Meyer Sound M1D - Manual (Page 19)

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CHAPTER 4
The M1D loudspeaker provides full bandwidth frequency
response down to 60 Hz. However, if the application or the
program content requires additional low-frequency energy
(e.g., clubs and popular music reinforcement), the M1D-Sub
loudspeaker is naturally the best way to augment your M1D
system. The M1D-Sub loudspeaker can achieve frequency
response down to 32 Hz, extending system response ap-
preciably and increasing the acoustic power of a system in
the lowest frequencies.
In addition, the use of high-pass filters to drive an M1D
system with the M1D-Sub loudspeaker flattens overall fre-
quency response and slightly increases M1D headroom in
the lowest end of its usable spectrum.
The ideal ratio of M1D to M1D-Sub loudspeakers depends
on the configuration of the system, the application, and the
frequency content of the signal being reproduced. For most
applications, two M1D loudspeakers for each M1D-Sub
loudspeaker yields good results in frequency response and
headroom.
NOTE: The M1D-Sub loudspeaker’s limit
LEDs indicate when its safe power level is
exceeded. If the M1D-Sub loudspeakers used in a
system begin to limit before reaching the required
SPL at low frequencies, you may need to add more
M1D-Sub loudspeakers to satisfy the SPL require-
ments without exposing the drivers to excessive
heat and/or excursion.
The M1D and M1D-Sub loudspeakers can accommodate
three basic connection options.
DAISY-CHAINED
When M1Ds and M1D-Sub loudspeakers are daisy-chained
using the loop feature on the Audio Input panel, the result
will have a fairly flat frequency response. However, at a ratio
of two M1D loudspeakers to each subwoofer, the response
will have a small rise in the 80 to 150 Hz range where the
frequency response of the M1D and M1D-Sub loudspeak-
ers overlap.
! CAUTION: Always ensure that the last device
in the chain of source equipment can drive
the total load of the paralleled system.
NOTE: When both M1D and M1D-Sub loud-
speakers are used in their full-range configu-
ration (e.g., looped audio or the same audio feed),
their polarities should be kept the same if they are
co-planar or near each other. If they are separated
– or delay must be used between them – a measure-
ment system such as Meyer Sound's SIM® audio
analyzer should be used to determine the correct
delay and polarity.
ADDING A LINE DRIVER
Driving an M1D and M1D-Sub system with the same signal
from different outputs using a line driver allows adjustments
to the gain and polarity of each sub-system, and could be
used effectively to compensate for the ratio of loudspeak-
ers or acoustical conditions. If the gains are adjusted to the
same level, the combined response is identical to a daisy-
chain configuration with a rise in level on the overlapping
range.
NOTE: When driving M1D loudspeakers from
the Mid-Hi output of the LD-1A, LD-2 or LD-3
line driver, with M1D-Sub loudspeakers in their Sub
out full-range configuration, their polarities should
be kept the same if they are co-planar or near each
other.
If your M1D or M1D-Sub loudspeakers are separat-
ed – or delay must be used between them – a mea-
surement system such as the SIM audio analyzer
should be used to determine the correct delay and
polarity to optimize their phase relationship through
crossover.
Engaging the Lo-Cut Filter
Using the LD-1A, LD-2 or LD-3 driver’s Lo-Cut filter (the
160 Hz HPF position on the LD-3) can produce a system
(in close proximity and co-planar) with very flat frequency
response and a minimal area of overlap. The M1Ds in the
system receive their signal following a high-pass filter, while
the M1D-Sub loudspeakers apply their normal internal
crossover frequencies to a full-range signal.
CHAPTER 4: USING THE M1D WITH THE M1D-SUB