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U851A
CARDIOID CONDENSER BOUNDARY MICROPHONE
• UniSteep
®
filter provides a steep low-frequency attenuation to
improve sound pickup without affecting voice quality
• Small-diameter UniPoint capsule near boundary eliminates phase
distortion and delivers clear, high-output performance
• Heavy die-cast case and non-slip silicon foam bottom pads
minimize coupling of surface vibration to the microphone
• Low-profile design with low-reflectance black finish for minimum
visibility
• Operates on battery or phantom power
The U851A requires 11-52V DC phantom power or a 1.5V AA
battery for operation. A battery need not be in place for phantom
power operation.
Battery installation: Remove the cap from the top of the power
module. Insert a fresh 1.5V AA battery ("+" end toward the cap
release button), then reassemble the power module. Alkaline
batteries are recommended for longest life. Remove the battery
during long-term storage.
Supplied as a cardioid, the U851A accepts interchangeable
elements to permit selection of angle of acceptance from 100° to
360°.
The microphone should be placed on a flat,
unobstructed mounting surface, with the front
of the microphone facing the sound source.
60°
The sound source should not be below, or
IDEAL
WORKING
higher than 60° above, the plane of the
ANGLE
mounting surface.
Output from the power module's XLRM-type connector is low
impedance (Lo-Z) balanced. The signal appears across Pins 2 and
3; Pin 1 is ground (shield). Output phase is "Pin 2 hot" – positive
acoustic pressure produces positive voltage at Pin 2.
An integral 80 Hz high-pass UniSteep
from a flat frequency response to a low-end roll-off. The
roll-off position reduces the pickup of low-frequency ambient noise
(such as traffic, air-handling systems, etc.), room reverberation and
mechanically coupled vibrations.
Avoid leaving the microphone in the open sun or in areas where
temperatures exceed 110° F (43° C) for extended periods.
Extremely high humidity should also be avoided.
NOTE: Audio-Technica has developed a special RFI-shielding
mechanism, which is an integral part of the connectors in the
UniPoint line. If you remove or replace the connector, you may
adversely affect the unit's RFI immunity.
NOTE: Placing any object on a surface (such as a conference table)
before its finish is fully cured may result in damage to the finish.
• Designed for surface-mount
applications such as high-
quality sound reinforcement,
professional recording,
television, conferencing and
other demanding sound pickup
situations
• PivotPoint
™
rotating output
connector allows cable to exit
from either the rear or the
bottom of the microphone
• Superior off-axis rejection for
maximum gain before
feedback
• UniGuard
™
RFI-shielding
technology offers outstanding
rejection of radio frequency
interference (RFI)
®
filter provides easy switching
U851A SPECIFICATIONS
†
ELEMENT
POLAR PATTERN
FREQUENCY RESPONSE
LOW FREQUENCY ROLL-OFF
OPEN CIRCUIT SENSITIVITY
(Phantom / Battery)
IMPEDANCE (Phantom / Battery)
MAXIMUM INPUT SOUND LEVEL
(Phantom / Battery)
DYNAMIC RANGE (typical)
(Phantom / Battery)
SIGNAL-TO-NOISE RATIO
1
PHANTOM POWER
REQUIREMENTS
BATTERY TYPE
BATTERY CURRENT / LIFE
SWITCH
WEIGHT
MICROPHONE
POWER MODULE
DIMENSIONS
MICROPHONE
POWER MODULE
OUTPUT CONNECTOR
(power module)
CABLE
OPTIONAL INTERCHANGEABLE
ELEMENTS
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 /cm
= 10 microbars = 94 dB SPL
2
1
Typical, A-weighted, using Audio Precision System One.
Specifications are subject to change without notice.
Polar Pattern
LEGEND
SCALE IS 5 DECIBELS PER DIVISION
LEGEND
200 Hz
1 kHz
5 kHz
8 kHz
Audio-Technica U.S., Inc., 1221 Commerce Drive, Stow, Ohio 44224
Audio-Technica Limited, Old Lane, Leeds LS11 8AG England
www.audio-technica.com
P51701
©2005 Audio-Technica U.S., Inc.
Fixed-charge back plate
permanently polarized condenser
Half-cardioid
(cardioid in hemisphere above
mounting surface)
30-20,000 Hz
80 Hz, 18 dB/octave
–40 dB (10.0 mV) /
–41 dB (8.9 mV) re 1V at 1 Pa*
200 ohms / 270 ohms
133 dB / 123 dB SPL,
1 kHz at 1% T.H.D.
111 dB / 101 dB,
1 kHz at Max SPL
72 dB, 1 kHz at 1 Pa*
11-52V DC, 2 mA typical
1.5V AA/UM3
0.4 mA / 1200 hours typical
(alkaline)
Off, on-flat, on-roll-off
8.6 oz (244 g)
4.9 oz (139 g)
4.25" (108.0 mm) long,
3.31" (84.0 mm) maximum width,
0.91" (23.0 mm) height
3.31" (84.0 mm) H x
2.48" (63.0 mm) W x
0.87" (22.0 mm) D
Integral 3-pin XLRM-type
25.0' (7.6 m) long (permanently
attached to microphone), 0.13"
(3.2 mm) diameter, 2-conductor,
shielded cable with TA3F-type
connector
UE-H hypercardioid (100°);
UE-O omnidirectional (360°)
AT8531 power module; battery;
soft protective pouch
Frequency Response
Frequency in Hertz
12" or more on axis
Roll-off
Printed in U.S.A.
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