Applications of network synthesis to loudspeaker system theory

The acoustical circuit of a loudspeaker in a vented box or in a closed box, approximates closely, over its piston range, to a high-pass filter of fourth-order or second-order respectively. The component values of the filter can easily be measured in a form suitable for analysis using readily available electrical measuring equipment and an enclosure of known volume. From this data, loudspeaker systems can be synthesized as filters, using composite structures containing both acoustical elements and electrical elements such as equalizers. These structures can be optimised for a desired response or for minimum box size or amplifier power or maximum power capability or a compromise between all these factors. Design considerations and methods are outlined for arriving at these optima.