Studio Technologies Model 46A Dual 2-Wire Analog Audio to 4-Wire Analog 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 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 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 performance 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 V, 50/60 Hz for operation.

General Audio

Frequency Response

• ±2 dB 100 Hz to 8 kHz

Distortion (THD+N)

• <0.5%, measured at 1 kHz, 4-wire input to 2-wire interface pin 2

Signal-to-Noise Ratio

• >55 dB, measured at 1 kHz, 4-wire input to
• 2-wire interface pin 2

Connectors

Inputs from 4-Wire

• 3-pin female XLR

Outputs to 4-Wire

• 3-pin male XLR

2-Wire Party-Line Intercom

• 3-pin male XLR

Remote Control

• 10-pin header, requires optional 10-pin ribbon connector assembly

AC Mains

• 3-blade, IEC 320 C14 (mates with IEC 320 C13)

2-Wire Party-Line Intercom Interfaces: 2

Type

• 2-channel party-line (PL), unbalanced (pin 1 common; pin 2 channel 1 audio or DC with channel 1 audio; pin 3 channel 2 audio)

Compatibility

• Single- and 2-channel intercom systems such as from RTS® and Clear-Com®

Impedance, External Power Mode

• >10 k ohms

Impedance, Internal Power Mode

• 200 ohms

Nominal Level

• –10 or –14 dBu, selectable

“Mic Kill” Signal

• square wave, 24 kHz, ±1%

Internal Power Source

• 30 volts DC nominal, 315 mA maximum

Hybrids: 4, 2 per interface

Topology

• 3-section analog circuitry compensates for resistive, inductive, and capacitive 2-wire party-line loads

Nulling Method

• automatic upon user initiation, processor implements digital control of analog circuitry; null settings stored in non-volatile memory

Nulling Line Impedance Range

• 120-350 ohms

Nulling Cable Length Range

• 0-3500 feet, typical

Trans-Hybrid Loss

• >40 dB, typical at 800 Hz

4-Wire Inputs: 4, 2 per interface

Type

• transformer-coupled, capacitor isolated

Impedance

• 13 k ohms

Nominal Level

• 0, +4, +6, or +8 dBu, selectable in tandem with nominal output level

Maximum Level

• +22 dBu

4-Wire Outputs: 4, 2 per interface

Type

• transformer-coupled, capacitor isolated

Impedance

• 50 ohms nominal

Nominal Level

• 0, +4, +6, or +8 dBu, selectable in tandem with nominal input level

Maximum Level

• +20 dBu into 2 k ohms

Meters: 8

Function

• displays level of 4-wire inputs and outputs

Type

• 5-segment LED, modified VU ballistics

Remote Control Inputs: 3

Type

• optically coupled

Input

• 3-32 volts DC; 2 mA minimum for operation, 20 mA maximum

Functions

• auto null interface 1, auto null interface 2, and “mic kill”

Power

AC Mains Requirement

• 100-240 volts (–15/+10%), 50/60 Hz, 34 watts maximum

Dimensions & Weight

Width

• 19.0 inches wide (48.3 cm)

Height

• 1.72 inches high (4.4 cm)

Depth

• 8.4 inches deep (21.3 cm)

Weight

• 4.6 pounds (2.1 kg)

Mounting

• one space (1U) in a standard 19-inch rack