Manual
Model 43D User Guide Issue 1, September 2015
Studio Technologies, Inc. Page 7
This may be more descriptive as the
function is actually a program source that
gets interrupted with talkback audio. The
“program” channel is typically a continu-
ous source of program audio. An alternate
term is “program-only.” The source of
interrupt audio is typically a producer or
director who provides real-time informa-
tion to the on-air talent.
In other applications, talent will use a
single-ear headset, “ear bud,” or in-ear
monitor, keeping the other ear accessible
to ambient audio. This is frequently done
in electronic news gathering (ENG) or
sports-broadcast applications where live
interviews take place. An audio source
with program-with-interrupt is provided;
no program audio source is utilized.
Powered IFB Outputs
The Model 43D provides two, 2-channel
powered analog IFB outputs that are
designed to directly support connection
of listen-only user devices such as the
Models 32A, 33A, or 34 from Studio
Technologies. Each powered IFB output
provides both DC and two channels of
unbalanced audio. Two 3-pin male XLR
connectors, located on the Model 43D’s
back panel, are used to interface with
the listen-only user devices. Following
broadcast-industry conventions, pin 1
is the common connection, pin 2 has
28 volts DC with channel 1 audio super-
imposed on it, and pin 3 has channel 2
audio. Each power source supplies a
maximum current of 120 milliamperes.
The power supply outputs are monitored
for over-current and short-circuit condi-
tions. Under firmware (embedded soft-
ware) control the outputs will automatically
cycle off and on to help prevent damage
to the circuitry and connected equipment.
Line-Level IFB Outputs
In addition to the two, 2-channel powered
IFB outputs, the Model 43D also provides
two channels of analog line-level IFB. The
audio sources for the line-level outputs is
the same as used for channels 1 and 2 of
powered IFB output 2. The line-level out-
puts are intended to allow interconnection
with externally-powered listen-only user
devices, inputs on wireless IFB systems,
or analog inputs on consoles or related
audio devices. The line-level IFB outputs
have a nominal level of –10 dBu and are
transformer- and capacitor-coupled, help-
ing to ensure successful interconnection
with virtually any line-level analog input.
Pro Audio Quality
The Model 43D’s audio circuitry was
designed in the spirit of professional
audio equipment rather than that found
in typical IFB or talent cueing gear. High-
performance components are used
throughout, providing low-distortion,
low-noise, and high headroom. The Model
43D’s powered IFB output sources offer a
unique level of performance; their ability
to deliver power while maintaining audio
quality is simply excellent.
Audio Meters and Status
LEDs
The Model 43D provides four 5-segment
LED meters. The meters, located on the
front panel, display the level of the audio
signals associated with the two, 2-channel
IFB outputs. At the time of installation and
setup the meters are invaluable in help-
ing to confirm correct operation. During
normal operation the meters offer direct
confirmation of the unit’s audio signal
levels, helping to ensure that optimal