17
CHAPTER 5
NOTE:
When driving Concert or UltraSeries
loudspeakers from the Mid-Hi output of
the LD-1A or LD-2 line driver, with the Lo-Cut
filter engaged and the 600-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
frequencies. 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
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
medium-to-large systems.
Figure 5.3. The LD-3 compensating line driver
Using the LD-3’s filters helps to easily integrate and opti-
mize a MICA or other M Series array with the 600-HP sub-
woofers. The use of high-pass filters (HPF) augments aray
headroom by removing lower frequencies near the array
loudspeaker’s lower operating range, while low-pass filters
(LPF) can remove unwanted mid-low frequencies repro-
duced by the stack of subwoofers. The use of these filters
reduces the area of overlap and minimizes the interaction
and possible cancellations between subsystems, usually
resulting in highly desirable behavior, such as very flat fre-
quency response.
NOTE:
The use of external filters — like the
ones in the LD-3 — should be used very
carefully to minimize phase shifts that can cause
cancellations.
NOTE:
When driving the system using the
LD-3 with the filters engaged, a change of
polarity on the Sub Output might be needed due to
the phase shift caused by the filters at overlapping
frequencies. 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 sys-
tem such as the SIM audio analyzer should be used
to determine the correct delay and polarity.
Using the Galileo 616 Loudspeaker Management
System
The Galileo 616 loudspeaker management system (Figure
5.4) is a combined hardware and software solution, offering
six inputs and 16 outputs. Along with the Compass™ soft-
ware, the matrix structure of Galileo allows any combination
of inputs to be assigned to any combination of outputs, and
provides the ability to individually tailor the delay, level, and
equalization of each of these inputs and outputs.
Figure 5.4.
Galileo 616 loudspeaker management system
When used with the 600-HP subwoofer, Galileo offers a
sophisticated means of integrating the entire loudspeaker
system. Low-pass filters may be applied to the signal
source going to the subwoofers, and multiple sources can
be summed to that output. Galileo can be directly con-
nected with the SIM 3 audio analyzer system, permitting the
entire system to be optimized and measured.
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 Meyer Sound loudspeakers and 600-
HP subwoofers should be fed from the DSP in order to keep
their delay time the same. Otherwise, you may experience