Rockford Fosgate Punch P38D2 Installation Et Fonctionnement page 7

B E
UILDING AN NCLOSURE
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.
CALCULATING VOLUME
Calculating volume is merely a matter of measuring the dimensions in inches and using the formula:
Box Volume = Height " x Width" x Depth"
(cubic feet) 1728 cu. in./cu. ft.
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 without 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.
S C
UBWOOFER ROSSOVERS
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 separates the audio signal fed to different amplifiers. For optimum subwoofer performance, we
recommend using an active 80-100Hz low-pass crossover at 12dB/octave.
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