Studio Technologies 42 - Manual (Page 7)

Issue 1, July 2004 Model 42 User Guide
Page 8 Studio Technologies, Inc.
dealer or distributor should provide an
AC mains cord for other destinations.
Locating the Model 42
The Model 42’s IFB circuits provide DC
power and unbalanced audio to operate
external IFB user devices. These devices
are often IFB “belt packs,” broadcast
announcer consoles, or other “talkback
boxes.” The Model 42’s mounting location
will dictate the length of the cable runs
needed to link the unit with the connected
devices. In some cases the location choice
is already established. For example, in
field broadcast applications the Model 42
will almost always be located in a produc-
tion truck or trailer. But in fixed applica-
tions it may be possible to select the
Model 42’s mounting location so as to
minimize cable length. In general, shorter
cables will lead to more reliable and
consistent system performance.
Mounting the Model 42
Once the desired mounting location has
been selected, the Model 42 will require
one space (1.75 vertical inches) in a stan-
dard 19-inch (48.3cm) equipment rack.
Secure the unit into the equipment rack
using two mounting screws per side.
Audio Input Connections
The Model 42 has eight line-level audio
inputs, arranged as four 2-channel pairs.
Each pair serves one of the four IFB cir-
cuits. Each IFB circuit, along with its two
associated audio inputs, is completely
independent. For on-air television applica-
tions the IFB sources are generally config-
ured to provide a single- or dual-channel
cue “feed” to talent personnel. In such
cases channel one of a pair is generally
designated as the “interrupt” channel
while channel two is the “program” chan-
nel. For other broadcast applications, such
as live radio, it’s possible that a stereo cue
source will be connected. In this situation
the left source would be connected to input
channel one while the right source would
be connected to input channel two. This
might also be the case with other profes-
sional audio applications, such as record-
ing and post-production.
Audio input connections are made by way
of one female 25-pin D-subminiature con-
nector which is located on the Model 42’s
back panel. A cable harness is required
with a 25-pin D-sub plug (male) on one
end and the desired mating connectors
on the other. This cable harness is not
supplied by Studio Technologies. (Note
that in some locations the term “cable
loom” may be used instead of “cable
harness.”) The wiring scheme used by
the D-sub complies with the now-ubiquitous
one made familiar by TASCAM® with their
DA-88® product. A wiring harness pre-
pared for connection to the Model 42’s
audio inputs is identical to a DA-88-style
input harness. Please refer to Figures 1 and
2 for connection details. Note that unlike
a DA-88-style harness, the Model 42’s
D-sub connector’s hold-down screws use
4-40 threads. This complies with the origi-
nal design standard for D-subminiature
connectors which used English rather
than metric thread pitch.
The Model 42’s audio input circuits have
a nominal signal level of +4dBu. They
are transformer coupled, have a nominal
impedance of 10K ohms, and compatible
with balanced or unbalanced sources.
Balanced sources should be wired so
that signal high is connected to the + pins,
signal low to the – pins, and shield to the
shield pins. With unbalanced sources,