The term “line array” covers a breadth of product offerings, from 2-way loudspeakers with a few components and passive crossover networks to highly complex, multi-transducer systems with separate amplification and DSP for each component.
The key commonalities are: a) that a number of these enclosures are stacked together in a column (and typically flown); b) that the column of devices is intended to provide full-bandwidth coverage over a specific horizontal swath both near and far; and c) that the sum of their audio output provides a relatively coherent sound wave across the listening area with its vertical pattern control down to a particular frequency being controlled by the coupling of the aligned components and the physical length of the array.
Let’s explore some of the latest technologies used within line arrays to further improve their performance, including transducer and system control innovations as well as advancements that aid design, manufacturing, measurement, and application.
Advanced Design Tools
Line array manufacturers are able to take advantage of a variety of modern design and engineering tools that add precision and predictability to their product development process. The speed and power of computing has allowed real-time analysis of audio signals and the ability to visually display the resultant audio measurements, so that iterations of a design can be evaluated and compared.
Thermal imaging looks inside a functioning transducer and visualizes the heat transfer while laser interferometry provides vibration analysis of transducers and enclosures. CAD programs can model complex architectures and help the designer fit together pieces of the system before having to physically build a model. And when creating initial design prototypes, technologies like 3D printing and programmable machining tools can accelerate the process while lowering the cost of multiple iterations and improvements.
When the systems are ready to be built, computer-aided manufacturing tools can create precise, repeatable transducers and internal structures so that the acoustic performance of the resulting line array model is consistent. This also extends to the measurement and selection of electronics components, so that these parts ¬– and the amps and DSP control circuitry they become – will remain within defined performance parameters.
In conjunction with an anechoic chamber or other controlled acoustic space and rotational devices to retain and move the test piece, very precise polar measurements of specific enclosures can be made and then used to virtually represent the performance of that system within prediction software.
The software is able to place virtual arrays within the floor plans of specific performing venues and generate coverage maps at different frequency bands over defined coverage areas, also illustrating constructive or destructive interaction among the loudspeakers depending on their placement.
Examples include L-Acoustics SoundVision, Meyer Sound MAPP, Adamson Blueprint AV and EAW Resolution, to name a few. Another approach provided by Renkus-Heinz is the inclusion of VARIAi 101 array data in EASE and EASE Focus II simulation software to quickly and accurately predict the response of an array. Then during application, acoustic measurement platforms such as Rational Acoustics Smaart, AFMG SysTune, and Meyer Sound SIM 3 help fine-tune performance.
At the heart of all of these loudspeakers are the acoustic elements – the transducers, horns, and waveguides. Ongoing innovation strives to make these electro-mechanical devices more reliable and consistent, accurate in their response characteristics even when pushed to their limits, thermally stable, and electrically efficient.
In most cases, transducers have been designed specifically for use in particular line arrays, as contrasted with earlier times when a manufacturer’s available components were used to create loudspeaker systems.
Assisting the specialized transducers, innovative waveguides and horn technologies aid in maintaining consistent directivity when crossing between components, help ensure even frequency response, and allow adjacent enclosures to function together seamlessly.
The midrange cone drivers within RCF’s recently released HDL 6-A compact line array have specially developed 2-inch inside and outside voice coils, with a polyimide former sandwiched in between.
This technology is designed to double the thermal dissipation surface area along with the adhesion area to the former for increased mechanical resistance.
Modern line array pioneer L-Acoustics utilizes a K-shaped coplanar transducer configuration along with its DOSC waveguide to maintain symmetrical horizontal coverage in systems such as the K1 and K2.
In the compact KARA, the K-shaped transducer configuration generates a specified symmetric horizontal coverage of 110 degrees, which the company notes is without secondary lobes over the entire frequency range. Further, any KARA array can be curved up to a maximum of 10 degrees for each element without breaking the inter-element acoustic coupling.
Alcons Audio deploys a unique 14-inch tall, single-diaphragm ribbon transducer running top to bottom on its LR28 enclosures, covering the top octaves of acoustic output. VUE Audiotechnik utilizes beryllium compression driver domes because the material can reduce mechanical deformation of the diaphragm “while shifting resonant frequencies above the range of human hearing.”
The design also seeks to minimizes power compression effects over time, notes VUE CEO Ken Berger, who adds, “Our goal is to make the system perform just as good after the encore as it did at the beginning of the show.”