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PRO
42
MINIATURE UNIDIRECTIONAL
CONDENSER BOUNDARY
MICROPHONE
Frequency in Hertz
Response in dB
10 dB
20k
10k
5k
2k
1k
500
200100
50
LEGEND
12" or more on axis
Frequency Response
pad minimizes mechanical coupling of surface
vibrations to the microphone. The low-profile
housing has a low-reflectance black finish.
Operation and Maintenance
The symmetry and area of the mounting sur-
face directly affect the sensitivity of the
boundary microphone at low frequencies.
Ideally, the mounting surface should be circu-
lar; however, square or rectangular surfaces
are most often used. If the mounting surface
is rectangular, the smaller dimension tends to
determine low-frequency cutoff. The micro-
phone should be centered on the surface and
positioned with the front of the microphone
facing the sound source along the longer
dimension of the mounting surface. The
sound source should not be below, or higher
than 60° above, the plane of the mounting
surface.
Output is low impedance balanced.The output
connector mates with XLRF-type connectors.
The balanced signal appears across Pins 2
and 3, while the ground (shield) connection
is Pin 1. Output is phased so that positive
acoustic pressure produces positive voltage at
Pin 2 in accordance with industry convention.
DC phantom power (9-52 volts) must be
applied equally to Pins 2 and 3, with the
ground for the power supply connected to
Pin 1. This can be provided by a console or
mixer with built-in phantom voltage or with the
addition of an in-line phantom power supply,
such as the recommended Audio-Technica
CP8506 and AT8801 power supplies.
The high sensitivity of the PRO42 ensures
useful output and an excellent match to most
mixer, tape recorder and amplifier inputs. It
will provide undistorted output even in sound
Description
The PRO42 is a wide-range miniature con-
denser microphone with a hemi-cardioid
(half-space cardioid) polar pattern. It was
designed for surface-mounted applications in
high-quality sound reinforcement and other
demanding sound pickup situations. Its small
size makes the PRO42 ideal for use in appli-
cations where minimum visibility is required.
The PRO42 features a 25' (7.6 m) perma-
nently-attached miniature cable with an
XLRM-type connector, which allows it to be
plugged directly into an XLRF-type jack or
cable connector.The unit’s integral electronics
can be powered from any external 9V to 52V
DC phantom power source.
Audio-Technica design engineers have utilized
the newest low-mass technology in the quest
for superior performance. The charge is now
on the fixed back plate, rather than the moving
element.With the A-T fixed-charge “back plate”
construction, a gold-vaporized diaphragm just
2 microns thick (about 0.000079") can be
used.This reduces moving mass substantially,
improving frequency response and transient
response while reducing distortion.
Positioning a properly designed miniature
unidirectional microphone centrally on a large,
flat, unobstructed surface yields several dis-
tinct advantages. Directionality is increased
by 3 dB, promoting enhanced gain before
feedback and further suppression of ambient
noise. Sensitivity is increased for improved
signal-to-noise ratio. Phase distortion due to
reflected sound energy from the boundary
itself is eliminated.
The microphone element is enclosed in a
rugged case and protected by heavy
perforated steel. The rubber non-slip bottom
fields as loud as 134 dB SPL. However, due
to the high sensitivity, in some instances it
may be possible to overload sensitive input
stages. If distortion occurs,
first
check for
input
overload. In such cases, an attenuator
such as the Audio-Technica AT8202 may be
required between the mic and the electronics
input. (Also, many mixers provide “input pad”
switches to reduce mic-input signal levels.)
While a modern condenser microphone is not
unduly sensitive to the environment, tempera-
ture extremes can be harmful. Exposure to
high temperatures can result in gradual and
permanent reduction of the output level.Avoid
leaving the microphone in the open sun or in
areas where temperatures exceed 110° F
(43° C) for long periods of time. Extremely
high humidity should also be avoided.