Of all modern microphone designs, dynamics are the simplest. They operate on the principle of electromagnetic induction, meaning the physical motion of components within the mic actually generates its output current by moving a suspended coil of conductive wire, the voice coil (Fig. 1), through a magnetic field. When the incoming sound pressure wave displaces the coil, the result is an output voltage proportional to that wave. Dynamics are generally regarded as the rugged workhorses of the audio trade and are thus often found in live sound applications where they will be subjected to extreme conditions and frequent abuse. They are also found in recording studios and are often used on drums and other very loud instruments because they can withstand high sound pressure levels. But ruggedness comes at a price: Most sound engineers agree that moving-coil dynamics don’t sound nearly as good as their ribbon and condenser counterparts – the high mass voice coil, relative to ribbons and condensers, results in diminished transient response, limited and uneven frequency response, and very poor off-axis response.

Fig. 1 – dynamic microphone with voice coil exposed.