Audio Technica AT-MX381 SmartMixer Installation And Operation Manual page 7

Preamp Outputs
Each microphone channel has an independent unbalanced preamp output that
is separate from the main mixer output. This is the Direct Output pin on the
block screw connector for each input. This is helpful when it is necessary to
record the output of each individual channel, whether or not it is the active
mixer output (as is required, for example, in some courtroom proceedings).
These outputs can be configured before or after the channel's gate (default is
before gate). (Refer to SmartMixer Software Channel Setting Section.)
External Logic Switching and Control Voltage
The AT-MX381 is provided with external logic switching and control voltage
connections for each of the input channels, allowing the unit to be interfaced
with a wide variety of control and monitoring systems. By creatively using the
external control connections, the flexibility of the AT-MX381 can be expanded
far beyond basic automatic mixing. The following logic functions are provided
for each input channel.
Force-on
When a contact closure is provided between the Ch * - Force On con-
nection and ground (* indicates the channel number), that input is
"forced on" and will override any priority settings (front panel or software).
Force-off
When a contact closure is provided between the Ch * - Force Off con-
nection and ground (* indicated the channel number), that input is
"forced off" overriding any priority settings (front panel or software).
Gate Status Voltage Out
When a microphone channel turns "on," as indicated by its Gate LED on
the front panel, the channel's associated Gate Status (control voltage
out) goes "high" (+4 VDC). This signal can be used to light indicator
LED's or drive logic circuitry to, switch speaker zones on and off, select
video cameras, etc.
NOTE: The control voltage should not be connected directly to an inductive
load such as a relay coil, as damage to the mixer may result.
External Logic Connections
Connections for the external logic and control voltage appear on the rear
panel 25-Pin D-sub connector. It is designed to mate with a standard 25-Pin
Male D-sub connector (not provided). For connector pin-out assignments refer
to Table #1 below.
Note: External contact closures override PC control.
Table #1 DB-25 Connector Pin-outs
NOTE: This connector is NOT a computer data port. Connecting a computer or
other data device directly to it may cause damage to the device or the
SmartMixer.
Using Force-on/Force-off
To activate force-on/force-off, install a clo-
sure between the appropriate pin and
Ground Reference on the External Control
connector on back of unit.
Note: Force-ON/OFF contact closures override PC control fuctions. Channels
forced ON or OFF using these control points will NOT be reflected in the PC
control system.
Using Control Voltage Out
When a microphone channel
turns "on," as indicated by a
Selected Channel LED on the
front panel, the channel's asso-
ciated Control Voltage Out goes
"high" (+4VDC). See chart pin
connection. This signal can be
used to light indicator lamps,
switch speakers zones on and
off, select video cameras, etc.
The control voltage should not
be connected directly to an
inductive load such as a relay coil, as damage to the mixer may result.
D D a a i i s s y y - - c c h h a a i i n n i i n n g g M M i i x x e e r r s s
When more than eight microphones are needed, it is possible to daisy chain
multiple AT-MX381 SmartMixers together through the Link In/Out connectors
on their back panels (Fig. 2). Each AT-MX381 is supplied with a Link Cable that
carries control bus, audio, and configuration data between mixers. When
linked, all microphones in a multi-mixer system can be controlled by one
microphone connected to any mixer. Up to 16 AT-MX381 SmartMixers may be
daisy chained for a total of 128 input channels. However, due to the link data
protocol (used for the SmartMixer Software computer control and external
RS232 control), AT-MX351 and/or AT-MX341a SmartMixers cannot be linked to
an AT-MX381.
When running the provided link cables from one unit to another, connect the
cable from the LINK IN jack on Mixer #1 to the LINK OUT jack on Mixer #2, the
cable from the the LINK IN jack on Mixer #2 to the LINK OUT jack on Mixer #3,
etc. DO NOT connect a link cable from the last AT-MX381 back to the Master.
When linked, Mixer #1 becomes the Master; its output contains audio from all
mixers in the chain (Slaves). Each subsequent mixer in the chain will output its
eight inputs along with the inputs of those after it. The combined output is
then taken from the first mixer (Master) in the chain. Because lockout informa-
tion is passed between mixers through Link In/Out, the last-microphone-on
condition is not violated.
Example using three AT-MX381 SmartMixers:
Mixer #1 is the Master and receives all audio. Mixer #2 (Slave 1) receives
audio from Mixer #2 and Mixer #3 (Slave 2). Mixer #3 receives audio only from
its eight inputs. (Refer to Figure 3 on page 71)
Since the link cables pass control data along with audio, each mixer in the
chain is assigned an address upon power up. To ensure proper address
assignment, always power up Slave AT-MX381 units before applying power to
the Master. Alternatively, a power distribution scheme that applies power to
all connected devices at the same time may be used (i.e. a switched plug
strip).
NOTE: When systems are connected with link cables, it is necessary for all
connected mixers to be powered on in order for the system to operate.
Note that one or more mixers can be switched to "Manual" mode without
affecting the automatic operation of any other mixers in the chain.
NOMA information is passed between AT-MX381 mixers through Link In/Out. If
one or more of the linked AT-MX381 units has NOMA switched off, its micro-
phones will not be included in the NOMA calculation. Refer to NOMA section
for more information.
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