Basic Microphone Types
Microphones convert varying sound pressure waves—or acoustic energy—into varying electrical voltages that can be translated through P.A. systems and captured on tape or hard-disk recorders. Although there are numerous types of microphones, each of which does this in its own way, the three types most commonly used with instruments and voices are dynamic, ribbon, and condenser microphones.
How They Work: Dynamic microphones utilize a thin plastic diaphragm attached to a fine-wire coil (the voice coil), suspended in a permanent magnetic field. Sound pressure against the diaphragm displaces the voice coil, producing a voltage.
Acoustic Properties: The coil’s relatively large mass results in a comparatively slow response to quiet sounds and quick transients, while at the same time allowing the microphone to withstand greater sound-pressure levels (such as a blaring Marshall or the crack of a snare drum). Dynamic microphones have a fatter and less-nuanced sound than ribbon or condenser types, with punchy mids and less-accurately reproduced highs.
Common Applications: Electric guitar, bass, snare, toms, brass, live vocals.
Classic Examples: Shure SM57, Sennheiser MD42-II.
How They Work: Ribbon microphones are a type of dynamic microphone that captures sound using an ultra-thin, corrugated-aluminum ribbon suspended between the poles of a magnet rather than a voice coil. This is the mic that first made it possible to record soft crooners such as Bing Crosby. Before ribbon mics, vocalists typically had to sing into horn-like devices, and brassy tenors (such as Al Jolson) were reproduced best.
Acoustic Properties: Ribbon microphones are valued for their silky-smooth and highly detailed response. Older models tend to be very fragile, though some newer ones (such as the Royer Labs R-121) can withstand greater sound-pressure levels.
Common Applications: Voice, acoustic instruments.
Classic Example: RCA 44BX.
How They Work: Condenser microphones employ a pair of conducting plates, one stationary and the other a moving plastic diaphragm coated on one side with nickel or gold. A polarizing voltage is applied to the plates, typically from a battery or phantom-power source, creating a varying charge when sound pressure moves the diaphragm. There are both large diaphragm and small diaphragm condenser microphones.
Acoustic Properties: Condenser microphones provide uniform frequency response over an extended range with excellent clarity, transparency, and detail.
Common Applications: Nearly any source, though many small-diaphragm condensers are application-specific (drum overheads, woodwinds, strings, etc.), and large-diaphragm models are particularly desirable as voice and room mics. Large-diaphragm tube condensers are the sound of classic rock and R& vocals.
Classic Examples: Neumann U87 (large diaphragm), Audio-Technica AT4041 (small diaphragm).