Studio Technologies 42A 2013 - Manual (Page 5)

Model 42A User Guide Issue 2, December 2013
Studio Technologies, Inc. Page 5
Introduction
The Model 42A is designed to create
broadcast-standard IFB outputs from line-
level audio sources. The unit’s primary
application is to interface analog outputs
associated with digital matrix intercom sys-
tems with broadcast IFB user devices. The
Model 42A creates four independent IFB
outputs. For convenience, the four outputs
can be connected by way of eight 3-pin
male XLR connectors; four of which are
located on the back panel and four on the
front. Each IFB output provides DC power
and two analog audio signals to support
the connected IFB user devices. The Model
42A’s audio quality is excellent; little hiss,
hum, or other artifacts are present. To
ensure optimal operation, the unit provides
resources for visually and audibly monitor-
ing the audio output signals. In addition,
the DC output voltage is monitored for fault
conditions.
Installation of the Model 42A is very simple.
Audio input connections are made using
a 25-pin D-subminiature connector. The
IFB output circuits interface using standard
3-pin XLR connectors. The compact, one-
rack-space package is constructed using
rugged steel and aluminum components.
Figure 1. Model 42A Interface front and back views
The unit’s AC mains power input can range
from 100 to 240 volts, 50/60 hertz. This
“universal input” ensures correct operation
virtually anywhere in the world.
There may be persons not familiar with the
term IFB. That’s not unreasonable as it’s a
somewhat obscure acronym for interrupt-
ible foldback. On its own, the term foldback
is an alternate way of describing a cue or
monitor function. Adding “interruptible”
before it means that the cue source can be
temporarily replaced with an audio signal
originating from a producer, director, or
other production personnel. IFB outputs
are often used in the broadcast industry
for talent cueing applications, both in
studio and field settings.
Both “dry” and “wet” IFB outputs can
be deployed and their characteristics
are worth reviewing. The term “dry” IFB
typically refers to a transformer-balanced
line-level audio circuit with a nominal level
in the range of 0 to +8 dBu. This is essen-
tially a standard analog audio circuit that
is commonly used to interconnect audio
equipment. The term “wet” IFB refers to a
circuit that combines DC power and one
or two channels of analog audio. The DC
power source is typically in the range of