Loudspeaker impedance emulator for multi resonant systems

Specifying the performance of audio amplifiers is typically done by playing sine waves into a pure ohmic load. However real loudspeaker impedances are not purely ohmic but characterised by its electrical, mechanical and acoustical properties. Therefore a loudspeaker emulator capable of adjusting its impedance to that of a given loudspeaker is desired for measurement purposes.

An adjustable RLC based emulator is implemented with switch controlled capacitors, air gap controlled inductors and potentiometers. Calculations and experimental results are compared and show that it is possible to emulate the loudspeaker impedance infinite baffle-, closed box- and the multi resonant vented box-loudspeaker by tuning the component values in the proposed circuit.

Future work is outlined and encourage that the proposed impedance emulator is used as part of a control circuit in a switch-mode based impedance emulator.