Principle of Operation
In the moving coil microphone, the diaphragm is attached to a light movable coil that generates a voltage as it moves back and forth between the poles of a permanent magnet. In ribbon microphones, a voltage is induced at right angles to both the ribbon velocity and magnetic field direction. As the sound wave causes the ribbon to move, the induced voltage in the ribbon is proportional to the particle velocity in the sound wave. The voltage output of older ribbon microphones is typically quite low compared to a dynamic moving coil microphone and a step-up transformer is used to increase the voltage output and increase the output impedance. Modern ribbon microphones do not suffer from this problem due to improved magnets and more efficient transformers, and have output levels that can exceed typical stage dynamic microphones.
Ribbon microphones were once delicate, and expensive, but modern materials make certain present-day ribbon microphones very durable and may be used for loud rock music and stage use. They are prized for their ability to capture high-frequency detail, comparing very favorably with condenser microphones, which can often sound subjectively "aggressive" or "brittle" in the high end of the frequency spectrum. Due to their bidirectional pick-up pattern, ribbon microphones are often used in pairs to produce the Blumlein Pair recording array. In addition to the standard bidirectional pick-up pattern, ribbon microphones can also be configured to have cardioid, hypercardioid, omnidirectional, and variable polar patterns, although these configurations are much less common.
As many mixers are equipped with phantom power in order to enable the use of condenser microphones, care should be taken when using condenser and ribbon microphones at the same time. If the ribbon microphone is improperly wired, which is not unheard of with older microphones, this capacity can damage some ribbon elements. Improvements in designs and materials have made those concerns largely inconsequential in modern ribbon microphones, however.
Read more about this topic: Ribbon Microphone
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