Arcline 8/212 User Guide V1.0
Page 51
Vector summation
Each Arcline 8 has 12° vertical HF coverage (i.e. -6 dB points 6° above and below axis).
Adjacent Arcline 8 outputs “sum” together with an efficiency that depends on the axis-to-axis
splay angle.
The process is often called vector summation as any phase difference between elements also
affects the summation.
The Arcline 8’s subtle HF wavefront curvature provides flexible vector summation. It provides
good, gap-free coverage at high splay angles whilst retaining excellent wavefront summation
for near-zero splay angles.
Assuming all the Arcline 8s HF sections are being driven with identical signals:
• Adjacent Arcline 8 HF outputs sum to a full 6 dB at 0° axis-to-axis inter-cabinet (splay) angles
• A flat array (all Arcline 8s at 0° splay angle) would sum to an extra 6 dB per doubling of cabinets
• Adjacent Arcline 8 HF outputs sum to approximately 0 dB (unity gain) at 12° inter-cabinet
angle – but with increased vertical coverage
• A wide variety of summation/coverage options are available for all the angles in between
Here’s an example of a real-world (i.e. finite-length, curved) Arcline 8 array:
Figure A.4: Array of 8 x Arcline 8 adjusted for very smooth
5 kHz octave coverage of a 35 m flat-floor venue
The inter-cabinet angles were adjusted in the above example for a very flat HF level coverage
(shown red above) to show what is possible by simply adjusting splay angles for the required
coverage. All Arcline 8s were driven in unison. Here’s a detailed illustration of what is going on:
Level changes are minimised by summing more and more cabinets to compensate for the
usual radial attenuation with distance. Front audience area A is served by just one Arcline 8 at a
time (7 or 8), area B with two (5 & 6), area C with three (3, 4 & 5), area D with five (1, 2, 3, 4 & 5)
and area E with four (1, 2, 3 & 4) – two of which are splayed at 0° to provide maximum on-axis
summation for the rear of the audience.
Figure A.5: Arcline 8 vector summation
(The cabinets are numbered from top to bottom – as per EASE
Focus 3 - with -6 dB lines HF coverage lines added for each cabinet)
11 Appendix A - Line array basics
Summary of Contents for Arcline 212
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