The planned facility would have the ability to host hockey, volleyball and basketball - and music events. By the time Tommex joined the project team the main building was almost complete. Tommex started by preparing a mathematical model of the hall using Ease 3.0 software and the virtual acoustic reality of the hall was far from good. In every instance,measurements were made using Gold Line DSP 30 B to check the RT60 parametersand the poor measurements confirmed those gained from Ease. The RT60 at somefrequencies was almost 11 seconds. This presented Tommex with an enormouschallenge to meet the customer expectations of a venue for music events andspeech with good intelligibility.
The finance for Globus was already closed but a series of meetings between the client, the architects and Tommex persuaded the client to increase the budget for acoustic treatment. As a result, additional damping material on the ceiling and an acoustic screen above the main loudspeaker cluster were installed to the specification drawn up by Tommex. This resulted in an impressive decrease in average RT60 to below 3 seconds and RaSTI better than 0,5.
Tommex admit the room remains less than ideal for music events but it is possible to attain quite good speech intelligibility; a remarkable achievement given the original acoustics and limited budget.
With the reverberation time remaining high and still with poor acoustics, the choice of the loudspeaker system was critical for Tommex. They considered the solution of a multi-point projection system, based on Community R.5 or WET series loudspeakers but there remained two factors that could not be overcome: Firstly the budget for system - more loudspeakersmeant more amps and racks to drive them and also more batteries as the system also had to provide voice alarm as a core function. Secondly the budget for installation - more loudspeakers distributed in the hall would mean more cables and more installation work in the almost complete facility. Cables were a significant major cost as they had to meet the certified, fire proof specification.
The chosen solution therefore had to be a central cluster, using the power of Community R2s. After precise simulation Elisabeth Zieli?ski of Tommex chose the asymmetrical R2-694X. The well-controlled dispersion of the loudspeaker enabled the design to avoid serious reflections from vertical walls, particularly in the vicinity of corners. Another important consideration in choosing Community R series was the products inherent suitability for an ice arena application. Being weather resistant they would not be susceptible to the usual corrosion caused by the humid environment found in this type of facility.
Seven Community R2-694X and six Community R.5-66TX form the main cluster. The R.5s fire downward and provide good coverage to the central arena with the R2-694Xs covering the audience areas. With this solution the R2s are driven at only 200W, easily meeting the specification for the voice alarm system to have at least 10% reserve power.
Wojciech Zieli?ski, heading the Globus project for Tommex, says: "Final measurements confirmed the accuracy of the simulation and confirmed the importance of being able to use simulation in the design process for acoustically complex buildings. Of course this only works when a manufacturer's data for their products is totally accurate and honest and Community are outstanding in this respect. It makes our job a lot easier and gets better results."
Tommex used a base parameter for the system of 103 dB average SPL for 95% of the audience area with a frequency response of 100 Hz to 10 kHz. Additionall
