Patent ID: 7492918

Claim:
An audio speaker driver comprising: (A) a motor structure having a magnetic circuit including a magnetic air gap; and (B) a voice coil assembly disposed within the magnetic air gap and including, (1) a bobbin, and (2) a voice coil coupled to the bobbin, wherein the voice coil includes, (a) a center set of voice coil windings of wire wound about a center portion of the bobbin, and (b) an outer set of voice coil windings of wire wound about outer portions of the bobbin above and below the center portion, (c) wherein in at least one of, (i) the center set of voice coil windings has a higher average electrical resistance per unit of voice coil height than the outer set of voice coil windings, and (ii) the center set of voice coil windings has a longer average length L per unit of voice coil height than the outer set of voice coil windings.