Abstract
Moving-coil loudspeakers generally exhibit poor response in the low- frequency range because the diaphragms are unable to produce sufficient volume velocity. To alleviate the problem, this study focuses on enhancing the low-frequency performance of loudspeakers by means of modem control techniques. A self-sensing velocity observer is utilized for producing the cone velocity signal required by the controller. Feedback H(∞) robust control and feedforward H 2 model matching control are employed to simultaneously achieve robust stabilization and tracking performance. The proposed controller is implemented using a combined digital signal processor and operational amplifier circuitry. Modern control techniques are exploited to enhance the low frequency performance of moving coil loudspeakers, under the electromagnetic properties and acoustical constraints. A self sensing velocity observer is developed for cone velocity estimation without additional motional or acoustical sensors. H ∞ feedback control is employed for robust stabilization, while the H 2 feedforward model matches control for tracking performance. The proposed system yields improved performance over the uncompensated one. The effectiveness of the method depends on the adequate design of the original mechanical system and acoustical system.