Analysis Of Optimization Design Of Phase Plugs In Horn Loudspeaker

The horn loudspeaker is consists of horn and loudspeakers. In the horn loudspeakers couple a radiating diaphragm to a horn throat of smaller area, resulting in high efficiency. This area reduction improves the match between the output mechanical impedance of the driver and the loading acoustic radiation. But when the diaphragm diameter is larger in the horn loudspeakers, the sound wave which send out from the center part of the diaphragm and the sound wave send out from the around part of the diaphragm meet in the throat. When the furthest distance from a point on the diaphragm to a channel is a half-wavelength, we could expect some destructive inference to occur. Seriously affect the acoustic performance of the horn loudspeakers. In order to avoiding the destructive interference, phase plugs are designed in the horn loudspeakers. In addition, the modal of the air vibration between the diaphragm and phase plug will lead to peak valley occur on the frequency response curve. Therefore The phase plug design is a key problem of the horn loudspeaker design.The goal for the horn loudspeaker phase plug design is to make the acoustic frequency response curve flat and high frequency width as far as possible.There are two design methods of the phase plugs in the horn loudspeakers, which is Equal-Path-Length Approach and Modal Control by Channel Balancing. The former is to avoid the reverse phase interference and The latter is to reduces the peak valley which caused by the air eigenvibration between the diaphragm and phase plug cavity.This article about optimization design of the horn loudspeaker has carried out the following work:1. Reviewed and summarized the theoretical basis of the Equal-Path-Length Approach and Modal Control by Channel Balancing.use the Simplified model which made of the flat disc diaphragm and the thin cylindrical cavity and the real model which made of the spherical diaphragm and the spherical cavity.2. Solved mode and natural frequency of the air vibration in the spherical cavity. Which has been adopted FEM. This article adopts the method of mobile launch center to get the air inside the cavity vibration mode and natural frequency of the power series form analytical solution. Further converts air vibration equation approximate to zero order Bessel equation, the approximate solutions are obtained. The precision of the approximate solution can completely meet the engineering requirements. The computer program was compiled with FORTRAN language Program can not only calculate the modal and natural frequency, at the same time that according to the theory of modal elimination method to calculate the phase plug channel and each channel area ratio.3. we used the FEM to numerical simulation analysis and design of the phase plug. We use the FEM software Virtual Lab to created the simplified model and actual model, respectively adopt such as path length method and the modal elimination to analysis the optimized parameters of the phase plug.