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Martin Audio Introduces OmniLine
OmniLine is a versatile, micro-line array designed for installation in a wide variety of architectural environments. Its modular approach and scalability extend its use from foreground applications to sound reinforcement in large acoustic spaces. Intelligent software enables an array to be configured to deliver sound precisely over any vertical angle to fit the venue profile without spilling onto surfaces where sound is not required. Additionally, elimination of high-frequency side-lobes gives OmniLine the advantage over currently available DSP steered columns, making it suitable for high quality music reproduction as well as speech in large, reverberant spaces.
Each OmniLine array is constructed by connecting together multiple array modules. Up to 32 modules can be connected where both high output and vertical focussing down to low/mid frequencies are required. Smaller number of modules (down to 4) can be used for shorter-throw applications, where vertical focussing of the low/mid frequencies is less important. This scalability means that OmniLine can be used in an extremely wide variety of applications – from bar and sports venues to churches and large public spaces. Visually, an OmniLine array is slim and unobtrusive, with soft lines that minimise its visual presence in an architectural environment.
Rather than applying DSP to a traditional column, OmniLine’S vertical beam-forming is achieved by physically articulating individual array modules to curve the array. The actual array configuration for a specific venue is determined by powerful, patent-pending optimisation software which makes intelligent judgements about the ‘goodness’ of the arrays SPL distribution against objective target functions. This enables focussed sound energy to be delivered precisely where it is needed and kept away from reflective surfaces and ceilings. It also means that all the energy produced by the array transducers is utilised additively, at all times, unlike some flat, steered columns which need to taper the output of the outer drivers to produce wider beams. By configuring the array physically in accordance with the optimisation software, the SPL distribution of an OmniLine array can be exactly contoured to the shape of the venue, at all frequencies.
OmniLine has been developed using sophisticated, in-house mathematical modelling software which enables the acoustic field at any point to be determined from multiple acoustic elements, using a combination of actual measurements, theoretical elements or BEM (Boundary Element Method) models.
The module consists of 2 x 3 ½” reflex-loaded, low/mid radiators either side of a central strip of 5 x 14mm HF devices in a unique, patent-pending arrangement. All drive units have been painstakingly developed from the ground up, specifically for the array module.
The horizontal coverage angle of the array is 100° at the -6dB points. Its constant-directivity pattern control is exemplary, with ultra-smooth off-axis frequency response curves that track the on-axis response exactly. The constant-directivity characteristics are not confined to the HF section, but are maintained down through the midband by the very close physical spacing of the low/mid drivers.
The close spacing is achieved by mounting the low/mid drivers in the HF waveguide walls - an arrangement which would normally have a detrimental effect on both the horizontal dispersion and frequency response due to the waveguide walls being interrupted by the resonant cavities in front of traditional cone drivers. However, in the OmniLine module, the unique 3D sculptured ‘cones’ follow the profile of the waveguide walls, permitting flawless performance from both the low/mid and HF sections.
Vertical coverage is tailored specifically to the venue by the intelligent optimisation software and sonically, the array is very clean and musical, with a smooth, full-frequency performance down to 70Hz.
A new intelligent optimisation process (patent-pending) has been specifically developed for configuring OmniLine arrays. This process starts with a new way of looking at things. The frequency response of a candidate array is ‘measured’ virtually at 100 or more ‘microphone positions’ in the venue - taking in both the audience planes where the sound is required - and planes, such as the ceiling, where it is not. These responses are viewed in IndexPlot - a new proprietary 2D presentation format, which shows clearly how loud the array is at all the ‘microphone positions’ in the venue and at all frequencies.
The intelligent optimisation process uses genetic algorithms to iterate configurations of candidate arrays against various target functions - such as frequency response, overall shape and level, response flatness, choppiness and sound leakage into non-audience areas. Indicators of ‘goodness’ for the SPL distribution are presented to the user as ‘levers’ for array design to enable the user to influence the array design process according to priorities.
Once the array configuration has been specified by the software, the array is assembled mechanically by means of integral inter-connecting brackets, which accurately position each module relative to its neighbour. Each array is constructed in multiples of 4 modules to make up arrays of 4, 8, 12, 16, 24 or 32 modules. Suitable array impedances are determined by simple series/parallel wiring in blocks of four modules.
In picture: Martin Audio engineering director, Bill Webb, demonstrates the weight advantages of the new OmniLine on the stand at PLASA.
17th September 2007
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