Studio Technologies 230 2014 - Manual (Page 43)

Model 230 User Guide Issue 9, November 2014
Studio Technologies, Inc. Page 43
the Model 230’s nominal internal operating
level of –2 dBu. A 5:1 compression ratio is
implemented and, like the threshold level,
is not field adjustable. The threshold and
ratio settings were selected so that excel-
lent 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 whenever the com-
pressor’s threshold has been reached
and the circuit is actively controlling the
dynamic range. This LED is provided as
an aid when setting the gain of the micro-
phone preamplifier.
Auxiliary Relay
The Model 230 provides an auxiliary
relay for use in specialized applications.
Some “head scratching” or “brainstorm-
ing” should lead to a number of interest-
ing 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 switches.
Four operating modes are available: 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.
The relay provides two “form-C” contacts,
each consisting of a common, normally
open (not shorted), and normally closed
(shorted) connection. Obviously the two
form-C contacts change state in unison;
two independent relay functions are not
provided. These relay contacts are accessi-
ble on the Model 230’s main printed circuit
board assembly by way of two 3-position
header connectors. The contacts are titled
A and B, but there is no significance be-
tween the two. With both headers pin 1 is
normally closed, pin 2 is common, and pin
3 is normally open. For additional details
on connecting to the 3-position headers
please refer to the Additional Connectors
section in the Technical Notes area of this
user guide.
Main Output Source Selection
From the factory the Model 230 is config-
ured so that the output of the microphone
preamplifier is the audio source for the
main output. For most on-air applications
this is the desired source. It will provide
the most natural audio quality with the
potential for a large amount of dynamic
range. The output of the microphone pre-
amplifier is also connected to the input
of the compressor circuit. The output of
the compressor circuit supplies audio
to the talkback functions. Controlling the
dynamic range of the talkback audio
signals can minimize the chance of
cable crosstalk and equipment overload
in non-on-air signal chains.
But in the audio business exceptions
often turn out to be the rule. In some very
special applications it may be desirable
for the output of the compressor circuit to
be routed to the main output. This could
be especially true when the Model 230’s
system mode is selected for production
and the main output is serving as an addi-
tional talkback function. A “hidden” feature
allows the main output’s audio source to
be changed. From the factory, the output
of the microphone preamp is routed to the
main output by way of a 1 ohm resistor
“jumper” soldered into the Model 230’s
printed circuit board assembly. An alter-
nate component location is also included