Manual

Issue 3, August 2018 Model 44D User Guide
Page 12 Studio Technologies, Inc.
As previously discussed in this guide, an
Ethernet connection that provides Power-
over-Ethernet (PoE) can serve as the Model
44D’s power source. Alternately, an exter-
nal 12 volt DC source can be connected.
For redundancy, both PoE and an external
12 volt DC source can be connected at
the same time. If both PoE and an external
12 volt DC source are connected, power
will be drawn only from the PoE supply. If
the PoE source becomes inoperative the
12 volt DC source will provide the Model
44D’s power with no interruption in op-
eration. (Of course, normal operation will
cease if both PoE and data transport fails
on the Ethernet connection.)
Line Inputs
The Model 44D provides two line inputs
that are intended for connection to line-lev-
el analog audio signal sources associated
with professional audio and video equip-
ment. It’s expected that the nominal level
of the analog sources will either be +4 dBu
for SMPTE applications or 0 dBu for EBU
applications. (Refer to the Configuration
section of this guide for details.) Common-
ly-used sources could include analog I/O
ports on broadcast matrix intercom sys-
tems, audio consoles, video storage and
playback systems, wireless microphone re-
ceivers, and audio testing equipment. The
circuitry associated with the line inputs is
analog, electronically balanced, capacitor
coupled, with an impedance of 20 k ohms.
Two 3-pin female XLR connectors, located
on the Model 44D’s back panel, are used
for interfacing with the source signals.
Prepare 3-pin male XLR mating connectors
such that pin 2 is signal high (+), pin 3 is
signal low (–), and pin 1 is common/shield.
It’s also highly possible that an unbal-
anced source will interface correctly. With
an unbalanced source begin by connecting
signal high (+) to pin 2 and signal low/
shield (–) to both pins 1 and 3. If this results
in hum or noise, next try connecting sig-
nal high (+) to pin 2 and signal low/shield
(–) only to pin 3; leave pin 1 unconnected
(“floating”).
If the Model 44D has been configured to
operate in the tone generator mode the
two analog line inputs will not be active.
As such, no connections should be made
to either line input channel 1 or line input
channel 2.
Line Outputs
The Model 44D provides two line outputs.
These analog outputs are designed for
general-purpose use which could include
connecting to analog inputs on devices
including matrix intercom systems, trans-
mitters associated with wireless in-ear
monitors, audio consoles, or amplified
speakers. The circuitry associated with the
line outputs is analog, capacitor-coupled,
and has a source impedance of 200 ohms.
It will perform optimally when driving loads
of 2 k (2000) ohms or greater. The nominal
level of the line outputs is configurable to
be either +4 dBu or 0 dBu, corresponding
to SMPTE or EBU applications. (Refer to
the Configuration section of this guide for
details.)
Two 3-pin male XLR connectors, located on
the Model 44D’s back panel, are provided
for interfacing the line outputs with associ-
ated equipment. Prepare 3-pin female XLR
mating connectors such that pin 3 is signal
high (+), pin 2 is signal low (–), and pin 1
is common/shield. To connect to an unbal-
anced load use pin 2 as signal high (+)
and pin 1 as low/shield; do not connect