Design Guide - 5
Selecting Loudspeaker Models, Modules and Beam Patterns
Choosing Between 1, 2 or 3 Modules
When choosing the number of modules of an array, there are many elements to consider.
Max SPL, Throw Distance and Beam Control of Low-Frequency Content
The longer the array, the higher the maximum SPL and the longer the throw distance. Also, longer arrays can
vertically and digitally steer audio content down to a lower frequency, as indicated by Beam Control Limit.
The table below is a guide for these items:
Typical Usable
Throw Distance
1
Max SPL
2
Beam Control
LF Limit
Modules
10 m
20 m
30 m
1
10 m (33 ft)
97 dB
91 dB
88 dB
500 Hz
2
25 m (82 ft)
100 dB
96 dB
94 dB
250 Hz
3
35 m (115 ft)
101 dB
97 dB
95 dB
160 Hz
1
Typical Maximum Usable Throw Distance includes considerations for reverberation and speech intelligibility.
2
Max SPL calculated based on free-field (no boundary loading gain) sensitivity, exclusive of power compression, and without beam
steering, spreading or smoothing functions applied.
All calculations based on typical conditions with complex acoustic summation by Bose Modeler® software; many competitor specifications
based on less accurate, distance-loss approximations.
For applications that exceed the general guidelines listed above, use Bose Modeler® to predict SPL for a specific acoustic environment, or
contact your Bose Professional representative.
Conference rooms with lower ceilings and smaller steering angles may not have the same reverberation concerns and can mainly consider
Max SPL as a guiding factor for choosing between 1, 2 and 3 array modules.
Array Location (Height)
If you mount the array high on the wall and utilize a more significant steering angle closer to –20° and a wide
spreading angle to cover the front rows, a 2- or 3-module MSA12X configuration is highly recommended.
Dual Beam Mode
When using Dual Beam mode, it is recommended to use a 2- or 3-module MSA12X array for better pattern
control due to the longer array.
Reverberant Spaces
Generally, the primary use of columnar arrays are for speech reproduction. Also, most of these applications
tend to be highly reverberant spaces.
The rule for these venues is, as reverberation time increases, stack more modules.
RT60* for Medium
to Large Venues
1 module
1.5 sec
2 module
3.0 sec
3 module
5.0 sec
* These recommendations apply to “typical” medium sized venues with some rever-
beration concerns. In cases where your application exceeds the guidelines, design
tools such as Modeler software, should be used to determine system performance.
