Description
The AT857AMa is a wide-range condenser
microphone designed for quality sound rein-
forcement, professional recording, television,
and other demanding sound pickup applications.
Standing 12.21" above the mounting surface,
its small-diameter alternating gooseneck
design permits highly flexible positioning
while maintaining a smooth, well-contoured
appearance. The AT857AMLa is a 19" version
of this microphone.
Supplied as a cardioid, the AT857AMa easily
accepts interchangeable elements to permit
selection of angle of acceptance from 100° to
360°. The following optional elements are
available from an authorized Audio-Technica
dealer or the A -T service department:
AT853H-ELE hypercardioid, AT853O-ELE
omnidirectional, AT853SC-ELE subcardioid.
The microphone features a 9.8' (3.0 m)
permanently-attached miniature cable with a
3-pin TA3F output connector. It can be pow-
ered from an external 9V to 52V DC phantom
power supply or from a 1.5V AA battery.
Current demands are so low that a premium
battery will provide about 1200 hours of
continuous use. A built-in 3-position switch
on the power module allows selection of off,
on/flat response or on/low-roll-off.
Audio -Technica design engineers have
utilized the newest low-mass technology in
the quest for superior performance. The
permanent charge is now on the fixed back
plate, rather than the moving element. With
A-T fixed charge “back plate” construction, a
gold-vaporized diaphragm just 2 microns
thick (or about 0.000079") can be used. This
reduces moving mass, thus improving
frequency response and transient response
while reducing distortion.
The microphone element is enclosed in a
rugged housing with a low-reflectance black
finish. A
5
/
8
"-27 threaded flange allows the
microphone to mate with the threads of a
standard microphone desk or floor stand. A
5
/
8
"-27 threaded stud is also provided so it can
be secured to a permanent mounting surface.
Installation and Operation
To install the battery, remove the cap from
the top of the power module. Insert the
battery, being certain to observe battery
polarity as marked (+ end toward the cap
release button). For longest battery life, the
switch should remain off except when the
microphone is in use. While standard carbon-
zinc AA batteries will operate the microphone
satisfactorily, alkaline or mercury cells are
preferred for longer service life. Only
“leakproof” batteries should be used. The
battery does not have to be in place to use in
phantom power mode. Phantom power
requires 9V to 52V DC.
Output is low impedance balanced. The
output connector of the power module
mates with XLRF-type cable 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.
The AT8102 two-stage foam windscreen
simply slips over the head of the micro-
phone, effectively reducing wind noise or
“popping” when used extra close.
The small-diameter gooseneck is easy to
manipulate for proper positioning. Heavily
lubricated, it operates smoothly and quietly.
Should the unit become noisy with prolonged
use, apply a light machine oil directly on the
gooseneck area affected.
While a modern condenser microphone is
not unduly sensitive to the environment,
temperature extremes can be harmful. 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.
Architects and Engineers Specifications
The microphone shall be a fixed-charge
condenser with a cardioid polar pattern and a
frequency response of 30 Hz to 20,000 Hz. It
shall be capable of accepting optional inter-
changeable elements for additional polar
patterns. It shall operate from an external 9V
to 52V DC phantom power source or, alterna-
tively, from a 1.5V AA/UM3 battery. Nominal
open-circuit output voltage shall be 6.3 mV
(phantom) or 5.6 mV (battery) at 1 kHz, 1
Pascal. Output shall be low impedance
balanced (200 ohms-phantom, 270 ohms-
battery).
The microphone shall have a permanently-
attached 9.8' (3.0 m) miniature cable,
terminating in a TA3F output connector. The
output connector shall connect to a TB3M
jack on a power module. The included power
module shall house the battery, and contain
an off/on/low-roll-off switch. The power
module shall terminate in a 3-pin XLRM-type
connector.
The microphone shall be a small-diameter
alternating gooseneck design, with 12.21"
(310.2 mm) [19.00" (482.5 mm)] overall length.
Head diameter shall be 0.47" (12.0 mm). The
microphone shall include a
5
/
8
"-27 threaded
flange to mate with the threads of a standard
microphone desk or floor stand. A
5
/
8
"-27
threaded stud shall be provided for perma-
nent installation to a mounting surface. The
microphone weight shall be 3.6 oz (103
grams) [4.6 oz (131 grams)], without cable.
Finish shall be low-reflectance black.
The Audio-Technica AT857AMa [AT857AMLa]
is specified.
AT857AMa
AT857AMLa
CARDIOID
CONDENSER
ADAPTER-
MOUNT
GOOSENECK
MICROPHONES
Frequency Response
LEGEND
Roll-off
12" or more on axis (flat)
Frequency in Hertz
Response in dB
10 dB
20k
10k
5k
2k
1k
500
200
100
50
