Dynamic Microphone

What Is a Dynamic Microphone?

From the early days of radio and broadcasting, dynamic microphones played a significant role in producing high-quality sound. Dynamic microphones are microphones that convert sound into an electrical signal using electromagnetism. The construction of a dynamic mic is quite simple. It is similar to a loudspeaker but is much lighter and more delicate, as it has to respond to much lower pressure levels and be light enough to react to higher frequencies without offering any real mechanical resistance. There are two types of dynamic microphones from which we distinguish coil and ribbon-based dynamic microphones.

Coil Dynamic Microphone

Generally, a coil-based dynamic microphone will have a cone with a coil at its end. The coil is suspended with a permanent magnet. Movement of the coil within the magnetic field causes an electrical current. It corresponds to the sound wave, moving the coil by pressure. The very low output from the coil can then be fed into a microphone amplifier, which is lifted at a level to produce a line-level signal that we can hear. Electrical or acoustical means from the rear of the microphone usually alter the directional pattern of the microphone. The coil-based microphones are often preferred for stage use because they are sturdy and do not require external power. In the studio, engineers usually prefer condensers or, in some cases, ribbon microphones. They are less robust but offer superior sound reproduction.

Ribbon Dynamic Microphone

Ribbon microphones work by the same basic principle of electromagnetic induction. However, a ribbon transducer uses a narrow strip of extremely thin aluminum foil instead of a membrane and a coil. In other words, the membrane is the electrical conductor moving inside the magnetic gap. Such a thin piece of aluminum ribbon is much lighter than a membrane with a coil of copper wire. A ribbon transducer is, therefore, able to follow the movements of the sound waves more accurately than a moving coil capsule. Ribbon mics are very fragile.

Consequently, you must treat them with great care. Another drawback is the limitation of the treble response of most ribbon mics. Today, engineers and producers use ribbon mics for special applications. For example, if the extended top end is not required, like for guitar cabinets, or not wanted, e.g., to tame overly bright brass instruments.  

The Range

The range covered by dynamic microphones is generally the same as that of their capacitor counterparts. However, they usually have a lower sensitivity and are more susceptible to outside electrical or inductional interference. They are much more robust and can stand heavy handling in the studio and on location. Dynamic microphones have a much better capability to withstand high amplitudes of sound levels. They generally have a smooth response. It is a fairly universal choice where hand microphones are concerned. Also, producers often use them for mixing the drums and brass sections of brass bands and modern dance music bands. Here, they perform very well. Moreover, it is not unusual to see dynamic microphones as part of a classical music recording rig.