AT831b MINIATURE CARDIOID CONDENSER MICROPHONE

AT831b
MINIATURE
CARDIOID
CONDENSER
MICROPHONE
Description
Operation and Maintenance
Architects and Engineers Specifications
The AT831b is a miniature condenser
microphone with a cardioid polar pattern. It
has been designed for hands-free
applications in sound reinforcement systems,
and for use by professional musicians,
especially for pickup of acoustic guitar. The
AT831b provides improved gain before
feedback that normally cannot be achieved
with miniature omnidirectional microphones.
Close-up voice and instrument pickup are
crisp and clean, yet full sounding, while
suppression of background noise is
significantly improved over that of standmounted full-size cardioid microphones.
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 carbonzinc 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.
The microphone shall be a fixed-charge
condenser with a cardioid polar pattern and a
frequency response of 40 Hz to 20,000 Hz. It
shall operate from an external 9V to 52V DC
phantom power source or, alternatively, from
a 1.5V AA / UM3 battery. Nominal opencircuit output voltage shall be 6.3 mV (phantom) or 5.6 mV (battery) at 1 kHz, 1 Pascal.
Output with the included power module shall
be low impedance balanced (200 ohms-phantom, 270 ohms-battery).
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 (about 0.000079") can be used. This
reduces moving mass, thus improving
frequency response and transient response
while reducing distortion.
The microphone may be worn on the person
or attached to a musical instrument. If used
with an instrument, it may be attached by
means of the clothing clip or the special
instrument adapter provided. The power
module may be worn on the belt, utilizing the
belt clip, or located in any convenient place.
An open-pore foam windscreen simply slips
over the head of the microphone, effectively
reducing wind noise or “popping” when
used extra close.
The AT831b can be powered from an external
9V to 52V DC phantom supply or from
an AA/UM3 1.5V battery (supplied). Current
demands are so low that an alkaline
battery will provide about 1200 hours of
continuous use.
Output is low impedance balanced. The
XLRM-type output connector 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.
While a modern condenser microphone is not
unduly sensitive to the environment, temperature 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.
The microphone shall be mountable in an
included instrument adapter or clothing clip.
The microphone shall be 0.98" (25.0 mm)
long with a diameter of 0.39" (10.0 mm). The
microphone weight shall be 0.1 oz (2.8
grams). Finish shall be low-reflectance black.
The Audio-Technica AT831b is specified.
Frequency Response
10 dB
50
100
200
500
1k
2k
Frequency in Hertz
LEGEND
12" or more on axis
Roll-off
5k
10k
20k
Response in dB
The microphone element is enclosed in a
rugged housing with low-reflectance finish.
Internal construction is designed to minimize
handling and clothing noise. A 6' (1.8 m)
cable is provided between the microphone
and power module. A built-in 3-position
switch on the power module allows selection
of off, on/flat response, or on/low-roll-off. An
AT8417 clothing clip and AT8444
guitar adapter are provided, as well as an
accessory AT8116 windscreen. The
microphone is well protected by a speciallydesigned carrying case.
The microphone shall have a permanentlyattached 6' (1.8 m) miniature cable between
the microphone and power module. The
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.
AT831b
AT831b SPECIFICATIONS†
ELEMENT
Fixed-charge back plate
permanently polarized condenser
Cardioid (Unidirectional)
40 -20,000 Hz
80 Hz, 18 dB/octave
–44 dB (6.3 mV) re 1V at 1 Pa*
–45 dB (5.6 mV) re 1V at 1 Pa*
200 ohms
270 ohms
135 dB SPL, 1 kHz at 1% T.H.D.
121 dB SPL, 1 kHz at 1% T.H.D.
