A circus arena is always a very complex acoustically object and solving the problem of uniform sounding with a minimum of reflections and good intelligibility is not an easy task for sound engineers-designers. And here it is worth mentioning several factors: first at all, the dome of the circus serves as a collecting bowl for sound, creating many reflections and significantly increasing the reverberation time, which degrades intelligibility and sound quality. Therefore, it is important to direct the maximum sound energy to the audience and the minimum to the dome structure. At the same time, the seats are located in a circle in the amphitheater and the sound should cover the seats of all spectators. The speakers should be located at the same distance from the audience and have the appropriate dispersion.
The second important factor is the large dome height of 22 meters and the need to preserve the circus rigging for aerialist and acrobats to work, which significantly limits the possibilities for rigging. As a consequence of the height, there is a large delay in the audio signal if the speakers are placed in the top of the dome. Accordingly, there is a great difficulty of working for live musicians, singers and even dancers.

The previous version of the system consisted of four 15"point loudspeakers in the upper center of the dome and four 18" subwoofers arranged vertically (End Fire Array), front side down, behind the dome grill. If the option with subs can be noted for a rather interesting idea, then the solution with tops absolutely did not fulfill the tasks assigned to it, the loudspeakers in this configuration could not provide sufficient pressure and intelligibility at such distance from the audience. And their location at the base of the dome, multiplied by the uncontrolled dispersion, provoked a huge number of reflections from the walls. The result is a mushy, droning, unintelligible, "wadding" sound for the audience.
They tried to solve the problems with the help of sound "crutches", hanging some more acoustic systems around the hall, but if improvements were achieved for some zone, then for the rest it became even worse, sound sources that were not coordinated in time were added, adding mushy sound.
The issue had to be solved in a radically different way, for this Lightek, the company in charge of the audio restyling appointed the leading Sound Engineer - Oleksii Malainyi, who proposed his own draft solution. The idea was to place line arrays in a circle, each of which would cover only its own sector of the amphitheater. At the same time, lower them as low as possible and close to the audience. A separate small array aimed at the stage was provided from the side of the gate under the orchestra.
In this way several problems were solved at once: the same distance from line arrays to spectators was obtained throughout the amphitheater and no zone loudspeakers are needed. At the same time, each segment of the auditorium actually hears only its own array, so they do not interfere with each other and do not provide a sound mess. Due to the closer distance and less air volume between the speaker and the viewer, the sound pressure of the acoustics is used more efficiently and the HF loss is lower. Thanks to controlled dispersion, sound energy goes where it needs to be and reflections from the dome are minimized; minimization of latency by almost twice; separate monitoring for the scene at a much closer range than main PA. The most difficult thing was to rig the system at such a height so as not to touch anything important or interfere with the rigging for aerial stunts, without which the circus is unthinkable.

When the concept was ready and approved, it remained to choose and calculate the audio system. Considering that this is a communal facility and line arrays required at least 4 cabinets per hand with a good coverage angle, the systems had to be not very expensive, but of high quality. The choice fell on 8” inch three-way line arrays - dBTechnologies DVA T8. On their side was affordable cost, light and active design with in-built amplifier and DSP processor, sufficient dispersion and decent sound quality. As a result, we got 4 arrays consisting of 6 cabinets each + 3 cabinets for the monitor cluster, 27 DVA T8 in total.
Implementation
Electric winches were used to lift and rig the arrays, all systems are connected to the RD-Net network, and each speaker can be controlled from the sound engineer's place. It took many hundreds meters of cable, but the advantage was the factor that the acoustics are active, with their own amplification and there are no losses on the acoustic cable.

The signal from the remote control comes digitally (AES / EBU) to the dBTechnologies AC26N processor, which is located above the dome, thus minimizing possible losses in the analogue audio signal transmission. The processor is also connected to RD-Net and controlled remotely. 4 channels are used for line arrays and one more for subwoofers.

Of course, the sound has changed, this is now a completely different level of sound reinforcement that meets modern requirements. A toolkit has appeared for precise and convenient adjustment of each element of the system from the sound engineer place. “This is probably the first time in this hall that such smooth coverage and intelligible sound has been achieved for each seats of the audience. Every word is heard, articulation and timbre are clearly conveyed. This is just a miracle and a huge leap forward after what we had before. It has become much more pleasant to work, and the result is now predictable and manageable ”- Evgeniy, Sound engineer of the National Circus.
Finally, dynamics and texture has appeared in the sound, so necessary for pop performances and dances, and the orchestra began to sound fully.