On the Interdependence of Loudspeaker Motor Nonlinearities

Two of the main nonlinearities in the electrodynamic loudspeaker are the position dependence of the force factor, Bl, and the voice coil inductance, Le. Since they both are determined by the geometry of the motor structure, they cannot be independent. This paper investigates this dependence both analytically and via FEM simulations. Under certain simplifying assumptions the force factor can be shown to be proportional to the spatial derivative of the inductance. Using FEM simulations the implications of this relation is illustrated for drivers with more realistic geometry and material parameters.