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unipoint
®
microphones
Omnidirectional Condenser Boundary Microphone
U851RO
Features
• PivotPoint
®
rotating output connector allows cable to exit
from either the rear or the bottom of the microphone
• Small-diameter UniPoint omnidirectional capsule near
boundary eliminates phase distortion and delivers clear,
high-output performance
• Superior off-axis rejection for maximum gain before feedback
• UniGuard
®
RFI-shielding technology offers outstanding rejection
of radio frequency interference (RFI)
• Self-contained electronics eliminate need for external
power module
• UniSteep
®
lter provides a steep low-frequency attenuation
to improve sound pickup without affecting voice quality
• Available interchangeable elements permit angle of acceptance
from 100° to 360°
• Heavy die-cast case and non-slip silicon foam bottom pads
minimize coupling of surface vibration to the microphone
• Low-prole design with low-reectance nish for minimum
visibility
U851RO Description
The U851RO is a wide-range condenser microphone with an
omnidirectional polar pattern. It is designed for surface-mount
applications such as high-quality sound reinforcement, conferencing,
professional recording, television and other demanding sound pickup
applications.
The microphone requires 11V to 52V phantom power for operation.
The microphone is equipped with UniGuard
®
RFI-shielding technology,
which offers outstanding rejection of radio frequency interference (RFI).
The microphone’s omnidirectional polar pattern provides a 360° angle of
acceptance (omni in hemisphere above mounting surface). Additional
interchangeable elements with cardioid (120°) and hypercardioid (100°)
pickup patterns are available.
The microphone includes a 7.6 m (25') output cable terminating in special
TA3F-type and XLRM-type connectors designed to optimize RFI
immunity. The output of the microphone is a TB3M-type connector. The
microphone is equipped with Audio-Technica's unique PivotPoint
®
rotating
output connector.
A switch permits choice of at response or low-frequency roll-off (via
integral 80 Hz high-pass UniSteep
®
lter) to help control undesired
ambient noise.
The microphone's heavy die-cast case and non-slip silicon foam
bottom pads minimize coupling of surface vibration to the microphone.
The microphone includes a soft protective pouch and features a low-
reectance black nish.
Installation and Operation
The U851RO requires 11V to 52V phantom power for operation.
Output 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.
The microphone should be placed on a at, unobstructed mounting
surface. The sound source should not be below the plane of the
mounting surface.
An integral 80 Hz high-pass UniSteep
®
lter provides easy switching
from a at frequency response to a low-end roll-off. The roll-off position
reduces the pickup of low-frequency ambient noise (such as trafc, air-
handling systems, etc.), room reverberation and mechanically coupled
vibrations. To engage the UniSteep
®
lter, slide the switch toward the
“bent” line.
The microphone’s PivotPoint
®
rotating output connector allows the cable
to exit from either the rear or the bottom of the microphone without the
need for tools or disassembly.
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. Audio-Technica offers a crimp tool (ATCT) and RFI shields
that enable you to shorten the cable and correctly reinstall the connector
while maintaining the highest level of RFI immunity.
Note: Placing any object on a surface (such as a conference table) before
its nish is fully cured may result in damage to the nish.
Architect’s and Engineer’s Specications
The microphone shall be a xed-charge condenser designed for use
in surface-mount applications. It shall have an omnidirectional polar
pattern in the hemisphere above the mounting surface and a frequency
response of 30 Hz to 20,000 Hz. It shall be capable of accepting optional
interchangeable elements for additional polar patterns. The microphone
shall operate from an external 11V to 52V DC phantom power source.
It shall be capable of handling sound input levels up to 132 dB with
a dynamic range of 111 dB. Nominal open-circuit output voltage shall
be 28.2 mV at 1V, 1 Pascal. Output shall be low impedance balanced
(200 ohms). It shall offer outstanding rejection of radio frequency
interference (RFI).
The microphone shall incorporate self-contained electronics, eliminating
the need for an external power module. A 7.6 m (25') miniature output
cable with TA3F-type to XLRM-type connectors shall be supplied. The
output of the microphone shall be a TB3M-type connector. The microphone
shall include a switch to permit choice of at response or 80 Hz low-
frequency roll-off.
The microphone shall be equipped with an integral rotating output
connector that allows the cable to exit from either the rear or the bottom
of the microphone without the need to disassemble the microphone or
use tools to change the cable exit location.