Specifications
188
Car Audio Reference Guide
Subwoofer Enclosure Calculations
Clarion offers an extensive line of high quality,
product specific subwoofer enclosures. Clarion
dealers will, on occasion, be called upon to cus-
tom build a subwoofer enclosure from scratch
to better maximise the space inside a vehicle,
provide room for additional speakers, integrate
an elaborate amp rack or to perform a completely
custom installed. The following instructions out-
line the steps required to design a custom-sized
subwoofer enclosure.
Step 1: Measurements
The first step is to take careful measurements of
the vehicle in which you want to build the enclo-
sure. You must measure the maximum width,
height and depth, taking into consideration the
ability to install the enclosure into the vehicle
through the trunk/hatch opening. Also consider
bracketry, seatbelt enclosure and other obstacles
in the trunk.
Example:
Trunk Width: 35.0 inches
Trunk Height: 14 Inches
Desired Max Depth: 11 Inches
The Maximum desired depth and/or the trunk
opening will determine just how big the enclosure
can be. You can always make it smaller.
Step 2: Rough Calculation
Now that you have some basic numbers, you
can calculate the maximum possible enclosure
volume. Clarion strongly suggests that 3/4" or
thicker MDF or good quality plywood be used for
all enclosures. In our example we will use 3/4"
material.
Example:
Take each dimension and subtract the wood
thickness:
Internal Width: 35.0 - (2 x 0.75) = 33.5
Internal Height: 14 - (2 x 0.75) = 12.5
Internal Depth: 11.0 - (2 x 0.75) = 9.5
Multiply these numbers together to come up
with an internal volume:
33.5 x 12.5 x 9.5 = 3978.125
Divide by 1728 to convert this measurement into
cubic feet:
3978.125 รท 1728 = 2.30 ft
3
This is the largest air volume (not including woof-
er, port or brace displacement you can use. You
can now select the subwoofers you want based
on this information.
Step 3: Subwoofer Selection
Clarion subwoofer spec sheets include several
popular and highly effective enclosure designs.
Using the volume calculated above, you can
choose any driver or combination of drivers you
want to occupy this space.
Example:
In our example, we have a maximum gross
volume of 2.30 cubic feet. Looking through the
Application Guide - we see that a few of our
options are:
The PXW1252 requires a net volume of 1.7
cubic feet in a ported enclosure.
Two PXW1252 woofers require a net volume of
1.6 cubic feet in a sealed enclosure
Two PXW1052 require a net volume of 2.0 cubic
feet in a ported enclosure.
Three PXW1052 subwoofers require a net vol-
ume of 1.5 cubic feet in a sealed enclosure.
One PXW1552 requires a net volume of 1.5
cubic feet in a sealed enclosure
We'll go with a pair of PXW1052 drivers in a
vented enclosure.
Step 4: Final Volume Calculations
Knowing the maximum width and height of
the enclosure, so we can modify the depth of
the enclosure to create the perfect net internal
volume.