Manual

Issue 3, August 2018 Model 44D User Guide
Page 14 Studio Technologies, Inc.
current of 400 milliamperes and a maxi-
mum of 60 volts DC or AC. They are not
intended for direct connection to AC mains
(high-voltage AC signals.).
Pins on a 9-pin female D-subminiature con-
nector (DE-9F), located on the Model 44D’s
back panel, allow interfacing with the GPO
connections. Two connections are provided
for each GPO, pins 1 and 6 for GPO 1 and
pins 2 and 7 for GPO 2. Refer to Figure 3
for connection details.
Auxiliary DC Output
A source of low-voltage, low-current DC
is available for support of special applica-
tions that use the GPO functions. The auxil-
iary DC output has a nominal voltage of
12 and is referenced to system common.
During normal operation the output can
range from 10 to 18 volts DC if an external
power source is connected to the Model
44D and is providing operating power.
Circuitry associated with the auxiliary DC
output limits the maximum current to 25
milliamperes. The auxiliary DC output is ac-
cessible by way of pin 5 of the 9-pin female
D-subminiature (DE-9F) connector that’s
located on the Model 44D’s back panel.
System common is provided on pins 8 and
9. Refer to figure 3 for connection details.
The exact use of the auxiliary DC output will
depend on the needs of the specific appli-
cations and the capabilities of the installer.
The auxiliary DC output can, for example,
be connected in series with a GPO’s relay
contact and used to directly light a status
LED, enable an optical coupler, or provide
a “GPO active” voltage output. Be careful
to limit the load placed on the auxiliary out-
put. Its circuitry will limit the current to 25
milliamperes but keeping it from reaching
that maximum value is a good idea.
Configuration
Back-Panel DIP Switches
A 4-position DIP switch assembly, labeled
Config, is located on the Model 44D’s
back panel. The switches are used to set
operating parameters, including line input
nominal level, line output nominal level,
low-pass filter on/off status, and operating
mode.
Line Input Nominal Level
Switch SW1 is used to configure the nomi-
nal level of the Model 44D’s two line input
channels. When SW1 is in its off (down)
position the line inputs are configured
such that connecting an analog signal
at a level of +4 dBu will result in a digital
signal at –20 dBFS being present on the
corresponding Dante output (transmitter)
channel. This would allow compatibility
with SMPTE standards. When SW1 is in its
up (on) position connecting an analog sig-
nal at a level of 0 dBu will result in a digital
signal at –18 dBFS being present on the
corresponding Dante output channel. This
is compliant with EBU standards.
The choices provided by SW1 are primar-
ily intended to allow the Model 44D’s line
input gain structure to be matched to the
needs of specific applications. Most North
American (SMPTE) applications will follow
+4 dBu in the analog domain being equal
Figure 4. Analog inputs nominal level
configuration switch