Studio Technologies 47A - Manual (Page 5)

Model 47A User Guide Issue 1, September 2014
Studio Technologies, Inc. Page 5
Introduction
The Model 47A is designed to interface
2-wire full-duplex party-line (PL) intercom
circuits with 4-wire audio circuits associ-
ated with matrix intercom systems. Other
specialized audio system interfacing ap-
plications can also be supported. The
Model 47A provides two independent full-
featured 2-channel interfaces. Each inter-
face contains two hybrid circuits which
include automatic nulling capability. The
analog circuitry, under software control,
provides excellent audio quality and high
return-loss. The interfaces are compatible
with powered and unpowered 2-wire par-
ty-line circuits. They are capable of sup-
plying DC power to devices such as user
beltpacks and user stations. Independent
power sources are provided for both chan-
nels (pins 2 and 3) of each interface, al-
lowing direct support for broadcast source
assignment panel (SAP) applications.
Configuration settings allow the 2-wire and
4-wire interface circuitry to be compat-
ible with a range of nominal signal levels.
Audio level meters provide user confirma-
tion of system performance during setup
and operation. Applications for the Model
47A include mobile and fixed television
facilities, theme park and theater installa-
tions, and industrial testing environments.
Model 47A Back Panel
Model 47A Front Panel
Standard audio connectors are used for all
input and output signals. The Model 47A
mounts in one space (1U) of a standard
19-inch rack enclosure and requires
100-240 volts, 50/60 Hz for operation.
2-Wire Interfaces
The Model 47A’s 2-wire interfaces are
optimized for direct connection with
2-channel party-line intercom circuits.
In addition, single-channel party-line inter-
com circuits can also be connected.
Many broadcast applications use the
2-channel TW-Series from RTS®, includ-
ing their popular BP325 beltpack. Other
industry-standard single- and 2-channel
PL intercom systems, including those from
Clear-Com®, are also directly compatible.
To provide optimal signal matching and
interface performance the nominal level of
the Model 47A’s 2-wire interfaces can be
selected. Using DIP switches, accessible
on the front panel, the nominal levels can
be selected to be either –10 or –14 dBu,
settings that should allow compatibility
with virtually all party-line systems.
The Model 47A’s 2-wire interfaces can
correctly function with powered (“wet”)
or unpowered (“dry”) intercom circuits.
Powered circuits have a DC voltage
present, typically provided by power