Characterisation and modelling of loudspeaker cone resonance
Loudspeaker cone resonance (“cone break-up”) is a fundamental cause of ripple in the electrical impedance and sound pressure responses of electrodynamic loudspeakers. In this thesis, the dependence of the characteristics of loudspeaker cone resonances on the material properties and thickness profile of the cone is extensively determined by creating 2D and 3D finite element models of a 6½-inch polypropylene-cone loudspeaker. Techniques for adjusting the resonant characteristics of loudspeaker cones by varying the material properties and thickness profile of the cone are explored and summarised. The effect of cutting narrow slots through the surface of a loudspeaker cone is determined using 3D finite element modelling techniques, and cone slots are shown to have a large influence on the characteristics of the loudspeaker cone. A slotted loudspeaker cone with desirable impedance and sound pressure response characteristics is modelled and constructed. The measured response of the slotted loudspeaker is demonstrated to be a significant improvement over the characteristics of an unslotted loudspeaker.
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