6
Building an Enclosure
To work properly, the walls of the enclosure must be rigid and not flex
when subjected to the high pressures generated by the speaker's operation.
For optimum performance, we recommend using 3/4" MDF (Medium
Density Fiberboard) and internal bracing. The enclosure should be glued
together and secured with nails or screws. MDF is porous; therefore, it is
suggested to also seal the outside walls with polyurethane.
Calculating Volume
Calculating volume is merely a matter of measuring the dimensions in
inches and using the formula:
1728"/(cu in/cu ft)
Height” x Width” x Depth”
Box Volume=
(cubic feet)
If two facing sides are of uneven length, add them together and divide by
two to take the average. Using this number will give you the volume with-
out the necessity of calculating the box in sections and adding the sections
together. The thickness of the baffle material reduces the internal volume
so this must be subtracted from the outside dimensions to determine the
internal volume. The speaker itself also reduces the internal volume. The
amount of air displaced by each model is listed on the specification sheet
and should also be subtracted from the gross volume calculation.
Subwoofer Crossovers
There are two operational types of crossovers, passive and active. Passive
crossovers (coils or inductors) are placed on the speaker leads between the
amplifier and speaker. An active crossover is an electronic filter which sep-
arates the audio signal fed to different amplifiers. For optimum subwoofer
performance, we recommend using an active 80-100Hz low-pass
crossover at 12dB/octave.
