This thesis treats the problem with nonlinearities in a loudspeaker driver. The hypothesis was: Can the harmonic distortion in a loudspeaker driver be removed using control knowledge? The loudspeaker driver was studied and a mathematical model of a driver was made. The mathematical model was analysed and reduced. To remove the harmonic distortion this thesis analysed the model, and located the nonlinear elements producing the harmonic distortion. A control scheme was presented and designed. The scheme consisted of a controller, a closed loop observer and a adaptive estimator. The controller designed, uses the nonlinear control type feedback linearization. The controller was simulated, and found usefull for reducing the nonlinearities in the driver. The controller had to be sampled with a larger sampling frequency han first assumed in order to completely remove the harmonics. A Kalman filter was developed as a closed loop observer to estimate the non measurable states of the system. The observer was tested, and found sufficient for this project. The adaptive estimator used a set of coefficients obtained from a Klippel Analyzer to extrapolate the parameters. Methods for estimating the nonlinear parameters of the driver are presented. The final simulation with the controller and closed loop observer, showed it was not possible to remove the nonlinearities of the driver, but it was proves possible to reduce them.