Figures 1, 2, and 3 are example frequency
attenuation curves for three different temperatures with a
fixed distance of 100 meters, at seven values for relative
humidity. Depending on the atmospheric conditions and the distance
the array is throwing, the number of possible correction combinations
is staggering – and achievable with the LD-3.
Figure 1
Air absorption for 10 degrees C at 100 meters
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Figure 2
Air absorption for 20 degrees C at 100 meters
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Figure 3
Air absorption for 30 degrees C at 100 meters
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In addition to weather correction, the LD-3’s unique ability
to compensate for low to mid-low frequency build-up allows you
to fine-tune each channel driving an M Series array. Set the
type of loudspeaker you’re using and the number of cabinets
in the array, and the LD-3's stored presets do the rest for you.
Figure 4 is an example of a correction made on a MILO array with eight loudspeakers.
By applying this correction to the array the result is an incredibly flat
array system response across a wide range of frequencies.
Figure 4
Correction needed shown with eight MILO loudspeakers at 35 meters
Each of the LD-3’s two channels consists of a master input
section, a dedicated subwoofer output, and three outputs to control
the array. Three sends and four returns provide the control you
need, via insert switches, to route the signal and incorporate
additional signal processing, such as parametric equalization.
The master input section provides individual channel gain adjustment
from –12 to +6 dB, mute, signal/clip/mute indicators, and
a switchable high-pass filter (0, 80, or 160 Hz) for boundary
correction or optimizing crossover to subwoofers. Master environmental
controls include temperature (0° to 45° C), altitude
(switchable in three ranges: 0-800, 800-2200, and 2200+ m) and
relative humidity (10 to 100%).
Individual outputs provide gain trim from -6 to +6 dB (-6 to
-3 and +3 to +6 settings not recommended to preserve array behavior),
signal/clip/mute indicators, send/return insert switches, and
distance controls to define the throw from each sound system
branch to its audience coverage area up to 150 meters (492 feet).
The LD-3’s dedicated subwoofer control sections feature
polarity switches, gain trim from –6 to +6 dB, mute, signal/clip/mute
indicators, and send/return insert switches.
In addition to its sophisticated environmental and array control
functions, the LD-3 integrates different types of Meyer self-powered
speakers into a full-range main system, while maintaining signal
integrity for long cable paths.
The LD-3 occupies two standard 19-inch relay rack spaces. Flash
memory for future expansion is built in, and all input and outputs
are electronically balanced and utilize XLR (A-3) type connectors.
The AC inlet is an IEC standard male connector, protected with a
250 mA 250 V fuse, and switchable in the ranges of 105 to 125 V
AC and 210 to 250 V AC.
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