Vortex cooling of voice coils

1. A low frequency transducer arrangement comprising:

at least one substantially annular magnet;

a voice coil disposed within and concentric with the magnet;

a pole disposed within and concentric with the voice coil, an air gap being defined between the magnet and the pole, the pole including:

a bottom half having a downwardly facing axial recess, a plurality of first air passages extending laterally from the axial recess and fluidly interconnecting the recess and the air gap; and

a top half having an upwardly facing axial recess, a plurality of second air passages extending laterally from the upwardly facing axial recess and fluidly interconnecting the upwardly facing recess and the air gap, wherein the first air passages and/or the second air passages are non-radially oriented.

2. The arrangement of claim 1 wherein at least one of the first air passages and/or second air passages is arcuate.

3. The arrangement of claim 1 wherein the voice coil is moveable within the air gap in an axial direction.

4. The arrangement of claim 1 wherein the first air passages are substantially evenly spaced, and the second air passages are substantially evenly spaced.

5. The arrangement of claim 1 wherein each of the first air passages is offset from the radial direction in one of a clockwise direction and a counterclockwise direction, and each of the second air passages is offset from the radial direction in an other of a clockwise direction and a counterclockwise direction.

6. The arrangement of claim 1 wherein each of the first air passages is oriented tangentially relative to the downwardly facing axial recess, and each of the second air passages is oriented tangentially relative to the upwardly facing axial recess.

7. The arrangement of claim 1 further comprising a back plate supporting both the bottom half of the pole and the magnet, the back plate including:

an axial throughbore fluidly interconnecting the downwardly facing axial recess with ambient air; and

a ramped surface disposed at a same vertical level as the first air passages.

8. A low frequency transducer arrangement comprising:

an annular magnet;

a voice coil disposed within and concentric with the magnet;

a pole disposed within and concentric with the voice coil, a cylindrical air gap being defined between the magnet and the pole, the pole being at a substantially same vertical level as the magnet, the pole including an upwardly facing axial recess, a plurality of non-radially oriented first air passages extending laterally from the upwardly facing axial recess and fluidly interconnecting the upwardly facing recess and the air gap; and

an annular steel ring disposed below and concentric with the magnet, the annular steel ring at least partially defining an outer boundary of the air gap, the steel ring including a plurality of non-radially oriented second air passages extending laterally from the air gap and fluidly interconnecting the air gap and ambient air.

9. The arrangement of claim 8 wherein the first air passages and/or the second air passages are arcuate.

10. The arrangement of claim 8 wherein the first air passages are substantially evenly spaced, and the second air passages are substantially evenly spaced.

11. The arrangement of claim 8 wherein each of the first air passages and second air passages is offset from the radial direction in a same one of a clockwise direction and a counterclockwise direction.

12. The arrangement of claim 8 wherein each of the first air passages is oriented tangentially relative to the downwardly facing axial recess.

13. A low frequency transducer arrangement comprising:

two substantially annular and concentric magnets;

a voice coil disposed within and concentric with at least an upper one of the magnets;

a pole disposed within and concentric with the voice coil, an air gap being defined between the magnets and the pole, the pole including:

a bottom half having a downwardly facing axial recess, a plurality of first air passages extending laterally from the axial recess and fluidly interconnecting the recess and the air gap, the bottom half being at a substantially same vertical level as a lower one of the magnets; and

a top half having an upwardly facing axial recess, a plurality of second air passages extending laterally from the upwardly facing axial recess and fluidly interconnecting the upwardly facing recess and the air gap, wherein the first air passages and/or the second air passages are non-radially oriented, the top half being at a substantially same vertical level as the upper one of the magnets.

14. The arrangement of claim 13 wherein a magnetic polarity of a bottom surface of the upper magnet matches a magnetic polarity of a top surface of the lower magnet.

15. The arrangement of claim 13 wherein at least one of the first air passages and/or second air passages is arcuate.

16. The arrangement of claim 13 wherein the voice coil is moveable within the air gap in an axial direction.

17. The arrangement of claim 13 wherein the first air passages are substantially evenly spaced, and the second air passages are substantially evenly spaced.

18. The arrangement of claim 13 wherein each of the first air passages is offset from the radial direction in one of a clockwise direction and a counterclockwise direction, and each of the second air passages is offset from the radial direction in an other of a clockwise direction and a counterclockwise direction.

19. The arrangement of claim 13 wherein each of the first air passages is oriented tangentially relative to the downwardly facing axial recess, and each of the second air passages is oriented tangentially relative to the upwardly facing axial recess.