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CHAPTER 5
CAUTION:
When daisy-chaining, make sure
that the source equipment can drive the total
load of the paralleled array. (See “Chapter 3: Amplifi-
cation and Audio” on page 9.)
Adding an LD-1A/LD-2 Line Driver
Driving 700-HP subwoofers and Meyer Sound loudspeak-
ers with the same signal from different outputs using a line
driver allows adjustments to the gain of each sub-system,
and could be used effectively to compensate for the ratio of
loudspeakers or acoustical conditions. If the gains are ad-
justed to the same level, the combined response is identical
to a daisy-chained configuration.
Using the LD-1A/LD-2’s Lo-Cut Filter
Using the Lo-Cut filter of the LD-1A or LD-2 (Figures 5.1
and 5.2, respectively) optimizes the full-range loudspeaker
headroom and reduces the area of overlap; the full-range
loudspeakers in the system receive their signal following
a Lo-Cut (high-pass) filter, while the 700-HP subwoofers
apply their normal internal crossover frequencies to a full-
range signal. This configuration results in a smooth frequen-
cy response through crossover and reduces the overlap
frequency range between the speakers. However, the use of
external filters – like the Lo-Cut in the LD-1A/LD-2 – is op-
tional, and should be used very carefully to minimize phase
shifts that can cause cancellations in the overlap area.
NOTE:
When driving Concert or UltraSer-
ies loudspeakers from the Mid-Hi output
of the LD-1A or LD-2 line driver, with the Lo-Cut
filter engaged and the 700-HP subwoofers in their
full-range configuration, a change of polarity on the
Sub Output might be needed due to the phase shift
caused by the high-pass filter at overlapping fre-
quencies. Placing the subwoofers more than 4 feet
apart may require reversing the polarities once again
to compensate for the delay propagation. If they are
separated by a greater distance — or delay must
be used between them — a measurement system
such as the SIM audio analyzer should be used to
determine the correct delay and polarity.
Figure 5.1. The LD-1A line driver
Figure 5.2. The LD-2 line driver
USING THE 700-HP WITH M SERIES LOUD-
SPEAKERS
The 700-HP integrates easily with M Series linear and cur-
vilinear arrays. The 700-HP can be flown using the optional
MRK-700 rigging kit and MTG-700 top grid in a straight
array next to an M Series array, or ground stacked.
NOTE:
There is no polarity switch on the
700-HP and it is wired pin 2 “hot” (positive
acoustic pressure when a positive pulse is applied
to pin 2), making its integration when coplanar
— and in close-proximity — easier when flown or
ground stacked with M Series arrays.
700-HP subwoofers should be kept as close as possible to
M Series loudspeakers to avoid phase errors and cancella-
tion in some seating locations. Ideally, the arrays should not
be separated by more than 3 feet.
NOTE:
If the 700-HP subwoofers are placed
more than 4 feet away from the M Series
array, you may need to set the 700-HP and the M
Series loudspeakers to opposite polarities.
Adding an LD-3 Compensating Line Driver
Full-range signals may be applied to Meyer Sound’s self-
powered loudspeakers and subwoofers because they have
built-in active crossovers. However, the use of external
filters — like the ones in the LD-3 compensating line driver
(Figure 5.3) — is highly recommended, especially in me-
dium-to-large systems.
Figure 5.3. The LD-3 compensating line driver
