5
construction
materials and assembly
Regardless of the type of enclosure design you choose, it must be solidly constructed and be free
of any air leaks. Make the panels from MDF or Baltic birch plywood at least ¾” (20mm) thick. All
joints should be liberally glued with carpenter’s glue or construction adhesive. Do not depend on
hot-glue, or screws, for joint strength. If screws or staples are used, use them only to hold the
panels in place while the glue dries.
It is a myth that vented enclosures do not need to be as airtight as sealed enclosures. Due to the
reactive effect of the tuning, the internal pressures at some frequencies are greater in vented or
bandpass enclosures than in sealed enclosures. Make a point to make all enclosure types as air-
tight as possible.
Fiber-reinforced resin may also be used to form difficult shapes. When designing an enclosure this
way, try to avoid large flat panels which may easily flex and rattle under pressure.
The woofer should be sealed to the enclosure with foam gasket material or RTV silicone.
damping material
The internal walls of a vented enclosure, or the vented side of a bandpass enclosure, should be
lined with acoustic damping material in order to reduce sonic reflections. If you are constructing a
wood enclosure without any see-through sides, common polyester fiberfill batting or fiberglass,
approximately 1” thick, is good for this purpose. There are a number of commercially available
damping materials available if you need something cosmetically suitable for use in an enclosure
with see-through sides. A sealed enclosure, or the sealed portion of a bandpass enclosure, should
be completely filled with fiberglass or polyester fiberfill with a density of approximately 16oz. of
material for each 1 cu.ft. of enclosure volume. If you choose to use a sealed enclosure without
damping material, add 20% to the enclosure volume recommended on the specification sheet.
vents
Although the vent specifications in the enclosure recommendations are round, they may be any
shape which lends itself to your installation. To adjust vent dimensions from those we recommend,
maintain the same
ratio
of vent
area
to vent
length.
Be careful when you consider changes
however.
If you increase vent area, the length must increase to maintain the same ratio. This may
make the vent unreasonably long. If you decrease vent length, the area will need to be decreased,
possibly resulting in excessive wind noise from the vent. To keep vent noise to a minimum, radius
all of the sharp edges of the vent.
wiring
A-series
Each of the terminals used on the speakers is marked on the fiber panel adjacent to the terminal
indicating it’s polarity. These terminals accept standard .250” female quick-disconnects. Alter-
nately, wires may be soldered directly to the terminals.
Each voice coil has a nominal impedance of 4-Ohms. When using two subwoofers with two ampli-
fier channels, it is best to wire each woofer to an individual channel. When using more than one
woofer per channel, they may be wired in series or parallel, as shown on the next page, depending
on the impedance drive capabilities of your amplifier.
Summary of Contents for 310rs
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