When the proper room volume has been determined, the designer then can go to the following
table and pick the required quantity of subwoofer modules that will ensure the needed acoustical
power output:
d
Number of 2242
-poww
A---w
%
dM
1
4
800
16
2
6 1600 64
4
12
3200
192
8
16
6400 !ioo
Table 3: Nominal Efficiency and Acoustical Power Output of
Multiple
Subwoofer Systems
.-.
The designer should choose the next higher increment if the power requirement, based on
room volume, falls between two increments in the above table.
Figure 22 shows an exploded view of the JBL 46458 subwoofer module. Each subwoofer
module should be driven with its own amplifier capable of producing up to 800 continuous watts of
sine wave power into a rated impedance of 8 ohms. A pair of subwoofer modules can be driven by a
single JBL model
MPX1200
amplifier, which is capable of producing continuous sine wave power of
606
watts into each of two
8-ohm
loads.
-
d
4
Actual efficiency of combined units will
vary
depending on the spacing among them.
Numbers given here are
reasonable estimates.
5
Acoustical
output
power has been derated, considering the high-level,
longterm
effects of dynamii compression
under steady state subwoofer conditions.
Peak values may be 3
dB
higher,
depending on nature of program.
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