Audio Engineering Society UK

Title: ‘Improved methods for controlling touring loudspeaker arrays’
Location: Royal Academy of Engineering, London
Description: Lecture by Ambrose Thompson, Martin Audio
Start Time: 18:30 for 19:00
Date: Tuesday 9th March 2010

The focus of this paper is a popular type of line array loudspeaker used for large- and medium-scale sound reinforcement. These systems are required to deliver very high SPL to a large audience area sometimes as far as 100m from the array, but typically in the 30-70m range. This class of line array is characterised by relatively widely spaced acoustic sources, each with high vertical directionality compared to the more traditional steered column loudspeaker where the acoustic sources are small and tightly spaced. These differences, together with the fact that large audience regions are typically in the near-field, preclude the use of the existing techniques to control linear arrays.

Currently successful methods of control were examined and found to be inadequate for meeting a new more stringent set of user requirements. This paper describes how users of the modern articulated line array loudspeakers used for high level sound reinforcement can control these systems with more precision, and explains how these requirements can be formed into a mathematical model of the system suitable for numerical optimisation. The primary design variable for optimisation was the complex transfer functions applied to each acoustic source. How the optimised transfer functions were implemented with IIR/FIR filters on typically available hardware is explained, and a comparison made between the predicted and measured output for a large array.