Audio Technica SmartMixer AT-MX381 User manual

SmartMixer® Eight-Channel Automatic Mixer
AT-MX381
Features
• Eight balanced inputs allow use with both mic- and line-level signals
• Each input provides:
- Phantom power (48V), individually selectable
- Individual gain and volume controls
- Gate attenuation (adjustable)
- Low-cut lter (individually selectable via SmartMixer
®
Software)
• An RS232 data port provides a connection point for a PC with
included SmartMixer
®
Software
• Compatible with Crestron
®
and AMX
®
systems
• External control capability enables the SmartMixer
®
to activate
other devices
- Force-On–allows an external contact closure to force its associated
input to turn on
- Force-Off–allows an external contact closure to force its associated
input to turn off
- Control Voltage Out–a voltage appears when the associated input’s
gate opens or turns “on”
• Selectable NOMA (Number of Open Mics Attenuated) circuitry helps
control feedback
• Priority pre-select feature allows priority of each microphone to be
independently assigned
• Last Mic On selectable for continuous room ambiance
• Linking capability for 16 units (up to 128 channels)
• A direct output connection is available for each input
• Equipped with two audio outputs (one balanced, one unbalanced)
to drive amplication systems or other equipment
• Monitor headphone output with level control
• Basic functions are congured via front panel; detailed settings
through SmartMixer
®
Software
• Mounts in a single 19" rack space via integral rack-mount
Description
Audio-Technica’s AT-MX381 SmartMixer® is a microprocessor-controlled,
programmable, automatic-switching eight-channel audio mixer designed
to improve audio quality in broadcast, sound-reinforcement and recording
applications. By keeping the number of open microphones to a minimum,
the mixer reduces background noise, feedback and other distractions,
while providing instant, completely transparent switching between channels.
For use with low-impedance dynamic and condenser microphones
(including wireless microphone systems), as well as with line-level
sources, the AT-MX381 automatically gates microphones on and off for
the best possible audio quality. Each of the AT-MX381 SmartMixer’s eight
balanced inputs provides switchable 48-volt phantom power; attenuation
is also selectable on each input to allow use with line-level signals. A
direct output connection is available for each input, for use with logging
recorders and other devices. To custom-tailor conferencing needs, the
mode of each microphone channel can be independently switched. The
combination of switch settings results in three different modes of priority
selection/operation. A selectable last mic on feature keeps the most
recently used microphone on for continuous room ambiance.
Up to 16 AT-MX381 SmartMixers (a total of 128 channels) can be
daisy-chained via the included Link Cable, for large multi-mic installations.
In a multiple-microphone system, as more microphones are turned on,
the increased system gain can be a potential source of feedback. The
selectable NOMA (Number of Open Microphones Attenuated) feature
helps control feedback by compensating for the increase in system gain.
A built-in algorithm in the AT-MX381 recognizes how many microphones
are “on” and automatically adjusts the system gain accordingly. If
automatic functions are not desired, the AT-MX381 SmartMixer® can
function in manual mode, bypassing the mixer’s automatic switching and
attenuation functions, causing the unit to behave like a conventional mixer.
The AT-MX381 includes two separate external control systems: Individual-
channel contact closures (via DB25 connector) and PC control (via RS232
connector). The RS232 connector can also be used to connect an external
control system (Crestron® or AMX®) using open disclosure communica-
tion protocol to control the SmartMixer.
Architect’s and Engineer’s Specications
The automatic mixer shall be a microprocessor-controlled, programmable,
automatic-switching eight-channel audio mixer. It shall be suitable for
use with low-impedance dynamic and condenser microphones (including
wireless microphone systems), as well as with line-level input sources.
The mixer shall be equipped with eight balanced inputs, each providing
switchable 48-volt phantom power. Independent input trim (for gain set-
ting) and channel level controls shall be provided for each input allowing
the automatic mixer to accept a wide variety of microphone- and line-
level signals. A low-frequency roll-off lter shall be provided on each input
to tailor the sound to minimize the pickup of unwanted mechanical noise.
Each input shall be provided with an input gate/overload indicator to show
channel gate status or input overload. Input and output connections shall
be via standard Phoenix-type connector blocks. Mating connectors shall
be included with the mixer. A direct output connection shall be available
for each input. This connection shall be congurable to output signal
before or after the channel’s gate.
The mixer shall be designed to operate in one of three priority congura-
tions, allowing certain inputs to have priority over other inputs. It shall be
possible to independently congure the setting of each input channel, for
one of the priority modes. Any number of channels can be given priority
over other channels for maximum operational exibility. An adjustable
master threshold control shall be provided to allow for setting the point
at which the gates are triggered. Front panel status indicators shall be
provided showing attenuation status, mic/line input selection and channel
priority mode. A dedicated LED shall indicate manual or automatic mode.
The mixer shall allow for last microphone on operation. In this mode, the
last active microphone shall stay active (on) so that ambient sound is
never muted. The time that the mixer keeps a channel’s gate open shall
be congurable from 0.5 to 3.0 seconds.
