Microphones, whether you know it or not, are essentially transducers, meaning they convert one form of energy into another. Microphones take acoustical energy and convert it into electrical, but the way this process happens changes depending on which type of microphone you’re using. Here’s a closer look at the three main kinds of microphones, and how they convert live sound into electrical signals:
In dynamic microphones (aka moving-coil microphones), a coil of wire surrounds a magnet and is connected to a diaphragm which vibrates in response to incoming sound waves. When sound waves hit the diaphragm, the coil oscillates back and forth past the magnet, generating a current which creates the audio signal.
If you’ve ever been to a concert, you’re probably already familiar with dynamic microphones. Due to their simple design, they are incredibly rugged, unphased by extreme temperature or humidity, and essentially incapable of being overloaded. Of the three main types of mics, dynamics tend to be the least sensitive, most durable, and serve as versatile workhorse mics for a wide array of applications.
The capsule of a condenser microphone (aka capacitor microphone) is constructed of a thin, electrically conductive diaphragm in close proximity to a solid metal plate. The diaphragm moves when sound waves hit it and as the distance between the diaphragm and backplate changes, the capacitance between them changes as well, generating a signal. This signal is initially too weak to interact with other pieces of gear, so condenser mics make use of active circuitry to amplify the signal to usable levels. Solid state condensers use 48-volt phantom power for this, whereas tube condensers utilize external power supplies.
Condenser microphones tend to be the mics of choice in studio recording applications, and for good reason. Of the three primary microphone types, they generally offer the widest frequency response*, the fastest transient response**, and greatest overall detail.
*Frequency Response – the way a microphone reacts to frequencies
**Transient Response – the way a microphone reacts to transients, which are the high-amplitude, short-duration sounds at the beginning of waveforms (ex. The initial spike of a snare hit)
While ribbon microphones technically fall under the umbrella of dynamic mics, as they also transduce acoustic energy through electromagnetic induction, they are a very different animal than their rugged, moving-coil counterparts. In ribbon microphones, a thin metal ribbon is suspended between the poles of a magnet and generates a current when it vibrates within the magnetic field.
The ribbon serves as both the diaphragm and the transducer element itself, giving you much greater sensitivity and transient response in comparison to standard dynamic mics. However, the trade-off for this increased responsiveness is much greater fragility, as ribbon elements tend to be only a few microns thick and thus are easily damaged if not cared for properly. Strong gusts of wind and blunt force impact from drops and falls can all put your average ribbon mic out of commission.
Overall, ribbon mics usually have a “darker” sound to them, capturing very honest, accurate representations of sound sources rather than flattering or “coloring” them like condensers and dynamics tend to do. By nature of their design, ribbon mics have a figure-eight polar pattern, picking up sound from both the front and back of the ribbon while rejecting from the sides.