Studio Technologies 230 2014 - Manual (Page 15)

Model 230 User Guide Issue 9, November 2014
Studio Technologies, Inc. Page 15
a device that receives the talkback signal,
such as an amplified loudspeaker, will
have an adjustable input sensitivity.
IFB Input
The Model 230’s IFB input is designed to
directly connect with “wet” (DC-biased)
IFB circuits. These circuits provide DC
power and one or two channels of audio
over a standard 3-conductor microphone-
style cable. Typically, the IFB circuit’s
interface connector is a 3-pin male XLR
wired so that common is on pin 1, DC with
channel 1 audio is on pin 2, and channel
2 audio is on pin 3. Some IFB circuits may
only have one audio channel. In this case,
audio will generally be on pin 3 with pin 2
providing only DC power.
The power supplied by an IFB circuit,
normally in the range of 28 to 32 volts DC,
is usually sufficient to operate the Model
230’s circuitry. The acceptable input range
is 24 to 32 volts, with a required current
of 125 milliamperes. Note that the speci-
fied input voltage is given when measured
directly at the Model 230’s IFB input con-
nector, not at the source of the IFB circuit.
The one or two audio signals provided by
the IFB circuit can serve as audio sources
for the headphone outputs.
While the Model 230’s IFB input was
designed for connection to a “wet” IFB
circuit, it’s also possible to connect line-
level audio sources. Please refer to the
Technical Notes section of this user guide
for details.
Line Inputs
The Model 230 allows two line-level
audio sources to be connected. These
sources can be individually routed to the
left-channel, right-channel, or both the
left- and right-channel headphone outputs.
The inputs are balanced, transformer-
coupled with a nominal impedance of
10 k ohms. Capacitors, in series with the
transformer’s input leads, prevent a DC
voltage present on a connected source
from impacting performance. The line in-
puts are compatible with signals that have
a nominal level of –12 dBV to +6 dBu. Two
trim potentiometers, located on the bot-
tom of the Model 230’s enclosure, allow
signals over this wide nominal level range
to be effectively utilized. Audio sources
are connected to the line inputs by way
of 3-pin female XLR connectors which are
located on the unit’s back panel.
Prepare the mating connectors (males) so
that pin 2 is signal high (+ or hot), pin 3 is
low (– or cold), and pin 1 is shield. If con-
necting a source in this manner results in
hum or noise, it’s possible that removing
the shield connection from pin 1 can elimi-
nate the issue. With an unbalanced source
connect pin 2 to signal high (+ or hot) and
both pins 1 and 3 to shield. If connect-
ing an unbalanced source in this manner
results in hum or noise, connect pin 2 to
high (+ or hot) and pin 3 to shield; leave
pin 1 unterminated.
Intercom Interface
The Model 230’s intercom interface is
designed to directly connect with standard
single- and dual-channel party-line inter-
com lines. The one or two audio signals
provided by the intercom line can serve as
audio sources for the headphone outputs.
Each signal can be individually assigned
to the left channel, the right channel, or
both the left and right channels. The Mod-
el 230 can be configured to send talkback
audio to either or both of the intercom
channels. In addition, the intercom line
can also provide the DC power required
to operate the Model 230’s circuitry.