BOX CONSTRUCTION (SEALED OR VENTED):
The material used for enclosure walls should be
solid, dense and free of voids or warps. Your enclosure should be made ¾” or 19mm material, Finland
or Baltic birch type plywood is recommended where the enclosure will be transported frequently. High-
density fiberboard - MDF (not chip board) can be used on permanently installed systems. Minimum of 1”
(25mm) or double ¾” (1-1/2”) baffle is recommended on high-powered SPL applications. Corners must be
strong and air tight and should not have any air leaks or openings. Joints should be properly filled with glue
that will not crack under high stress or impact. If the integrity of the glue seal can’t be determined, hot
glue or RTV caulking should be used to seal all seams. Fiber reinforced resin may also be used to form any
difficult shapes. However avoid making large panels with resin to eliminate any chances of box flexing,
cracking or ratting under high pressure. Bracing made of 2 x 2” or 2 x 4” should be liberally applied either
inside or outside the cabinet, depending on whether the cabinet is to be permanently installed or portable.
This principle applies to any walls of the enclosure spanning more than 18” long. Any braces should also
be liberally glued or screwed down on edge. Edge-wise drilled, and countersunk holes through the braces
can be used for #10-2 Flathead wood screws to avoid the use of more expensive lag bolts. The majority
of strength from an enclosure comes from the glue. When using screws be sure to pre-drill holes to avoid
splitting the wood.
WARNING! The use of silicone rubber to seal in a speaker will void the Warranty! If any sealing
is needed in addition to the speaker’s gasket, use caulking cord or vinyl weather strip.
SUBWOOFER CROSSOVER SETTING
Your PowerBass subwoofers will perform best if they are used in conjuction with a subwoofer crossover of
some kind. Using a crossover will remove unwanted high frequencies and allow them to concentrate only
on bass. The two most common types of crossovers are “passive” or “active” (electronic crossovers are
active). Many amplifiers have a built in Low Pass (LPF) electronic crossover circuit. For optimum subwoofer
performance we recommend an initial electronic crossover setting between 80-100Hz and then tuning
the bass to your liking.
9
