Optimal design of loudspeaker systems based on sequential quadratic programming (SQP)

Abstract

Miniature loudspeakers are key components to many 3C (computer, communication, and consumer electronics) products, especially for portable devices such as mobile phones, PDAs, and MP3 players. Due to size limitation, miniature loudspeakers suffer from the problem of low output level. To gain higher output, one tends to drive the miniature loudspeaker over the excursion limit and induce nonlinear distortion. Thus how to best reconcile the conflicting requirements of nonlinear distortion and acoustic output is extremely crucial in the design of such loudspeakers. To address the issue, a systematic procedure is presented to pinpoint optimal designs appropriate for miniature dynamic moving-coil loudspeakers. The optimization procedure is based on an electroacoustic model established by using the test-box method. Characteristics including voice-coil impedance, frequency response, and harmonic distortion are evaluated. The results show that significant improvement in output performance and excursion limitation has been gained by using the optimal design.