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CHOOSING THE RIGHT
CROWN MICROPHONE
There's a wide variety of Crown microphones to
choose from. This guide will help you select the
microphones best-suited for your applications.
Transducer Type
Condenser or Dynamic
In a dynamic microphone, a coil of wire attached to a
diaphragm is suspended in a magnetic field and
generates an electrical signal similar to the incoming
sound wave.
In a condenser microphone, a diaphragm and an
adjacent metallic disk (backplate) are charged to form
two plates of a capacitor. Sound waves striking the
diaphragm vary the spacing between the plates; this
varies the capacitance and generates an electrical
signal similar to the incoming sound wave.
The diaphragm and backplate can be charged either
by an externally applied voltage, or by a permanently
charged electret material in the diaphragm or on the
backplate.
Because of its lower diaphragm mass and higher
damping, a condenser microphone responds faster
than a dynamic microphone to rapidly changing
sound waves (transients).
Dynamic microphones offer good sound quality, are
especially rugged, and require no power supply.
Condenser microphones require a power supply to
operate internal electronics, but generally provide a
clear, detailed sound quality with a wider, smoother
response than dynamics.
Boundary or Free Field
Boundary microphones are meant to be used on large
surfaces such as stage floors, piano lids, hard-surfaced
panels, or walls. Boundary mics are specially designed
to prevent phase interference between direct and
reflected soundwaves, and have little or no off-axis
coloration. Free-field microphones are meant to be
used away from surfaces, say for up-close miking.
Crown Pressure Zone Microphones (PZMs) and
Phase Coherent Cardioids (PCCs) are boundary
microphones; Crown GLMs, CMs and LMs are
free-field microphones.
Polar Patterns
Omnidirectional or Unidirectional
Omnidirectional microphones (also called pressure
microphones) are equally sensitive to sounds coming
from all directions. Unidirectional microphones (also
called pressure gradient microphones) are most
sensitive to sounds coming from one direction - in
front of the microphone.
Three types of unidirectional patterns are the car-
dioid, supercardioid, and hypercardioid pattern. The
cardioid pattern has a broad pickup area in front of
the microphone. Sounds approaching the side of the
mic are rejected by 6 dB; sounds from the rear (180˚
off-axis) are rejected 20 to 30 dB. The supercardioid
rejects the side sounds by 8.7 dB, and rejects sound
best at two "nulls" behind the microphone, 125˚ off-
axis.
The hypercardioid pattern is the tightest pattern of the
three (12 dB down at the sides), and rejects sound
best at two nulls 110˚ off-axis. This pattern has the
best rejection of room acoustics, and provides the
most gain-before-feedback from the main sound
reinforcement speakers.
Choose omnidirectional mics when you need:
All-around pickup.
Pickup of room acoustics.
Extended low-frequency response.
Low handling noise.
Low wind noise.
No up-close bass boost.
Choose unidirectional mics when you need:
Selective pickup.
Rejection of sounds behind the microphone.
Rejection of room acoustics and leakage.
More gain-before-feedback.
Up-close bass boost (proximity effect).
An omnidirectional boundary microphone (such as
PZM) has a half-omni or hemispherical polar pattern.
A unidirectional boundary microphone (such as a
PCC-160) has a half-supercardioid polar pattern. The
boundary mounting increases the directionality of the
microphone, thus reducing pickup of room acoustics.
Frequency Response
Bright or Flat
A bright frequency response tends to have an empha-
sized or rising high-frequency response, which adds
clarity, brilliance, and articulation. A flat frequency
response tends to sound natural. Microphone place-
ment also has a major effect on the recorded tonal
balance. With loud guitars, amps and drums, a mic
with rising highs or presence peak tends to sound
natural; a flat-response mic tends to sound dull.
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