Specifications

The construction of a condenser microphone must
include some provision for maintaining the electrical
charge. An electret condenser microphone has a
permanent charge, maintained by a special material
deposited on the backplate or on the diaphragm. Other
types are charged by means of an external power source.
All condensers contain additional circuitry to match
the electrical output of the element to typical microphone
inputs. This requires that all condenser microphones be
powered: either by an internal battery or by phantom
power, which is a method of supplying power to a
microphone through the microphone cable. There are two
potential limitations of condenser microphones due to the
additional circuitry. First, the electronics produce a small
amount of noise. Second, there is a limit to the maximum
signal level that the electronics can handle. Good
condenser designs, however, have very low noise levels
and are also capable of very wide dynamic range.
Condenser microphones are more complex than
dynamics and tend to be somewhat more costly. However,
condensers can readily be manufactured with higher
sensitivity and can provide a smoother, more natural
sound, particularly at high frequencies. Flat frequency
response and extended frequency range are much easier
to obtain in a condenser. In addition, condenser
microphones can be made very small physically without
significant loss of performance.
The decision to use a condenser or dynamic
microphone depends not only on the sound source and
signal destination, but on the physical setting as well. From
a practical standpoint, if the microphone will be used in a
demanding application such as an audience microphone
that is passed around or for outdoor use, a dynamic
microphone is the better choice. In a more controlled
environment, like a boardroom, auditorium, or courtroom,
a condenser microphone might be preferred, especially
when the highest sound quality is desired.
2) Frequency Response:
How does the microphone sound?
The frequency response of a microphone is defined by
the range of sound (from lowest to highest frequency) that
it can reproduce, and by its variation in output within that
range. It is the frequency response that determines the
basic “sound” of the microphone. The two general types of
frequency response are flat and shaped. These terms refer
to the graphical representation of frequency response or
response curve.
A microphone that provides a uniform output at every
audible frequency will have a frequency response graph
that is an even, flat line. This is said to be a flat response.
This means that the microphone reproduces all of the
sound within its frequency range with little or no variation
from the original sound. In addition, flat response
microphones typically have an extended frequency range,
i.e., they can reproduce very high and/or very low frequen-
cies as well. Wide range, flat response microphones have a
natural, “uncolored” sound.
By contrast, a microphone with a shaped response
will have a frequency response graph with a varying line
with specific peaks and dips. This shows that the
microphone is more sensitive to certain frequencies than
to others, and often has a more limited frequency range.
A shaped response is usually designed to enhance the
sound of a particular source in a particular application,
while at the same time minimizing the pickup of certain
unwanted sounds. Shaped response microphones each
have a “characteristic” sound.
Flat frequency response
Shaped frequency response
10
Audio Systems Guide for
MEETING FACILITIES