Datasheet

ManualsBrandsSTUDIO TECHNOLOGIES ManualsAncillary Studio & Broadcast ProductsModel 46A - Dual 2-Wire Analogue Audio to 4-Wire Analogue Audio Interface

The Model 46A is designed to interface 2-wire full-duplex party-

line (PL) intercom circuits with 4-wire audio circuits associated

with matrix intercom systems. Other specialized audio system

interfacing applications can also be supported. The Model 46A

provides two independent full-featured 2-channel interfaces.

Each interface contains two hybrid circuits which include au

tomatic 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 party-line circuits. They are capable of supplying DC power,

allowing direct operation of devices such as user beltpacks.

Configuration settings allow the 2-wire and 4-wire interface

circuitry to be compatible with a range of nominal signal levels.

Audio level meters provide user confirmation of system perfor

mance during setup and operation. Applications for the Model

46A include television sports and special event broadcasting,

theme park and theater installations, corporate events, and

industrial testing environments. Standard audio connectors are

used for all input and output signals. The Model 46A mounts

in one space of a standard 19-inch rack enclosure and requires

100-240 volts, 50/60 Hz for operation.

2-Wire Interfaces

The Model 46A’s 2-wire interfaces are optimized for direct

connection with 2-channel party-line intercom circuits. In

• Two 2-channel party-line intercom interfaces

• Four analog hybrids with auto null capability

• Input and output level metering

• Excellent audio quality

• Integrated intercom power sources

• Standard audio connectors

• Transformer-coupled 4-wire inputs and outputs

• Universal input mains powered

Highlights

Dual 2-Wire Analog Audio to 4-Wire Analog Audio Interface

addition, single-channel party-line intercom circuits can also

be connected. Many broadcast applications use the 2-channel

TW-Series from RTS®, including 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 46A’s 2-wire inter

faces 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 virtu

ally all party-line systems. For example, for applications that

use equipment from RTS the –10 dBu setting is appropriate.

For other equipment, such as that from Clear-Com, the –14

setting is correct.

The Model 46A’s 2-wire interfaces can correctly function with

powered (“wet”) or unpowered (“dry”) intercom circuits. Pow

ered circuits have a DC voltage present, typically provided by

power supplies such as the RTS PS31 or Clear-Com PS-232.

This DC power, normally 30-32 volts, provides energy for con

nected devices such as user stations or beltpacks. In this type

of application the Model 46A is configured to operate in its

external 2-wire power source mode. In this mode the Model

46A’s circuitry maintains the required high-impedance load and,

as in all cases, draws no power from the party-line circuit. An

auto-terminate function ensures that should a “wet” circuit not

be connected, the Model 46A’s interface circuitry will remain

stable. This unique feature makes certain that objectionable

audio signals, including oscillations and “squeals,” will infre

quently be sent to the connected 4-wire device.

A significant capability of the Model 46A’s 2-wire interfaces is

their ability to supply DC power and 200 ohm AC termination

to the connected intercom circuits. Referred to as the Model

46A’s internal 2-wire power source mode, the 30 volt output

can power devices such as user stations and beltpacks. In many

applications this will eliminate the need for external intercom

50116-0914 Issue 1

Summary of content (4 pages)

PAGE 1
Dual 2-Wire Analog Audio to 4-Wire Analog Audio Interface Highlights addition, single-channel party-line intercom circuits can also be connected. Many broadcast applications use the 2-channel • Two 2-channel party-line intercom interfaces TW-Series from RTS®, including their popular BP325 beltpack.
PAGE 2
power supplies. Besides reducing total system cost, this feature 10 seconds for each channel of an interface. However, it’s can also lower system weight, reduce required mounting space, important to note that while the nulling process is automatic, it and decrease the mains energy requirement. only takes place upon user request.
PAGE 3
Pro Audio Quality press and release) of the auto null button will begin the auto null The Model 46A’s audio circuitry was designed in the spirit of process for channel 1. Two taps of the button will begin the auto professional audio equipment, rather than that found in typical null process for channel 2. For installer-selected applications, party-line intercom gear.
PAGE 4
potentiometers, fabricate special cabling and connector straps, that in many applications only a small number of user devices, use nulling earpieces, etc., had to be eliminated. For example, such as beltpacks, are typically connected to 2-wire party-line in virtually all instances, input and output levels fall within just a circuits.