The configuration is provided with three flexible arms extending in the same circumferential direction, as a suspension for supporting the magnetic circuit unit in displaceable fashion in the vertical direction with respect to a coil support member. This assures sufficient length of each of the flexible arms, enhancing the vibration characteristics. Next, arm insertion slots having approximately the same vertical Width as the flexible arms are formed at three locations in the circumferential direction in the coil support member. The distal end of each flexible arm is then inserted into the arm insertion slot, doing so in the aforementioned same circumferential direction, causing a barb to engage an engaging part and detain the flexible arm.