Studio Technologies 42A 2008 - Manual (Page 7)

Model 42A User Guide Issue 2, February 2008
Studio Technologies, Inc. Page 7
Each Model 42A IFB circuit provides DC
power and two channels of unbalanced
audio by way of two 3-pin male XLR-type
connectors. The DC output is nominally
30 volts with a maximum rated current of
200 milliamperes. A major strength of the
Model 42A is the IFB circuit’s ability to
effectively deliver DC power over a vari-
ety of conditions. Unlike other interface
devices that use a common but less-than-
ideal circuit topology, a unique IFB circuit
was developed by Studio Technologies to
achieve the desired performance goals.
The result is a major improvement in
effectively supporting IFB user devices
over a wide range of conditions. Con-
nected devices can draw up to the full
rated 200 milliamperes of current with little
drop in DC voltage. This output voltage
stability is the key—whether 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 deployed 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
maintained. A headphone output is also
provided, allowing “real-world” checking
of IFB audio quality. In addition to being
able to manually select the IFB circuit to
be monitored by the meters and head-
phone output, an “auto scan” mode is
also included. This allows each of the four
IFB circuits to be monitored in a continu-
ously repeating sequence.
DC Monitoring and Fault
Shut Down
To prevent possible damage to the Model
42A’s IFB output circuitry, the DC output
voltage present on each IFB circuit is con-
tinually monitored. If the voltage on an IFB
circuit falls below 24 volts its associated
LED will “flash” as an error indication. If
this under-voltage condition continues for
more than 4 seconds a shut-down mode
will be entered, turning off power to the
IFB circuit. 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®, Drake,
Telex®/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 might be gained by config-
uring the nominal audio level of the inter-
com system’s “virtual” IFB output ports
to match the Model 42A’s +4 dBu input
level. With the Model 42A’s excellent audio
and power delivery performance it’s an
ideal alternative to the interface devices
offered by the intercom system vendors.
Using the Model 42A the intercom sys-
tem’s audio quality can be maintained
all the way to the IFB users.
The Model 42A’s IFB circuits allow virtually
every IFB user device to be supported.
These include the Model 30-series