CALCULATING
ENCLOSURE
VOLUME
First, measure out the area you're interested
in
placing the subwoofer
enclosure. Use agood-quality measuring tape to determine the MAXIMUM
height, width, and depth
of
your area. Height
is
the measurement up-and-
down, width
is
the measurement from side-to side, and depth
is
the
measurement back-to-front.
Calculating the correct box size
is
easy if you just remember afew simple
formulas and calculations. The key to calculating internal box dimensions
is
a
basic understanding
of
volume: Cubic volume
is
derived by multiplying each
of
an
object's dimensions (height, width, depth) by each other.
i12"
~~-1;:'~
12X12X24=3456
3456
+1728=2.0
For example:
If
you measure the
internal dimensions
of
arectangular object
(like asubwoofer box) and its internal
height
is
12", its width
is
24", its depth
is
12", and then multiply those dimensions
together (12" X24" X12"), then you come
up with avolume
of
3,456 cubic inches.
Divide this number by 1728
(l
cubic foot)
and the total
is
the internal cubic volume
of
the box, which in this case
is
2.0 cubic feet.
Enclosure volumes are never listed in cubic inches, so it is necessary
to
convert from cubic inches to cubic feet. (A cubic foot is no more than
12"
X
12"
X
12"
or 1,728 cubic inches.) So, to convert from cubic inches to
cubic feet, simply divide the volume
in
cubic inches by 1,728.
Round to Square Port Conversions:
As the use
of
the square port has become even more popular, this
is
agood
time to explain how to convert round ports into square/rectangular ports. For
example:
If
asubwoofer calls for a
6"
port that is
13"
long, then take
1/
2
of
the
port size,
in
this case it would be
3.
Multiple this number by itself, so 3x3=9.
Now multiply the 9 x PIE (3.14) and this
is
the total area
of
the square port
opening or 28.26 square inches
of
opening.
If
you speaker calls for more than one port, multiply the number
of
ports
by the number you calculated to get the combined calculated port area needed.
If
you notice you have just use the area
of
acircle formula (Pie x r (squared).
As for how long the square port should be, the length stays the same
as
the
round port. The reason
is
because the length
of
the port determines the tuning
of
the port and the length
is
not effect by the conversion from round to square
ports.
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