Abstract:

Planar magnetic loudspeakers with wide diaphragms, such as woofers and midranges, are usually constructed using vertical rows of magnets with each row alternating between north and south poles. Narrow planar magnetic loudspeakers, usually called ribbons, are constructed with the diaphragm directly between the north and south poles of the magnet so it is totally immersed in the magnetic field. In this project, a loudspeaker with a 31/2-in.-wide diaphragm was designed and constructed with the ribbon configuration since the magnetic field is more linear with diaphragm excursion and is distributed more evenly over the surface of the diaphragm. A smaller emphasis was placed on the efficiency so that the speaker would have a diaphragm surface area and excursion that is comparable with cone-type speakers.