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CHAPTER 5
In no case should a filter higher than 2
nd
order be used. The
additional phase shift introduced deteriorates the impulse
response and higher roll-off does not improve crossover
interaction. In fact, it is highly recommended that the
crossover/filter be set to emulate the low-cut LD-1A/LD-2
characteristics themselves, as shown in Table 5.4.
Table 5.4. LD-1 / LD-2 “Lo-Cut Filter” Parameters (160 Hz
HPF in the LD-3)
Type
Order
Pole
Frequency
Q
High Pass
2
nd
(-12 dB/oct) 162 Hz
0.82*
* If the DSP does not have variable Q for high-pass filters, the filter
should be set to “Butterworth” (Q
≈
0.7).
TIP:
All other filters on the LD-3 are parabolic
filters with minimal phase shift; most com-
mercially available DSP devices have no presets to
emulate the LD-3’s parabolic filters.
CAUTION:
If the loudspeakers are going
to be driven directly from the DSP, verify
that the outputs of the processor have the driving
capabilities to drive the total load presented by the
loudspeakers connected to it. Please refer to the
Audio Input section of “Chapter 3: Amplification and
Audio.”
NOTE:
When precise array design,
subwoofer integration, DSP and delay sys-
tems, and compensation for acoustical conditions
all come into play, measurement and correction
tools are a must. Meyer’s SIM audio analyzer sys-
tem; LD-1A/LD-2, LD-3 line drivers; CP-10 paramet-
ric equalizer; and the VX-1 program equalizer are
highly recommended.
