Neodymium iron boron and professional audio loudspeakers

Neodymium iron boron, a high reminence, high coercivity permanent magnet material, has been in use in the audio industry for several years in the form of small (approximately 1‐cm‐diam) disks in high‐performance microphones. Dropping prices and continuing enhancements in material properties, reducing thermal demagnetization and increasing residual magnetic flux density, have made neodymium more attractive for use in professional audio loudspeakers, where magnent size can reach 4 in. in diameter and almost 1/2 in. thick. While still considerably more expensive than the more commonly used ferrite ceramic magnets, neodymium magnet structures can be smaller and have a higher flux density than can be practically attined with ceramics. A specific example of loudspeaker motor structure design using neodymium—the Architectural Acoustics Neo Series Acoustical Components from Peavey Electronics—will be presented. Acoustical implications of high‐force loudspeakers on enclosure design will also be discussed. [Work supported by Peavey Electronics Corporation.]