Patent ID: 7006654

Claim:
An electromagnetic transducer comprising: (a) a push-pull magnetic circuit including, a top plate defining an upper magnetic air gap, a bottom plate defining a lower magnetic air gap, a total available magnetic air gap height comprising the upper and lower magnetic air gaps, and a magnet providing magnetic flux over the upper magnetic air gap in a first direction and magnetic flux over the lower magnetic air gap in a second direction opposite the first direction; and (b) a voice coil assembly including, a bobbin, an upper voice call having windings coupled to the bobbin, a lower voice coil having windings coupled to the bobbin, and a total available voice coil height comprising the upper and lower voice coils; (c) wherein the upper and lower voice coils are coupled to the bobbin at respective positions such that BOTH, less than 100% of the total available magnetic air gap height contains voice coil windings, AND less than 100% of the total available voice coil height is within the magnetic air gaps; (d) and wherein at least one of the voice coils is one of semi-overhung and semi-underhung.