A loudspeaker includes a motor assembly including a magnet having a first face and a second face, a back plate abutting the magnet first face, a pole piece centrally disposed with respect to the back plate and extending beyond the magnet second face, and a top plate concentrically disposed with respect to the pole piece and extending beyond the magnet second face. A non-magnetic conducting frame is attached to the top plate, a non-magnetic conducting cap is disposed within the motor assembly and encircling the pole piece, a first non-magnetic conducting ring is disposed within the motor assembly and encircling the pole piece, and at least one second non-magnetic conducting ring is disposed within the motor assembly and abutting the back plate.