PURPOSE: To increase the reproducing band by forming the diaphragm with the plane-type diaphragm and the conical diaphragm jointed to the node of the primary division vibration of the diaphragm.

CONSTITUTION: Plane diaphragm 1 is formed with the honeycomb structure, and the skin in formed with GFRP each. And diaphragm 1 is supported by edge 3 along with voice coil 2 provided at the lower part of the edge. At the same time, spider 4 is provided to improve the linearity. Then the node of the axial symmetric primary division vibration of diaphragm 1 is driven by conical diaphragm 6. As a result, the first division vibration features the secondary resonance to increase the piston vibration region. Thus the wide sound pressure-frequency characteristics can be obtained.