Operating instructions

4
Operating Instructions Addendum: MILO 60
USING SUBWOOFERS WITH THE MILO 60
A MILO 60 system (or combined MILO 60/MILO/MILO 120
system) will provide full bandwidth frequency response
down to 60 Hz. The height of the array (number of cabinets)
will determine the total SPL available and how much low
frequency energy can be provided, proportional to the
upper-frequency spectrum.
If higher SPL is necessary, or the program content requires
additional low-frequency energy (e.g., the reinforcement
of popular music), then subwoofers should be used to
augment your MILO curvilinear array.
Meyer Sound subwoofers, such as the M3D-Sub and
700-HP, can achieve frequency response down in the 30
Hz range, extending the system response appreciably and
increasing the acoustic power of the system in the lowest
frequencies. In addition, the use of high-pass filters to drive
a MILO system with subwoofers increases the headroom of
the array in the lowest end of its usable spectrum.
The ideal ratio of MILO loudspeakers to subwoofers
depends on the configuration of the array and the frequency
content of the signal being reproduced by the system.
For most applications, two MILO loudspeakers for each
subwoofer yields good results in frequency response and
headroom.
NOTE: The limit LEDs indicate when the safe
power level is exceeded. If the subwoofers
used in the system begin to limit before reaching the
required SPL at low frequencies, consider adding
more subwoofers to satisfy the SPL requirements
without exposing the drivers to excessive heat and/
or excursion.
Using the LD-3 compensating line driver’s filters helps
to easily integrate and optimize your MILO arrays with
subwoofers. The use of high-pass filters augments
array headroom by removing lower frequencies near the
unit’s lower operating range, while low-pass filters can
remove unwanted mid-low frequencies reproduced by
the subwoofers. The use of these filters reduces the area
of overlap and minimizes the interaction and possible
cancellations between subsystems.
NOTE: 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 line driver — is optional,
and should be used very carefully to minimize phase
shifts that can cause cancellations.
MILO 60 with the M3D-Sub
The M3D-Sub directional subwoofer adds substantial low-
frequency headroom to MILO curvilinear arrays, extending
the system frequency response to 30 Hz.
The M3D-Sub has advantages over other subwoofers due
to its unique low-frequency directional control and its ability
to be vertically arrayed with MILO since they share the
same width.
NOTE: For most applications, you want to
keep low frequencies from being produced
behind the array to reduce or eliminate the low
frequency reverberant noise traditionally associated
with large-scale, full-range loudspeaker arrays. The
M3D-Sub’s award-winning and patent-pending
cardioid directional pattern provides maximum low-
frequency attenuation from 6 to 12 meters behind
the cabinet (-20 dB at 8 meters).
Table 1 shows how you can integrate MILO (or combined
MILO 60/MILO/MILO 120) arrays with the M3D-Sub
subwoofer using the LD-3 line driver’s filtering capabilities
to fine-tune the system. All the data in Table 1 is based on
system designs with a 2:1 ratio and in a close-proximity,
coplanar orientation.
When loudspeakers and subwoofers are physically
separated by more than 4 feet — or delay must be used
between them — a measurement system such as the SIM
audio analyzer (covered in Chapter 5 of the
MILO Operating
Instructions) should be used to determine the correct delay
and polarity.
Table 1. MILO 60/MILO/MILO 120 and M3D-Sub
HPF LPF
ø Reverse
Switch
Result
80 80 Engaged Flat response
80 Off Engaged Flat response
160 Off Engaged Very flat response
Off Off Off Boost in the 80 Hz region