Studio Technologies 42A 2013 - Manual (Page 7)

Model 42A User Guide Issue 2, December 2013
Studio Technologies, Inc. Page 7
The Model 42A’s IFB outputs provide
power and two channels of unbalanced
audio over a single 3-conductor output.
The output power is 30 volts DC with a
maximum current of 220 milliamperes. A
major strength of the Model 42A is the IFB
output’s ability to effectively deliver DC
power over a variety of conditions. Unlike
other interface devices that use a com-
mon but less-than-ideal circuit topology, a
unique IFB output circuit was developed
by Studio Technologies to achieve the
desired performance goals. The result is a
major improvement in effectively support-
ing IFB user devices over a wide range of
conditions. Connected devices can draw
up to the maximum 220 milliamperes of
current with little drop in DC voltage. This
output voltage stability is the key—wheth-
er drawing 50, 100, or 200 milliamperes,
the output will remain close to 30 volts.
In practical terms this means that reliable
IFB-based cue systems can now be de-
ployed in more stadiums, concert halls, or
motor racing facilities than was previously
possible—longer cable runs, more user
devices, excellent performance.
Audio Monitoring
To help confirm proper installation and
ensure correct operation, the Model 42A
includes a full-featured audio monitor sec-
tion. Two 5-segment LED meters provide
an indication of the audio levels as they
appear directly on the IFB output connec-
tors. This capability makes it simple to
adjust and maintain correct audio levels
so that optimal IFB performance can be
achieved. A headphone output is also pro-
vided, allowing “real world” checking of
IFB audio quality. In addition to being able
to manually select the IFB output to be
monitored by the meters and headphone
output, an “auto scan” mode is also in-
cluded. This allows each of the four IFB
outputs to be monitored in a continuously
repeating sequence.
DC Monitoring and Fault
Shut Down
To prevent possible damage to the Model
42A’s output circuitry and connected user
devices, the DC output voltage present
on pin 2 of each IFB output is continually
monitored. If the voltage on an IFB output
falls below 24 volts its associated LED will
“flash” as an error indication. If this under-
voltage condition continues for more than
four seconds a shut down mode will be
entered, turning off power to the IFB out-
put. After a 10-second interval the output
will again become active.
Compatibility
The Model 42A is compatible with virtu-
ally every digital matrix intercom system,
including those from Clear-Com®, RTS®,
and Riedel®. Interfacing requires only the
connection of analog output ports from
the intercom system to the Model 42A’s
audio inputs. Optimal performance will be
gained by configuring the nominal audio
level of the intercom system’s “virtual” IFB
output ports to match the Model 42A’s
nominal +4 dBu input level. With the
Model 42A’s excellent audio and power
delivery performance it’s an ideal alterna-
tive to the interface devices offered by
the intercom system vendors. Using the
Model 42A the intercom system’s audio
quality can be maintained all the way to
the IFB users.
The Model 42A’s IFB outputs allow
virtually every type of IFB user device
to be supported. These include the