Convention Paper
Temperature stability of Neodymium magnets in voice coil transducers
AES Convention 150 · Paper 10460 · May 2021
Abstract
Sintered neodymium magnets enjoy continued popularity in electro-acoustic transducers due to their high energy density, which enables the design of lightweight and efficient products. Various, quasi-standardized grades are available which differ in remanence, coercivity, and temperature stability. The latter is depicted in a series of B-H curves in the material datasheet; correctly interpreting them requires a detailed calculation of the complete magnetic circuit. In typical voice coil magnet systems, the presence of the magnetic circuit has quite a favorable effect, preventing thermal demagnetization in a certain temperature range above the nominal temperature limit. Methods and experimental data regarding this question are presented in this paper. Furthermore, the progression of thermal demagnetization over time is researched and presented, and shows interesting characteristics which can be quite relevant in practice, both for cost efficiency and for environmental impact.
