Design Application Examples; Highly Reverberant House Of Worship - Community ENTASYS Application Manual

HIGHLY R E V E R B E R A N T H O U S E O F WO RS HI P
Design Approach
This house of worship, exhibits a mid-band RT of 3.0 - 3.5 seconds; RT increases to 4 - 5 seconds at frequencies below 500
Hz. In this case, the RT was measured live and then input to EASE in order to more accurately evaluate intelligibility
(Reference Figure 33). The primary reproduction for this application will be spoken word. This is a challenging space due to
its highly reverberant nature. Subwoofers are not shown in this design but could be added easily with no detrimental effects.
It is important in this application to maintain good directivity control and keep as much energy as possible off the ceiling and
upper walls to avoid exciting excess reverberation. Therefore, neither subwoofers nor low frequency extension loudspeakers
will be used. Cost is also a factor, so a minimum number of loudspeakers and channels of amplification will be used. Aesthetics
is also a concern, and the less visually obtrusive the system can be, the better.
A minimum number of installation locations are preferred for this project to minimize architectural impact. Two arrays, three
modules tall at the front of the room can provide marginally acceptable intelligibility for 80% of the audience. Despite the very
high directivity of the ENTASYS full-range modules, a distributed approach yields higher intelligibility by way of providing high
levels of direct sound to the audience compared to reflected sound.
Therefore, the preferred method locates one ENTASYS full-range module at three locations along the sides aimed at the
audience. Each Full-Range module mounts snugly to the structural columns as shown in Figure 32. Progressive signal delays
must be applied to units farther from the Full-range units at the front of the audience. Each delay can be synchronized with
the direct sound from the front full-range units so as to maintain the perception in the audience's mind that the sound
proceeds from the forward units.
EASE Focus can be used to evaluate the need for any vertical down-tilt which was not needed due to the audience members
position in the system's near-field. Also, all listeners are located within 35 ms of each array. Therefore, they will perceive the
direct sound of multiple loudspeakers as integrated.
The azimuth (horizontal aiming angle) of the arrays must be adjusted in the EASE 3D model to achieve optimal coverage. This
is accomplished by aiming each of the modules inward 15-28 degrees.
Results
The audience area shown in Figure 34 indicates very uniform direct SPL ranging from 101 dB in front to 98 dB in the rear.
The C50 (clarity) of this system in the audience area is -5 dB (+/- 1 dB). This correlates with an STI of 0.45 - 0.58 and a
%Alcons of 7.8 - 10%, and should result in very good speech intelligibility given the reverberant behavior in this room.
What To Look Out For
Generally, taller arrays of ENTASYS columns with additional LF modules will help to maintain consistent directivity control
over very low frequencies. By harnessing this characteristic of line array technology, stimulation of low-frequency resonances
can be avoided.
Loudspeakers, Brackets, and Power Amplifiers Used in This Design
•
(6) ENTASYS Full-Range Modules (ENT-FR (curved)) - three per side
•
(6) ENTASYS Pan Brackets (ENT-PB)
•
(3) Two channel amplifiers rated at 3,600 W per channel into 4 ohms for maximum power
However, lower levels may be sufficient. See Pages 16-17 regarding amplifier selection.
•
(1) High pass filter or DSP unit with 2 output delays
DESIGN APPLICATION EXAMPLES
Community ENTASYS Application Guide - Page 38