Speakers/Microphones

Speakers and microphones convert an alternating electrical signal into physical vibrations in order to create sound, or visa-versa.  Proper magnet design in a speaker/microphone is crucial in ensuring good fidelity. 

An amplified signal current applied to the 'voice coil', attached to the speaker diaphragm, causes an alternating magnetic field at the signal frequency.  This alternating magnetic field interacts with the static magnetic field of the permanent magnet structure to cause movement of the voice coil and speaker cone. Displacement of the diaphragm moves the air in front of the speaker, creating pressure waves, or sound.

If the 'voice coil' is attached to mechanical component, that component will have alternating linear motion and the device is known as a voice coil motor.  Motors of this type are used in many cryocooler applications. 

If DC current is fed to the 'voice coil', the coil will be displaced in proportion to the current.  It is then known as a linear actuator, or a linear transducer.  This type of actuator is used in various types of disk drives.  If the voice coil is attached to a pivot point, its motion will be rotary.  It is then known as a rotary actuator.  These are used in the vast majority of disk drives today.

For further inquiries, please e-mail us at info@dextermag.com -or- call us at:  800-345-4082 (In North America) or +44 (0) 1189 602430 (In Europe).