Establishment And Study On The Virtual Prototyping Of Loudspeakers

As the terminal part of sound reproduction system, the sound quality of loudspeaker will affect the performance of the entire sound reproduction system directly. Since the loudspeaker was invented, from empirical research to parametric study and then to computer simulation, electro-acoustic engineers have been seeking convenient and effective methods to design high quality loudspeakers, but this is not an easy thing. The concept of virtual prototyping for loudspeaker’s design and analysis is introduced in this paper. Virtual prototyping, using simulation software to predict its performance before a physical prototype is made, can significantly reduce the number of physical prototypes, shorten development time and save investment. As well as a learning tool, it will help gain a deeper understanding in terms of the physical nature.The virtual prototyping for axisymmetric electrodynamic loudspeaker is built by using the finite element analysis software COMSOL in this paper, and the feasibility of the virtual prototyping is verified by experiment. It achieves the full coupling between electromagnetic, mechanical, and acoustical domains, and realizes the process from voltage input to sound pressure output. Without the use of any simplified lumped parameter, only through the CAD model and accurate material parameters, the T/S parameters, electrical impedance, acoustic frequency response and so on can be obtained. Some studies have been done based on the virtual prototyping, such as the study on coppering ring, dust cap and phase plug, nonlinear force factor of magnetic system. Considering the air viscous in the magnetic air gap, the virtual prototyping will be more accurate.The virtual prototyping is built on the basis of small signal and linear range, the nonlinear behavior of loudspeaker is not considered. It is sufficient for recreating the most commonly used small signal performance measurements. The nonlinear behavior of loudspeaker mainly occurs at low frequencies when the displacement is large, so it can be studied using the lumped parameter model. By solving the nonlinear differential equations of motion numerically using COMSOL, the harmonic distortion and intermodulation distortion which is based on the nonlinear parameters such as the nonlinear mechanical stiffness of suspension and the nonlinear force factor of magnetic system can be predicted. The nonlinear stiffness of spiders and surrounds can be measured and fitted respectively before assembled into loudspeakers, which spider works best with which surround is studied. When choosing spider and surround properly, the nonlinearity of the suspension can be reduced.