts like it has no box to work in and can go to full
excursion. This will be harmful to the woofer's mechanical integrity. It is there-
fore very important to stay with the recommended designs.
Since the peak pressure inside a vented enclosure can actually be higher than
that of a sealed box, the same precautions must be taken to assure that the
enclosure is rigid and sealed around all the joints.
Recommended vented enclosure volume ranges are .8-1.2cf for the C8, 1.25-
1.75 cf for the C10, 1.75-2.25 cf for the C12, and 3.0-4.0 cf for the C15. As with
the sealed boxes, as enclosure volume increases the response shifts from high
impact to a smoother and more extended bass sound.
Below are specifications for a simple compact vented box for each sub.
Compact Enclosure
Model
CompVR 8
Power Handling = 75W
CompVR 10
Power Handling = 150
CompVR 12
Port 2-1/2 x 12-1/2 x 20"
Power Handling = 150
CompVR 15
Port 2-3/4 x 15-1/2 x 25-3/4"
Power Handling = 500
CompVR 18
Port 3 x 18 x 24-1/4"
Power Handling = 500
4
(Minimum) Vented
Volume
.8 cu.ft + port
port 1-1/2 x 8 x 20"
1.25 cu.ft. + port
Port 2 x 10-1/2 x 20"
1.75 cu.ft. + port
3 cu.ft. + port
4.0 cu. . ft. . + port
SPL/Deep Bass
(Maximum) Vented
Volume
1.20 cu.ft. + port
port 2 x 8 x 18-3/8"
Power Handling = 75W
1.75 cu.ft. + port
Port 2-1/2 x 10-1/2 x 20"
Power Handling = 150
2.25 cu.ft. + port
Port 3 x 12-1/2 x 20-1/2"
Power Handling = 150
5 cu.ft. + port
Port 3 x 15-1/2 x 22"
Power Handling = 500
6 cu. . ft. . + port
Port 3 x 18 x 20-3/4"
Power Handling = 500