||This article includes a list of references, related reading or external links, but its sources remain unclear because it lacks inline citations. (October 2012)|
An electrodynamic loudspeaker therefore has two coils:
- The voice coil common to all dynamic loudspeakers, positioned in the air gap between the pole pieces, the motion of which moves the loudspeaker cone.
- A fixed field coil which together with its magnetic core replaces the permanent magnet of other dynamic loudspeakers.
The first electrodynamic loudspeakers were produced in the 1930s, to address the problem that strong permanent magnets of the time were extremely heavy. A compromise was therefore necessary between loudspeaker efficiency, which required the strongest possible magnet, and weight. The use of a strong but relatively light electromagnet solved this problem.
While now uncommon, electrodynamic loudspeakers were once common in top quality mantel radios and similar domestic audio applications, particularly in the post-war period of World War II. In these appliances the field coil of the loudspeaker was also used as the main or only filter choke in the high tension power supply to the valve anodes.
- Definition at answers.com
- Replacing an Electrodynamic Loudspeaker with a Permanent Magnet Loudspeaker deals with the use of the field coil as a filter choke
- Shindo labs field coil loudspeakers
|This electronics-related article is a stub. You can help Wikipedia by expanding it.|
|This history article is a stub. You can help Wikipedia by expanding it.|