moving coil loudspeaker
The plunging-coil loudspeaker is an electrodynamically operating loudspeaker in which a voice coil, to which the diaphragm is attached, is moved in an air gap in a permanent magnetic field.
When a current flows through the coil, it will move in the permanent magnetic field depending on the direction of the current. The current flow in the inductor creates a magnetic field whose lines of force are repelled or attracted by those of the permanent magnet, causing the speaker diaphragm to move. The force with which the voice coil is deflected is a result of the magnetic induction, the conductor length and the current flow. This technique is called the plunger coil technique or piston principle.
Since the voice coil and diaphragm are fixed to each other, the diaphragm also moves, from which the sound wave is released in rhythm with the audio signal. The size of the diaphragm determines the depth of sound that can be radiated. Sounds with high frequencies have small diaphragms, while woofers have large ones, which is related to the detachment of the corresponding wavelengths from the speaker diaphragm.
Such a single loudspeaker, which consists of the speaker basket, the diaphragm with the voice coil centered by the surround and the centering spider in the speaker basket, and the electromagnet, is also called a loudspeaker chassis. The weight of the diaphragm with the voice coil and the restoring force of the surround and the centering coil determine the resonant frequency of the speaker chassis. The surround is the elastic rubber rim that is placed around the diaphragm. The spring force of the surround ensures that the diaphragm is returned to its rest position after deflection. It is made of rubber.