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Model 45 User Guide Issue Preliminary 2, March 2009
Studio Technologies, Inc. Page 5
Introduction
The Model 45 is designed to interface
2-wire full-duplex party-line (PL) intercom
circuits with 4-wire audio circuits associ-
ated with matrix intercom systems. Appli-
cations for the Model 45 include television
sports and live-event broadcasting, theme
park and theater installations, corporate
AV, and industrial testing environments.
The unit provides one full-featured two-
channel 2-wire-to-4-wire interface. The
interface features hybrid circuitry that
includes automatic nulling capability. The
analog hybrids, under software control,
provide excellent audio quality and high
return-loss.
The Model 45 can be powered by an ex-
ternal source of 24 volts DC. The circuitry
is designed so that full isolation from the
connected party-line circuit is maintained.
Figure 2. Model 45 Back Panel
Figure 1. Model 45 Front Panel
The connected party-line intercom circuit
can also provide the Model 45’s operat-
ing power. For maximum flexibility the unit
is capable of supplying 30 volt DC power
and AC terminations, thus creating a
2-wire party-line intercom circuit. This
allows direct support for devices such
as intercom belt packs.
Configuration settings allow the Model
45’s performance to be optimized. Audio
level meters provide user confirmation
of system performance during setup and
operation. Standard audio connectors
are used for interfacing audio input, audio
output, party-line intercom, and DC power
signals. The Model 45 is housed in a com-
pact “half-rack” form factor that meets
the needs of broadcast “throw-down”
applications. Optional front panels allow
one or two Model 45 units to be mounted
in one space (“1U”) of a standard 19-inch
rack enclosure.