Studio Technologies 240 - Manual (Page 11)

Model 240 User Guide Issue 1, August 2013
Studio Technologies, Inc. Page 11
Audio sources are connected to the line
inputs by way of 3-pin female XLR con-
nectors which are located on the unit’s
back panel. Prepare the mating connectors
(males) so that pin 2 is signal high (+),
pin 3 is low (–), 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 (+) and both
pins 1 and 3 to shield. If connecting an
unbalanced source in this manner results
in hum or noise, try connecting pin 2 to
high (+) and pin 3 to shield; leave pin 1
unterminated.
Intercom Interface
The Model 240’s intercom interface is
designed to directly connect with standard
single- and dual-channel party-line (PL)
intercom circuits. The one or two audio sig-
nals provided by the intercom circuit 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 chan-
nels. The Model 240 can also be config-
ured to send main output channel 3 and
channel 4 audio to the intercom channels.
In addition, the intercom circuit can pro-
vide the DC power required to operate the
Model 240’s circuitry.
An intercom circuit is connected to the
Model 240 by way of a 3-pin female XLR
connector which is located on the back
panel. The mating connector (male) should
be wired so that common is on pin 1, DC
with channel 1 audio is on pin 2, and chan-
nel 2 audio is on pin 3. With single-channel
intercom circuits common is on pin 1, DC
power is on pin 2, and audio is connected
to pin 3.
The Model 240’s intercom interface is
directly compatible with broadcast and
production party-line intercom circuits as-
sociated with systems from manufacturers
such as RTS and Clear-Com. Intercom cir-
cuits associated with other similar systems
should be equally compatible. RTS TW-
series systems are normally interfaced
using 3-pin XLR connectors. These con-
nectors are wired with common on pin 1,
DC power and channel 1 audio on pin 2,
and channel 2 audio on pin 3. Most Clear-
Com party-line systems are single-channel
with common on pin 1, DC power on pin 2,
and audio on pin 3.
The DC power supplied by the connected
intercom circuit is generally sufficient to
operate the Model 240’s circuitry. The ac-
ceptable input range is 24 to 32 volts, with
a required current of 150 milliamperes.
Note that the specified input voltage is
given when measured directly at the Model
240’s intercom input connector (with the
connector terminated on the Model 240)
and not at the source of the intercom
circuit’s power.
Multi-Unit Interconnection
Two Model 240 units can be interconnect-
ed so as to function together. Audio sig-
nals on multiple main output channels are
combined passively; there is no internal
digital or analog busing created. (This is
“old school” but works well!) Interconnect-
ing cables would be prepared so that the
pins on two 3-pin female XLR connectors
would be connected 1-to-1, 2-to-2, and
3-to-3 and the combination routed to the
input on the destination device. The Model
240’s main output circuitry is designed to
be passively combined so there is no risk
of damage by doing this. The audio level
on both units will drop approximately 6 dB
due to the passive combining.