Studio Technologies 41 2007 - Manual (Page 5)

Model 41 User Guide Issue 2, February 2007
Studio Technologies, Inc. Page 5
Introduction
The Model 41 is designed to create broad-
cast-standard IFB circuits from line-level
audio sources. The unit’s primary applica-
tion is to interface analog outputs associat-
ed with digital matrix intercom systems with
broadcast IFB user devices. The Model
41 provides four independent IFB circuits.
Each IFB circuit provides DC power and
two analog audio signals to support the
connected IFB user devices. The Model
41’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
over-current and short circuit conditions.
Installation of the Model 41 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-type connectors. The compact,
one-rack-space package is constructed
using heavy-gauge steel components. The
unit’s mains power input can range from
100 to 230 volts, 50/60 hertz. This “univer-
sal input” ensures correct operation virtu-
ally anywhere in the world.
Model 41 Back Panel
Model 41 Front Panel
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 fold-
back is an alternate way of describing a
cue or monitor function. Adding “interrupt-
ible” before it means that the cue source
can be temporarily replaced with an audio
signal originating from a producer, direc-
tor, or other production personnel. IFB
circuits are often used in the broadcast in-
dustry for talent cueing applications, both
in studio and field settings. Both “dry”
and “wet” IFB circuits can be deployed
and their characteristics are worth review-
ing. 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 essentially a standard
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 nominal level of the DC
power source is typically in the range of
30 to 32 volts. The audio is unbalanced
with a typical nominal level of –10 dBu.
The Model 41 implements wet IFB circuits.
As such, in this user guide the term IFB
will always represent this type of circuit.