Manual

Model 43D User Guide Issue 1, September 2015
Studio Technologies, Inc. Page 11
Model 43D’s power with no interruption in
operation. (Of course, normal operation
will cease if both PoE and Ethernet data
support are lost.)
Powered IFB Outputs
The Model 43D provides two, 2-channel
powered IFB outputs. The powered IFB
outputs are intended to directly support
listen-only beltpacks such as the tal-
ent amplifier units available from Studio
Technologies. The four channels of audio
associated with the IFB outputs are pro-
vided by the receiver (input) channels of
the Dante Audio-over-Ethernet data con-
nection. These audio sources will usually
be routed, using the Dante Controller
application, from the desired Dante trans-
mitter (output) sources to the Model 43D’s
receiver (input) channels.
The signals that are present on the pow-
ered IFB outputs’ 3-pin male XLR con-
nectors are typical for broadcast powered
“wet” IFB circuits. Pin 1 is common for
power and audio, pin 2 is nominal 28 volts
DC with channel 1 audio modulated on
it, and pin 3 is channel 2 audio. The nomi-
nal audio levels on the IFB channels are
–10 dBu. The maximum current draw
from pin 2 to pin 1 is nominal 120 milliam-
peres. The circuitry associated with pin 3
is protected from damage should pin 2
(28 volts DC) be accidentally connected to
it. Both pins 2 and 3 are protected should
an external powered IFB or party-line (PL)
intercom circuit be connected to pin 2
and/or pin 3.
One or more listen-only broadcast-
standard IFB devices can be connected
to each of the powered IFB outputs. The
only restriction on the number of units
that can be connected to each output is
that the total current drawn from each
output must be equal to or less than 120
milliamperes. Devices such as the Studio
Technologies’ Models 32A, 33A, or 34 are
directly compatible and will provide excel-
lent performance. While not cost-effective,
it’s also possible to use intercom belt-
packs such as the RTS® BP-325 as listen-
only devices.
The Models 32A and 33A each have a
quiescent current of approximately 15 mil-
liamperes and a maximum current draw
of 40 milliamperes. As such, a combina-
tion of up to three of these units can be
supported by each of the Model 43D’s
powered IFB outputs. With typical, rather
than maximum, audio signal levels being
sent to a powered IFB output supporting
four units is also possible. The Model 34
uses a maximum of 45 milliamperes so a
conservative application would have no
more than two Model 34 units connected
to each Model 43D powered IFB output.
Line-Level IFB Outputs
The Model 43D provides two line-level
IFB audio outputs. In the broadcast world
these might be referred to as “dry” IFB
outputs. The audio sources for these
outputs are the same as used by the two
channels associated with powered IFB
output 2. (These are the third and fourth
Dante audio channels that are routed, us-
ing Dante Controller, to the Model 43D’s
receiver inputs.) The IFB line outputs
are designed for general-purpose use
which could include connecting to exter-
nally-powered (typically battery-powered)
listen-only user beltpacks, transmitters
associated with wireless in-ear monitors,
audio consoles, or amplified speakers.
The outputs are analog, transformer-
coupled, capacitor-coupled, and will