Studio Technologies 5132 2012 - Manual (Page 12)

Issue 4, September 2012 Model 5132 User Guide
Page 12 Studio Technologies, Inc.
Model 5132
Party-Line Interface Module
nulling process are not excessively loud or
obnoxious, but most users might want to
remove their headsets during the process.
In addition to warning users it might be a
good time to ask them to mute any active
microphones. While the automatic “mic kill”
signal will apply to many user devices it
may not apply to all. Muting microphones
is important as obtaining a “deep” null
requires that no extraneous signals be
present on the party-line circuit.
Level Meters
The four audio level meters on the Model
5132 are calibrated differently from typi-
cal “VU” meter scales. Their “steps” are
labeled in reference to the level of the
signals being sent to, and received from,
the party-line interface. The ballistics of
the meters is also different, being a cross
between VU and peak.
During operation the green “0” LEDs will
light in response to audio levels of –10 dBu
being present on the party-line channels.
When a 5132S (SMPTE level) module has
its “0” LEDs lighting they correspond to
+4 dBu being present on its associated
4-wire audio input or output connections.
In the case of a 5132E (EBU level) module
the audio input and output level would be
0 dBu.
The four green LEDs of each meter in-
dicate that the levels are in the normal
range. The yellow LED lights when a signal
is approximately 6 or more dB above the
nominal (–10 dBu to or from the party-line
channel) level. Optimal signals will result in
the four green LEDs lighting almost solidly
with the yellow LED lighting only on peak
signals.
Internal Party-Line Power
Supply
If the Model 5132’s internal party-line inter-
com power source is enabled one or more
party-line user devices can be directly con-
nected and powered by the party-line in-
terface. The only restriction on the number
of user devices that can be connected is
that the total current draw must be equal to
or less than 180 milliamperes. Broadcast-
standard devices such as the RTS BP325
are directly compatible and will provide
excellent performance. Up to three of these
units can typically be supported.
For reference, this paragraph provides
details on the signals that are present on
the party-line intercom interface’s 3-pin
male XLR connector. When the internal
party-line power supply is active pin 1 pro-
vides common for power and audio; pin 2
has 28 volts DC with channel 1 audio;
pin 3 has channel 2 audio. The nominal
audio output level on the two channels
is –10 dBu, no matter if the module is a
5132S or a 5132E. The maximum current
draw from pin 2 to pin 1 is 180 milliam-
peres. The circuitry associated with
pin 3 is protected from damage should
pin 2 (nominal 28 volts DC) become
accidentally connected to it.
DC Voltage Monitoring
The pin 2 status LED can be a highly use-
ful “tool” for understanding the status of the
party-line intercom connection. It does this
by proving an indication of the DC voltage
that is present on pin 2 (with respect to
pin 1) of the Model 5132’s party-line inter-
face connector. The Model 5132’s micro-
controller integrated circuit, under software
control, “watches” to ensure that the DC