| Most
microphones fall into one of two categories: dynamic or condenser.
Dynamic mics require no power source while condenser mics
do. Their operating principles, the different kinds in each
category, and their applications are explained below.
Dynamic microphones
How they work: Dynamic microphones use an
inductive coil connected to a diaphragm and placed within
the field of a permanent magnet. As the diaphragm moves, it
moves the coil, thus varying the voltage the coil produces.
General characteristics: Dynamic mics are
rugged and often have a high SPL capability, internal shockmounting
to allow hand use, and a polar pattern that rejects off-axis
sounds. They tend to be used for live sound applications,
for vocals and instruments, and some are also used for recording.
The Shure SM57 has been both a studio and stage staple for
many years. As a group, dynamic mics are relatively affordable,
and many of the big-name mic manufacturers have economy series
mics that give you great performance for a low price.
Ribbon microphones » Unlike other dynamic
mics, ribbon mics are extremely delicate. They operate by
the same principle as the other dynamic mics, but instead
of a diaphragm, they employ a thin ribbon that vibrates to
vary voltage. Ribbon mics are used in the studio for recording
voices and a broad range of instruments. They soften the sound
and impart a warmth to recorded material. They have high SPL
capabilities and so can be placed very close to a sound source.
Application-specific dynamic mics »
In recent years, microphone manufacturers have begun producing
dynamic microphone models designed for specific instruments.
Here are a few examples:
* Drum microphones » Because drum kits
make so many different sounds, mics have been tailored for
kick drums, snares and toms, and cymbals. Each mic will have
a response range and profile suited to the drum it is used
on. Drum mics are often sold in special packs of four, five,
or more. They usually save you money, are convenient, and
each mic is tailored to its job.
* Horn microphones » These are typically small size,
lightweight, have a frequency response tailored to the instrument,
and employ a special mounting system that attaches to the
horn's bell or body. They move with the horn and thus maintain
a set distance for greater volume consistency. An attached
horn mic also allows the player more freedom to move.
# Bullet microphones » These are used by harp players.
They have a short round casing that can be cupped in the player's
hands along with the harmonica, and their crystal diaphragm
elements produce a distorted sound beloved by blues harp players.
# Wireless microphones » These are essentially the same
as wired microphones with a transmitter added.
Condenser microphones
How they work: In these mics, a thin conductive
diaphragm is located close to a metal plate called a backplate,
creating a capacitor. The capacitor is supplied with a small
electric charge, either from phantom power or from a battery.
When the pressure of soundwaves cause the diaphragm to vibrate,
it changes the distance between it and the backplate, thus
causing variations in the output voltage. This varied output
is the microphone's signal.
General characteristics: Condenser microphones
either have an external power supply, internal batteries,
or use phantom power supplied by the mixer input. These days,
most mixers have phantom power on mic inputs, but if you are
using an older mixer, make sure it has phantom power before
buying a condenser that requires it.
There are many different types of condenser
mics, and most of them are used for recording. A few are used
for live sound applications such as overhead miking of choirs,
pianos, acoustical string instruments, and certain percussion
instruments. Often a condenser is used for overhead cymbal
miking. Here are the main types of condenser microphones:
Roll-off and attenuation switches »
These controls are found on many condenser microphones and
enhance versatility. The roll-off switch alters the frequency
range, usually on the low-end, reducing response or cutting
it off below a certain level. The roll-off is used in live
situations to reduce low-end rumble and to increase amp efficiency.
Many amps don't produce very low frequency sounds but they
use up power trying to. Rolling off the bass keeps the PA
power amp from having to deal with frequencies below its capability.
In recording, rolling off the bass can add clarity. Attenuation
switches alter a mic's sensitivity or volume, padding it so
that a high volume source doesn't overload the mic.
Large-diaphragm condenser microphones »
These are the big recording microphones with diaphragms from
three quarters to an inch in diameter. Usually very sensitive,
they require external power and suspension mounting. Their
large size and need for suspension makes them unsuited for
such applications as miking drum kits where placement is tight,
but they are excellent for recording voices and many instruments.
They often serve as the studio's all-purpose microphone, and
the best can be very expensive. A number of affordable large-diaphragm
condensers have become available in recent years that mimic
the design of the expensive models and work quite well for
nonprofessional recording.
Side address condenser microphones »
These are a type of large condenser mic. They usually have
a wide, flat windscreen over a large diaphragm positioned
horizontally and aimed toward the side at a 90-degree angle.
If the mic is vertical, a singer seems to be addressing the
mic from the side, hence the name.
Dual-diaphragm condensers » Usually
these are side-address mics and have two diaphragms aimed
in opposite directions. They are effective for recording duets
or larger groups, or for room ambience applications. A dual
condenser mic makes it easier to keep two simultaneous sources
balanced than using two single-diaphragm mics.
Tube condenser microphones » These are
the vintage recording mics used in recording and broadcast
studios decades ago. Because they impart a special quality
to recorded material—much like a tube guitar amp colors
the instrument's sound—they are still made and used
in professional studios to this day. They require a dedicated
power supply, and it is the tubes in this power supply that
warm up and color the sound.
Small-diaphragm condenser microphones » These microphones
have a diaphragm that is one-half inch or less in diameter
and are used in many recording applications and a few live
applications as well. They do especially well at reproducing
higher frequency sounds and sound sources that change quickly
in volume or have sudden attack. One common application is
overhead miking of cymbals. Like other condensers, they depend
on phantom power or a battery to operate.
Shotgun microphones » These are condenser
mics with a very narrow and extended polar pattern. They are
often used for broadcasts—at sporting events, for example—because
they excel at picking up specific sound sources from a distance.
Boundary microphones » Boundary mics
are quite versatile, used on podiums, at conferences, and
in the studio. These mics are usually placed on a flat surface—the
floor, ceiling, or wall—which helps gather the sound.
They are good for stereo applications and for general miking
of musical groups.
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Buying Guide | Types
of microphones and their applications
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