Audio Technica UniPlate AT891R Product Information

Description

The AT891R is a wide-range condenser
microphone with an hemi-cardioid (half-space
cardioid) polar pattern. It was designed for
surface-mount applications in high-quality
sound reinforcement, conferencing and other
demanding sound pickup situations. Its small
size makes the AT891R suitable for use in
applications where minimum visibility is
required.

The AT891R features a touch-sensitive on/off
switch offering three choices of switching
modes: on/off, momentary on and momentary
off. A switch located on the bottom of the
microphone selects the desired mode. A red
LED on the unit indicates when the micro­phone is “on.”

Positioning a properly designed miniature
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-to­noise ratio. Phase distortion due to reflected
sound energy from the boundary itself is
eliminated.

The AT891R can be powered from any external
11V to 52V DC phantom power supply. A
switch on the bottom of the unit permits
choice of flat response or low-frequency roll­off to help control undesired ambient noise.
A 25' (7.6 m) shielded cable with TA3F and
XLRM-type connectors is provided for use
between the microphone and electronics
inputs.

The microphone is enclosed in a rugged
case and protected by two layers of perforated
steel. The rubber non-slip bottom pad
minimizes mechanical coupling of surface
vibrations to the microphone. The low-profile
housing has a low-reflectance black finish.

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 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 larger
dimension of the mounting surface. The
sound source should not be below, or higher
than 60˚ above, the plane of the mounting
surface.

The AT891R requires 11-52V phantom power
which operates the microphone and switch
circuitry. The electronics in the microphone
take up to 30 seconds to stabilize after

power is applied; during this start-up period,
some thumps or other sonic disturbances
may be heard upon switching if the system is
“live.”

A touch-sensitive on/off switch on the
AT891R offers three choices of switching
modes. A switch located on the bottom of
the microphone selects the desired mode.

TOUCH ON/OFF:

Touch the on/off switch

once to turn mic on, touch again to turn off.

MOM. (Momentary) ON:

Mic is on only
while the switch is being touched (“press to
talk”).

MOM. OFF:

Mic is off only while the
switch is being touched (“press to mute”
function). The red LED on the top of the unit
indicates when the microphone is “on.”

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
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. 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 unidirectional polar
pattern designed for use in surface-mount
boundary applications. The frequency
response shall be 30 Hz to 10,000 Hz. The
microphone shall operate from an external
11V 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).

The microphone shall have a touch-sensitive
switch that may be set for any of three
switching modes: on/off, momentary on,
momentary off. The microphone shall include
a switch for low-frequency roll-off.

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 2.87" (73.0 mm) and a maximum
length of 4.33" (110.0 mm). Weight shall be

2.6 oz (74 grams). The microphone shall be
housed in a rugged case with a two-layer
perforated steel grille. Finish shall be low­reflectance black.

The Audio-Technica AT891R is specified.

AT891R

UNIDIRECTIONAL
CONDENSER
BOUNDARY
MICROPHONE
WITH SWITCH

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

200100

50

60°

IDEAL
WORKING
ANGLE

200 Hz

1 kHz
5 kHz
8 kHz

LEGEND

SCALE IS 5 DECIBELS PER DIVISION

90

60

120

30

150

210

240

270

300

330

180

0

AT891R

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. 0310-0861- 00-B/W P51084 © 1997 Audio-Technica U.S., Inc. Printed in U.S.A.

21.5 mm

0.85"

2.87"

73.0 mm

4.33"

110.0 mm

1.89"

48.0 mm

TOUCH SWITCH

LED

AT891R SPECIFICATIONS

†

ELEMENT Fixed-charge back plate

permanently polarized condenser

POLAR PATTERN Half-cardioid (cardioid in hemisphere above

mounting surface)

FREQUENCY RESPONSE 30-10,000 Hz
LOW-FREQUENCY ROLL-OFF 80 Hz, 12 dB/octave
OPEN CIRCUIT SENSITIVITY –33 dB (22.4 mV) re 1V at 1 Pa*
IMPEDANCE 200 ohms
MAXIMUM INPUT SOUND LEVEL 123 dB SPL, 1 kHz at 1% T.H.D.
DYNAMIC RANGE (TYPICAL) 93 dB, 1 kHz at Max SPL
SIGNAL-TO-NOISE RATIO

1

64 dB, 1 kHz at 1 Pa*

SWITCHES Touch-sensitive control: on/off

Mode selection: touch on/off, momentary on,
momentary off
Flat response, low-roll-off

PHANTOM POWER REQUIREMENTS 11-52V DC, 4 mA typical
WEIGHT 2.6 oz (74 grams)
DIMENSIONS 2.87" (73.0 mm) max width,

4.33" (110.0 mm) max length,

0.85" (21.5 mm) height

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

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

†

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).

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.