Patent ID: 7539318

Claim:
A speaker unit comprising: a magnetic circuit having a disk shaped magnet whose both surfaces are magnetized; a pair of magnetic gaps formed at positions near both surfaces of the disk shaped magnet inside the magnetic circuit; a pair of voice coils arranged in a manner corresponding to the pair of magnetic gaps, respectively; and a pair of diaphragms which are driven by the pair of voice coils, respectively, and which radiate acoustic waves in directions opposite to each other, wherein the magnetic circuit includes; a pair of plates fixed to both surfaces of the disk-shaped magnet, respectively, a cylindrical yoke arranged, with a spacing equivalent to the magnetic gap, apart from a peripheral surface of each of the disk-shaped magnet and the pair of plates, and a magnet holder to be fixed to the peripheral surface of the disk-shaped magnet, wherein the cylindrical yoke is fixed to the disk-shaped magnet via the magnet holder.