Abstract
A universal design procedure is presented for enhancing the low-frequency responses of loudspeakers ranging from handset microspeakers to subwoofers. This procedure aims at finding the optimal parameters of vented-box configurations using a systematic procedure based on vibration-absorber theory. By viewing the system as two coupled serial and parallel oscillators, a characteristic equation is derived for the vented-box system, A simulation platform is then established using electro - mechano - acoustical (EMA) analogous circuits. The electrical impedance and the on-axis sound pressure level (SPL) of the loudspeaker can be simulated by solving the loop equations of the analogous circuit. In order to facilitate the design process of such loudspeaker systems, a design chart is devised using the characteristic equation in deciding the parameters to deliver maximum output at the low-frequency end. In addition, a constrained optimization procedure is applied to maximize the acoustic output under the enclosure constraints. Simulations and experiments were undertaken to validate the resulting optimum design. Design guidelines are summarized.