Audio-Technica condenser boundary microphones - Manual

Description

The AT845R is a wide-range condenser

microphone with an omnidirectional polar pattern.
It is designed for unobtrusive table, ceiling or
panel-mounted applications for high-quality
sound reinforcement, teleconferencing, profes-
sional recording, television and other demanding
sound pickup applications.

The AT847R is a similar microphone, with a

unidirectional polar pattern. Positioning a properly
designed miniature unidirectional microphone
centrally on a large, flat, unobstructed surface
yields several distinct advantages. The directivity
factor is greatly increased over a comparable
omnidirectional microphone, thus promoting
enhanced gain before feedback and further
suppressing ambient noise. Sensitivity is increased
for improved signal-to-noise ratio. Phase distortion
due to reflected sound energy from the boundary
itself is eliminated.

Both microphones require 9V to 52V DC

phantom power for operation. The microphones
are enclosed in a heavy-duty die-cast case and
protected by two layers of heavy perforated steel.
The low-profile housing has a low-reflectance
black finish. The microphones are also available
in white, as AT845RW and AT847RW. Isolators
are included with each microphone for applications
where mechanical isolation from the mounting
surface is required.

Installation and Operation

Output is low impedance balanced. The bal-

anced 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.

To mount these microphones in a ceiling or

table top

without the isolators, a

13

⁄

16

" diameter hole

is required. To mount these microphones

with the

isolators, a

15

⁄

16

" hole is required. The isolators can

be placed on either side of the hole for mechanical
isolation from the mounting surface.

The Audio -Technica round mark ( ) on the

AT847 bezel indicates the “front” of the microphone.

While a modern fixed-charge condenser

microphone is not unduly sensitive to the environ-
ment, temperature extremes can be harmful.
Exposure to high temperature 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

AT845R [AT845RW]

The microphone shall be a fixed-charge

condenser with an omnidirectional polar pattern
designed for use in table, ceiling or panel-mount
applications. The frequency response shall be
30 Hz to 20,000 Hz. The microphone shall operate
from an external 9V to 52V phantom power source.
Nominal open-circuit voltage shall be 7.9 mV at
1 kHz, 1 Pascal. Output shall be low impedance
balanced (200 ohms).

AT845R / RW

Omnidirectional

AT847R / RW

Cardioid

Condenser
Boundary
Microphones

The microphone shall have a self-contained

power module with an XLRM-type output connector.

The microphone shall have a diameter of

1.10" (28.0 mm) and a length of 2.72" (69.0 mm).
Weight shall be 2.1 oz (60 grams). The micro-
phone shall be housed in a die-cast case with a
two-layer perforated steel grille. Finish shall be
low-reflectance black [white].

The Audio -Technica AT845R [AT845RW]

is specified.

AT847R [AT847RW]

The microphone shall be a fixed-charge

condenser with a unidirectional polar pattern
designed for use in table-mount applications. The
frequency response shall be 30 Hz to 20,000 Hz.
The microphone shall operate from an external
9V to 52V phantom power source. Nominal open-
circuit output voltage shall be 7.9 mV at 1 kHz,
1 Pascal. Output shall be low impedance
balanced (200 ohms).

The microphone shall have a self-contained

power module with an XLRM-type output connector.

The microphone shall have a maximum

diameter of 1.18" (30.0 mm) and a length of 2.72"
(69.0 mm). Weight shall be 2.2 oz (62 grams).The
microphone shall be housed in a die-cast case
with a two-layer perforated steel grille. Finish shall
be low-reflectance black [white].

The Audio-Technica AT847R [AT847RW]

is specified.

Frequency in Hertz

Response in dB

10 dB

20k

10k

5k

2k

1k

500

200

100

50

LEGEND

12" or more on axis

AT847R Frequency Response

AT845R Frequency Response

Frequency in Hertz

Response in dB

10 dB

20k

10k

5k

2k

1k

500

200

100

50

LEGEND

12" or more on axis