Dome speaker with cut-out portions in the voice coil bobbin

摘要

A structure for a dome speaker includes a dome-shaped diaphragm formed of a high rigidity material and having an outer periphery, a voice coil bobbin secured at a top end thereof to the outer periphery of the diaphragm, a voice coil mounted about the bobbin, and a variation means in the bobbin for varying the resonance conditions of the diaphragm. The variation means includes at least one cut-out portion provided at the top end of the bobbin and a sheet which closes the cut-out portion. Preferably, the diaphragm is made of a nitrified titanium alloy and the sheet is made from a material softer than the bobbin. The cut-out portion may have a width from about 7 to about 50 percent of the total circumferential length of the bobbin.