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Figure 4.7. The LD-3 air attenuation compensating line driver
NOTE:
The LD-3 utilizes multiple-variable
atmospheric loss equations and pre-
calculated MAPP Online stored values to provide
frequency response correction quickly and efficiently
(up to 16 kHz at a resolution down to 1 dB). Its high-
quality, digitally-controlled analog filters provide
the best of both worlds: the low latency and wide
dynamic range of analog and the nimble, precise,
repeatable results of digital.
The LD-3 features high-quality high-pass and low-pass
filters to help integrate MILO and other M Series curvilinear
line arrays with Meyer Sound subwoofers. These filters,
along with the LD-3's dedicated sub section, will optimize
your MILO loudspeakers' headroom and reduce the area of
overlap with subwoofers, minimizing cancellations.
NOTE:
For more information on
recommended settings for the integration
of MILO arrays with Meyer Sound subwoofers, as
well as the LD-3's atmospheric and array correction
features, please refer to the LD-3 Operating
Instructions or visit www.meyersound.com.
Digital Signal Processors
Full-range signals may be applied to Meyer Sound's self-
powered loudspeakers because they have built-in active
crossover circuits; external crossovers and digital signal
processors (DSP) are optional and should be used very
carefully due to phase shifts that can cause cancellations.
If DSP is used, both MILO loudspeakers and subwoofers
should be fed from the same DSP in order to keep their
delay time the same. Otherwise you may experience phase
shift differences between the MILO loudspeakers and the
subwoofers. In addition, you should verify the delay time
between channels: some DSPs may develop channel-
to-channel delay errors when the DSP is near maximum
throughput, which becomes more likely as the number of
filters the DSP is using increases.
In no case should a filter higher than 2nd-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 are set to emulate the low-cut LD-1A/
LD-2 characteristics themselves, as shown in Table 4.1.
Table 4.1 LD-1 / LD-2 "Lo-Cut Filter" Parameters
Type
Order
High Pass
2
(-12 dB/oct)
nd
* If the DSP does not have variable Q for high-pass filters,
the filter should be set to "Butterworth" (Q ≈ .7).
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 on page 9 in this manual.
NOTE:
When precise array design,
subwoofer integration, DSP and delay
systems, and compensation for acoustical
conditions all come into play, measurement
and correction tools are a must. Meyer's SIM
measurement system, the CP-10 parametric
equalizer and the VX-1 program equalizer are highly
recommended.
MEYER SOUND MAPP ONLINE
MAPP Online (Figure 4.8) is a powerful, cross-platform,
Java-based application for accurately predicting the
coverage pattern, frequency response, impulse response,
and maximum SPL output of single or arrayed Meyer Sound
loudspeakers.
Figure 4.8: MAPP Online is an intuitive, powerful system design tool.
Residing on your computer, MAPP Online facilitates
configuring arrays of a wide variety of Meyer Sound
products and, optionally, defines the environment in which
they will operate, including air temperature, pressure, and
humidity, as well as the location and composition of walls.
CHAPTER 4
Pole
Q
Frequency
162 Hz
1.82*
®
21
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