106 dB, 1 kHz at Max SPL
92 dB, 1 kHz at Max SPL
65 dB, 1 kHz at 1 Pa*
Off, on-flat, on-roll-off
Use only “leakproof” AA/UM3 1.5V battery
0.4 mA typical
1200 hours (alkaline battery)
9-52V DC, 2 mA typical
Polar Pattern
POLAR PATTERN
FREQUENCY RESPONSE
LOW-FREQUENCY ROLL-OFF
OPEN CIRCUIT SENSITIVITY
0
30
330
300
60
90
270
240
120
150
210
180
SCALE IS 5 DECIBELS PER DIVISION
LEGEND
200 Hz
1 kHz
5 kHz
8 kHz
XLRM-Type Plug Wiring
Low Impedance Balanced
PHANTOM
BATTERY
IMPEDANCE
PHANTOM
BATTERY
MAXIMUM INPUT SOUND LEVEL PHANTOM
BATTERY
DYNAMIC RANGE (TYPICAL)
PHANTOM
BATTERY
SIGNAL-TO-NOISE RATIO1
SWITCH
BATTERY TYPE
BATTERY CURRENT
BATTERY LIFE
PHANTOM POWER REQUIREMENTS
WEIGHT (LESS CABLE AND ACCESSORIES)
MICROPHONE
POWER MODULE
DIMENSIONS
MICROPHONE
POWER MODULE
0.1 oz (2.8 grams)
5.2 oz (147 grams)
0.98" (25.0 mm) long, 0.39" (10.0 mm) dia.
3.27" (83.0 mm) H x 2.48" (63.0 mm) W x
0.87" (22.0 mm) D, not including clip
Integral 3-pin XLRM-type
Integral 6' (1.8 m), permanently attached
between microphone and power module
AT8417 clothing clip; AT8444 instrument adapter;
AT8530 power module; AT8116 windscreen;
battery; protective carrying case
OUTPUT CONNECTOR (POWER MODULE)
CABLE
ACCESSORIES FURNISHED
In the interest of standards development, A.T.U.S. offers
full details on its test methods to other industry
professionals on request.
* 1 Pascal = 10 dynes/cm2 = 10 microbars = 94 dB SPL
1 Typical, A-weighted, using Audio Precision System One.
†
1
/4 " Phone Plug Wiring
Low Impedance Unbalanced
RED WIRE
WHITE WIRE
Optional Accessories:
Dimensions
TIP
SLEEVE
SHIELD
0.98"
25.0 mm
AT8530 Power Module Dimensions
0.87"
22.0 mm
2.48"
63.0 mm
Push Button
To Release Cap
0.39"
10.0 mm
PUSH
3.27"
83.0 mm
• CP8201 line matching transformer
(Lo-Z to 50,000 ohms).
• AT8202 adjustable in-line attenuator for
use with balanced Lo-Z microphones.
• AT8314 2-conductor, shielded, vinyl-jacketed,
broadcast-type cable with XLRF-type
connector at microphone end, XLRM-type
connector at equipment end. Available in
10', 20', 25', 30', 50' & 100' lengths.
• AT8412 double clothing clip.
• AT8414 tie tac.
• AT8438 stand adapter.
• CP8506 four-channel 48V phantom
power supply (AC powered).
• AT8801 single-channel 48V phantom power
supply (AC powered).
SWITCH
POWER MODULE
audio-technica
MADE IN JAPAN
Roll-off
Flat
Off
One-Year Limited Warranty
OFF
Audio-Technica microphones and accessories purchased in the U.S.A. are warranted for one year from date of purchase by
Audio-Technica U.S., Inc. (A.T.U.S.) to be free of defects in materials and workmanship. In event of such defect, product will
be repaired promptly without charge or, at our option, replaced with a new product of equal or superior value if delivered to
A.T.U.S. or an Authorized Service Center, prepaid, together with the sales slip or other proof of purchase date.
Prior approval from A.T.U.S. is required for return. This warranty excludes defects due to normal wear, abuse, shipping
damage, or failure to use product in accordance with instructions. This warranty is void in the event of unauthorized repair
or modification.
For return approval and shipping information, contact the Service Department, Audio -Technica U.S., Inc.,
1221 Commerce Drive, Stow, Ohio 44224.
Except to the extent precluded by applicable state law, A.T.U.S. will have no liability for any consequential, incidental,
or special damages; any warranty of merchantability or fitness for particular purpose expires when this warranty
expires.
This warranty gives you specific legal rights, and you may have other rights which vary from state to state.
Outside the U.S.A., please contact your local dealer for warranty details.
Audio-Technica U.S., Inc., 1221 Commerce Drive, Stow, Ohio 44224
Audio-Technica Limited, Old Lane, Leeds LS11 8AG England
Form No. 0310-0764-07-B/W
© 1998 Audio-Technica U.S., Inc. Printed in U.S.A.