Placement Of Entasys - Community ENTASYS Application Manual

SYSTEM DESIGN GUIDELINES
Low Frequency Section
The low frequency section of the ENTASYS Full-Range loudspeaker is approximately 44.5 inches (1129mm) in length. It offers
considerable directivity control at 1 kHz (the opening angle is slightly less than 20 degrees), but not quite as much control as it
has at 2 kHz or 4 kHz (where the opening angle narrows to approximately 10 degrees). At 500 Hz the opening angle is greater
still, resulting in even less directivity control. This is illustrated in the vertical directivity map (Figure 25).
By comparison, Figure 26 depicts a vertical directivity map for an array comprising one ENTASYS Low Frequency module
stacked on top of a Full-Range module. The opening angle of this array at 1 kHz is now much closer to the opening angle at
2 kHz and 4 kHz. In fact, the opening angle at 500 Hz is not much larger (just over 20 degrees), and at 200 Hz (the low
frequency limit of ENTASYS) the opening angle is only 60 degrees. If tighter directivity control is required in this frequency
region, the addition of a second Low Frequency module to the array will narrow it to an even more impressive 35 degrees
at 200 Hz.
This increased directivity control occurs only below 1 kHz, just where it is needed. If more Full-Range modules are added, the
opening angle above 1 kHz would also decrease. By adding Low Frequency modules to the array, we are only increasing the
length of the array at low frequencies.
Considering the Full-Range
The required height of an array is best determined with the use of an acoustical modeling program. As a rough rule of thumb,
one module should be used for every second of reverb time in the lower midrange region (typically 250 - 800 Hz). Hence, for
a room with an RT of approximately 2 seconds, two modules would be a good starting point. Referring back to the section on
Performance Comparison of a Line Array and Point Source System in the Same Room (Page 17), the room shown has a average RT of
approximately 2.5 seconds in the 250 - 800 Hz region. The SPL maps on the walls and the graph of C50 indicates that an array
comprised of one Low Frequency and one Full-Range module should work well.
Some applications may be better served in the high frequency region by using two or more Full-Range modules. The above
rule of thumb does not necessarily indicate that additional Low Frequency modules should be added to an array of three Full-
Range modules for use in a room with a 3 second RT (i.e., three seconds = three modules). Using all Full-Range modules or a
combination of Full-Range and Low Frequency modules could be equally effective.
Please keep in mind that this is just a rough rule of thumb. It is not meant to serve as a strict guideline. Every acoustical space
and each application is different, and "cookie cutter" approaches rarely work in the design of audio systems.
P L AC E M E N T O F E N TA SYS
Close to Performers/Presenters and Open Microphones
Selection of the correct microphone directivity pattern is critical in the proper design and installation of a sound system. The
high degree of vertical directivity control exhibited by ENTASYS systems typically allows for microphones to be located fairly
close to the loudspeakers. As with all loudspeakers, though, open microphones should not be placed too near the side or
directly in front of an ENTASYS system.
For applications where microphones are located between the loudspeaker and the audience, ENTASYS can be employed with
very good results. One key aspect for designs of this type is to ensure that the microphones are located above or below the
primary radiation beam. This is another situation where EASE Focus can be used to quickly determine the loudspeaker array's
SPL at a proposed microphone location. Using EASE Focus with a good estimate of the SPL from the presenter and their
distance from the microphone, the potential gain-before-feedback of the system can be calculated.
Of course, as more open microphones are connected to a sound reinforcement system, less gain will be needed to drive the
system into feedback. Note that the issue is not the microphones' distance from the loudspeaker, but from the primary beam
of sound being radiated by the loudspeaker. Using EASE Focus to visualize the vertical radiation from the loudspeaker array
will help in understanding the best microphone placement when used close to ENTASYS.
Community ENTASYS Application Guide - Page 28