Studio Technologies 230 2008 - Manual (Page 47)

Model 230 User Guide Issue 7, October 2008
Studio Technologies, Inc. Page 47
Remote Control Connections
Provision has been made on the Model
230’s printed circuit board assembly to
allow external switches or contact clo-
sures to control the main out and talkback
button functions. Two 3-position headers
provide access to the circuitry associated
with the functions.
P15 (for rev C or D PCB):
P19 (for rev E or later PCB):
Pin 1 is connected to the common point
of the Model 230’s circuitry. Pin 2 is con-
nected to the circuitry associated with the
talkback 1 button. Pin 3 is connected to
the circuitry associated with the talkback 2
button.
P19 (for rev C or D PCB):
P18 (for rev E or later PCB):
Pin 1 is connected to the common point
of the Model 230’s circuitry. Pin 2 is con-
nected to the circuitry associated with the
main out pushbutton. Pin 3 is connected
to the circuitry associated with the auxil-
iary pushbutton input. (This function is
not currently supported in software.)
The input circuitry is “active low,” with a
10 k ohm resistor connected to +5 volts
acting as a pull up. A combination of resis-
tors and capacitors provide ESD protec-
tion. A qualified technician can use these
inputs for special applications. Contact
the factory for additional details.
Compressor Circuit
In this section some general information
about the Model 230’s compressor circuit
will be provided. As previously discussed,
the output of the microphone preampli-
fier circuit is connected to a studio-qual-
ity compressor circuit. The output of the
compressor is used by the talkback func-
tions and, if the unit has been modified,
the main output. (In most cases the main
output will utilize the signal coming direct-
ly out of the microphone preamplifier.) The
gain element in the compressor circuit is
a laser-trimmed voltage-controlled-ampli-
fier integrated circuit. It provides accurate,
low-noise, low-distortion performance. The
threshold of the compressor circuit is 2 dB
above the Model 230’s nominal internal
operating level of –2 dBu. A 5:1 compres-
sion ratio is implemented and, like the
threshold level, is not field adjustable. The
threshold and ratio settings were selected
so that excellent talkback audio would
be provided. By controlling the dynamic
range, intelligibility can be improved and
overloading of connected devices can be
avoided. An LED indicator lights when-
ever the compressor’s threshold has been
reached and the circuit is actively control-
ling the dynamic range. This LED is pro-
vided as an aid when setting the gain of
the microphone preamplifier.
Auxiliary Relay
The Model 230 provides an auxiliary relay
for use in specialized applications. Some
“head scratching” or “brainstorming”
should lead to a number of interesting
ways to take advantage of this unique
resource. To implement any auxiliary relay
application does require the services of a
qualified technician. This is because the
Model 230’s enclosure must be disas-
sembled and the desired wiring scheme
implemented. The relay operates under
software control, following the configura-
tion selected using two of the DIP-type
switches. Four operating modes are avail-
able: relay disabled, relay follows main
output status, relay follows talkback 1
status, and relay follows talkback 2 status.
These choices were previously discussed
in this user guide and should be reviewed.