Nonlinear modeling of the heat transfer in loudspeakers

Traditional modeling describes the heat flow in loudspeakers by an equivalent circuit using integrators with different time constants. The parameters of the lumped elements are assumed to be independent of the amplitude of the signal. The simple model fails in describing the forced-air convection cooling, which becomes an effective cooling mechanism if the velocity of the coil and/or the air velocity in the gap becomes high. A large-signal model which considers the nonlinear interactions between the electromechanical and the thermal mechanisms is described. The model and parameters are verified by practical measurements on the drivers. The dominant paths for the heat flow are identified, and means for increasing the power handling capacity are discussed.