Audio Technica UniPlate AT871R, UniPlate AT871RW, PN-K321H Product Information

Description

The AT871R is a wide-range condenser micro­phone with a hemi-cardioid (half-space cardioid)
polar pattern. It is useful in surface-mounted
applications such as high-quality sound rein­forcement, professional recording, television,
and other demanding sound pickup applications.

Supplied as a cardioid, the AT871R 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.

Positioning a properly designed miniature
cardioid microphone centrally on a large, flat,
unobstructed surface yields several distinct
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 AT871R is powered from an external 9V
to 52V DC phantom power supply. A 25' (7.6 m)
cable is provided with TA3F and XLRM-type
connectors for use between the microphone
and electronics input.

The microphone element is enclosed in a
rugged die-cast case and protected by two
layers of perforated steel. The combination of
heavy die-cast case and rubber non-slip bottom
pad minimizes mechanical coupling of surface
vibrations to the microphone. The low-profile
housing has a low-reflectance black finish.
The microphone is also available in white as
the AT871RW, with a white-finished micro­phone housing and cable.

Installation and Operation

The symmetry and area of the mounting surface
directly affect the sensitivity of the boundary
microphone at low frequencies. Ideally, the
mounting surface should be circular; however,
square or rectangular surfaces are most often
used. If the mounting surface is rectangular,
the smaller dimension tends to determine
the low-frequency cutoff. The microphone
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.

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.

Architects and Engineers Specifications

The microphone shall be a fixed-charge con­denser with a hemi-cardioid polar pattern
designed for use in surface-mount boundary
applications. The frequency response shall be
30 Hz to 20,000 Hz. The microphone shall
operate from an external 9V to 52V DC
phantom power source. Nominal open-circuit
output voltage shall be 22.4 mV at 1 kHz, 1
Pascal. Output shall be low impedance bal­anced (200 ohms).

A 25' (7.6 m) cable with TA3F to XLRM-type
connectors shall be supplied for connection
between the microphone and electronics
input. The microphone shall have a maximum
width of 4.72" (120.0 mm) and a maximum
length of 5.71" (145.0 mm). Weight shall be

14.6 oz (415 grams). The microphone shall be
housed in a die-cast case with a two-layer
perforated steel grille. Finish shall be low­reflectance black [white].

The Audio-Technica AT871R [AT871RW] is
specified.

Output is low impedance balanced. The bal­anced signal appears across Pins 2 and 3
while the ground (shield) connection is Pin 1.
Output is phased so that positive acoustic

AT871R
AT871RW

UNIDIRECTIONAL
CONDENSER
BOUNDARY
MICROPHONES

Frequency Response

50

LEGEND

500

200100

Frequency in Hertz

12" or more on axis (flat)

2k

1k

5k

10 dB

Response in dB

10k

20k

AT 8 71R/AT871RW SPECIFICATIONS

†

ELEMENT Fixed-charge back plate

permanently polarized condenser

POLAR PATTERN Half-cardioid (cardioid in hemisphere above

mounting surface)

FREQUENCY RESPONSE 30-20,000 Hz
OPEN CIRCUIT SENSITIVITY –33 dB (22.4 mV) re 1V at 1 Pa*
IMPEDANCE 200 ohms
MAXIMUM INPUT SOUND LEVEL 130 dB SPL, 1 kHz at 1% T.H.D.
DYNAMIC RANGE (TYPICAL) 103 dB, 1 kHz at Max SPL
SIGNAL-TO-NOISE RATIO

1

67 dB, 1 kHz at 1 Pa*

PHANTOM POWER REQUIREMENTS 9-52V DC, 2 mA typical
WEIGHT (LESS CABLE) 14.6 oz (415 grams)
DIMENSIONS 4.72" (120.0 mm) max width,

5.71" (145.0 mm) max length,

0.67" (17.0 mm) height

OUTPUT CONNECTOR TB3M-type
CABLE 25' (7.6 m) long, 0.13" (3.2 mm) diameter,

2-conductor, shielded cable with TA3F and
XLRM-type connectors

ACCESSORY FURNISHED Soft protective pouch
OPTIONAL INTERCHANGEABLE ELEMENTS AT853H-ELE hypercardioid (100°)

AT853O-ELE omnidirectional (360°)
AT853SC -ELE subcardioid (170°)

†

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/cm

2

= 10 microbars = 94 dB SPL

1

Typical, A-weighted, using Audio Precision System One.

Optional Accessories:

• 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.

• CP8506 four-channel 48V phantom power
supply (AC powered).

• AT8801 single-channel 48V phantom power
supply (AC powered).

AT871R
AT871RW

Polar Pattern

Dimensions

Audio-Technica U.S., Inc., 1221 Commerce Drive, Stow, Ohio 44224
Audio-Technica Limited, Old Lane, Leeds LS11 8AG England

Form No. 0310-0854 -01-B/W P50878-01 © 1998 Audio-Technica U.S., Inc. Printed in U.S.A.

One-Year Limited Warranty

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.

200 Hz

1 kHz
5 kHz
8 kHz

LEGEND

same as 1 kHz

SCALE IS 5 DECIBELS PER DIVISION

90

60

120

30

150

210

240

270

300

330

180

0

120.0 mm

4.72"

145.0 mm

5.71"

2.76"

70.0 mm

17.0 mm

0.67"