Performances and Design of Ironless Loudspeaker Motor Structures

Benoit Merit (1) , Guy Lemarquand (1) , Valérie Lemarquand (1)

1 LAUM - Laboratoire d'Acoustique de l'Université du Mans

This paper presents several kinds of structures of ironless loudspeaker motors. The proposed devices go from simple structures, in terms of manufacturing process, to structures in which the magnet rings can be stacked, with different magnetization directions or values. The structures are studied and compared according to their created induction level and uniformity across the coil displacement range, which are directly linked to the loudspeaker performances (force factor). The model used is the coulombian model of magnets to calculate the magnetic field created, therefore all the calculations are analytical. The paper shows that no structure is universal when it comes to the loudspeaker design: some are well adapted to micro displacements of the coil while other structures are adapted to large displacements.

Mots clés: Permanent magnets; loudspeaker motor; loudspeaker performance; motor design; analytical magnetic field calculation

Domaines: Electromagnétisme; Acoustique [physics.class-ph]; Acoustique [physics.class-ph]

Benoit Merit, Guy Lemarquand, Valérie Lemarquand. Performances and Design of Ironless Loudspeaker Motor Structures. Journal of Applied Acoustics, 2010, 71 (6), pp.546-555. ⟨10.1016/j.apacoust.2009.12.004⟩. ⟨hal-00462380⟩