The unit shall offer a selectable NOMA (Number of Open Microphones
Attenuated) feature to help control feedback by compensating for the
increase in system gain based on the number of active (open) micro-
phones. The automatic mixer shall offer a manual mode, which bypasses
the mixer’s automatic switching and attenuation functions.
The mixer shall provide external contact closures and logic control
outputs to enable the mixer to interface with external devices for control
and status indication via a standard DB25 connector. An RS232 computer
interface control connector shall be provided for connection of a com-
puter system for conguration and programming. In addition, the RS232
SmartMixer®

AT-MX381
Specications
In the interest of standards development, A.T.U.S. offers full
details on its test methods to other industry
professionals on request.
*Input terminated with 150 ohms, A-weighted,
using Audio Precision System Two
Specications are subject to change without notice.
Audio-Technica U.S., Inc., 1221 Commerce Drive, Stow, Ohio 44224
Audio-Technica Limited, Old Lane, Leeds LS11 8AG England
©2010 Audio-Technica U.S., Inc. audio-technica.com 0001-0225-00
Input impedance
Output impedance
Maximum input level
Maximum output level
Maximum monitor output
Maximum gain
Frequency response
Equivalent input noise
Microphone phantom power
Control voltage out
Power supply
Operating temperature
Dimensions
Weight
connector may be connected to an external control system (Crestron® or
AMX®) using standard open disclosure communication protocol to control
the mixer. Conguration software shall be provided with each automatic
mixer. It shall be possible to congure an entire linked system from one
mixer (master). The software shall be graphical in nature operating on the
standard Windows™ operating system.
Two audio outputs (one balanced, one unbalanced) shall be provided to
drive amplication systems or other equipment. A master output control
shall be provided to set the overall level of the SmartMixer®. An adjust-
able limiter shall be provided on the main output to prevent overdriving.
A front panel headphone jack with level control and an LED output level
indicator shall be provided to monitor the audio output of the mixer.
It shall be possible to select the output indicator function pre or post
master level control.
Up to 16 automatic mixers (a total of 128 channels) may be daisy-chained
for large multi-mic installations. When operating in this way, the output
for all of the linked mixers shall appear at the master mixer in the chain.
Last mic on, NOMA and other conguration settings shall cascade
through the entire chain of linked mixers. Each mixer shall include the
cable for linking units together.
The mixer shall be designed to mount in a standard 19" equipment rack
occupying no more than one rack space. Rack ears shall be integral to the
unit. All system settings shall be possible via front panel controls or soft-
ware programming without having to remove the mixer from the rack.
A security cover shall be available to prevent unauthorized tampering
with front panel controls and it shall be possible to lock out programming
functions via the software or front panel switch sequence. The mixer shall
be designed with a universal internal power supply enabling it to operate
internationally on any global power system. It shall be provided with
proper IEC-type mains power cable specic to its location and an RS232
computer interface cable for programming (North America only).
The Audio-Technica AT-MX381 is specied.
Windows™ is a registered trademark of Microsoft Corporation in the United States
and other countries.
AMX ® is a registered trademark of AMX Corporation.
Crestron® a is registered trademark of Crestron International
8
CHANNEL AUTOMATIC MIXER AT -MX
381
POWER
MIN MAX
LEVEL
MONITOR
GAINLEVEL
MIN MAX
GATE
THRESHOLDLEVEL
MIN MAX
AUTO AT T.
P4 8 /
AT T.
AT T.
+10
LEVEL AT T. P4 8 PRIORI T Y
+6
+3
0
-3
-6
-10
-20
CH
8
CH
7
CH
6
CH
5
CH
4
CH
3
CH 2
CH
1
OUT PUT CHANNEL STA T US
Input
1
Input
2
Input
3
Input
4
Input
5
Input
6
Input
7
Input
8
Master
GAINLEVEL
MIN MAX
GATE P4 8 /
AT T.
GAINLEVEL
MIN MAX
GATE P4 8 /
AT T.
GAINLEVEL
MIN MAX
GATE P4 8 /
AT T.
GAINLEVEL
MIN MAX
GATE P4 8 /
AT T.
GAINLEVEL
MIN MAX
GATE P4 8 /
AT T.
GAINLEVEL
MIN MAX
GATE P4 8 /
AT T.
GAINLEVEL
MIN MAX
GATE P4 8 /
AT T.
front
back
Mic Level: 6600 ohms
Line Level: 8500 ohms
Balanced
Line Level: 300 ohms
Mic Level: 350 ohms
Unbalanced: 400 ohms
Direct Output: 60 ohms
–50 dBu (gain at Max)
22 dBm (THD+N at 1%)
50 mW (@ 1% THD+N) with 16 ohm load
69 dB
20 Hz to 20 kHz (±3 dB)
-130 dBu*
+48V DC
+4V DC
100/240V AC (auto-select), 50/60 Hz, 20W
32° to 104° F (0° to 40° C)
430.0 mm (16.93") W x 230.0 mm (9.05")
D x 44.0 mm (1.75") H (not including feet,
knobs and connectors)
3.8 kg (8 lbs. 6 oz)
483