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 characterized by the mechanical resonance between the mass of the diaphragm and the compliance of its suspension which vary from driver to driver. Therefore, a loudspeaker emulator capable of adjusting its impedance to that of a given driver is desired for measurement purposes. This paper proposes a loudspeaker emulator circuit for small signals. Simulations and experimental results are compared and show that it is possible to emulate the loudspeaker impedance with an electric circuit and that its resonance frequency can be changed by tuning two resistors.
Journal of Audio Engineering Society, 2014, Vol 62, Issue 10, p. 676-682