Patent ID: 8781150

Claim:
A low frequency transducer arrangement comprising: a pole piece; a substantially cylindrical structure surrounding the pole piece; an air gap, wherein the air gap is between the pole piece and the substantially cylindrical structure, the air gap is substantially cylindrical, two opposite ends of the air gap both being open to allow air to flow through the air gap and separated from each other in an axial direction; a first magnet being disposed in either the pole piece or the substantially cylindrical structure; a second magnet being disposed in either the pole piece or the substantially cylindrical structure, a middle magnetic gap separating the second magnet in the axial direction from the first magnet; a top magnetic gap being disposed axially adjacent the first magnet and opposite the middle magnetic gap; a bottom magnetic gap being disposed axially adjacent the second magnet and opposite the middle magnetic gap; and a voice coil at least partially disposed in the air gap and configured to operate in the middle magnetic gap, wherein the first magnet and the second magnet provide flux in a same direction in the middle magnetic gap, and wherein the opposite end of the air gap axially adjacent to the bottom magnetic gap has direct access to ambient air.