IMPROVED MOVING COIL TRANSDUCER

A moving coil transducer which comprises a yoke, permanent magnet and pole piece which are assembled to form a magnet circuit leaving an air gap between two opposing surfaces of the yoke and pole piece for receiving the moving coil. The permanent magnet is positioned between other opposing surfaces of the yoke and pole piece, and its faces are not parallel. Thus the thickness of the magnet increases away from the air gap of the magnetic circuit. In an annular or toroidal design in which the pole piece, permanent magnet and yoke are all annular and define an annular air gap, the magnet may be of conical form, having a thickness which increases away from the air gap. The pole piece and yoke are correpondingly tapered at the portions which meet the permanent magnet. The use of the non-flat magnet allows more magnetic material to be included in the transducer without increasing the overall volume of the transducer. This results in an increased magnetic flux density in the air gap and thus an increase in power and/or efficiency.