PURPOSE: To ensure the good frequency characteristics for the rear-type horn speaker with equalizer, by forming the high-elasticity and high-accuracy edge which is free from the mechanical distortion statically and even with the vibration.

CONSTITUTION: When the acoustic current flows to voice coil 8, coil 8 vibrates in the axial direction and within the magnetic gap formed between pole piece 3 and yoke plate 5. This vibration is damped by the support bar at edge part 30 and also transmitted to diaphragm 29 to cause vibrations. In this case, part 30 is made of the material having a high modulus of elasticity such as the beryllium steel and has a number of support bars 32 arranged in the direction of the circumference. As a result, part 30 shows the flexible property in the axial direction and bends by the fixed elasticity and according to the minute rotation but is hard to move to the lateral direction vertical to the axis to cause no displacement substantially. Accordingly, the relative positioning in the lateral direction can be obtained in a high accuracy between part 30, diaphragm 29 and coil bobbin 7 each. Thus diaphragm 29 can have the piston motion with no lateral shift.