Studio Technologies MODEL-45
2 Wire to 4 Wire Interface

MODEL-45

The Model 45 is designed to interface a 2-wire full-duplex party-line intercom circuit with a 4-wire audio circuit associated with a matrix intercom system. Other specialized audio system interfacing applications can also be supported. Applications for the Model 45 include television sports and special event broadcasting, theme park and theater installations, corporate events, and industrial testing environments.

The Model 45 provides a full-featured 2-channel interface which includes two hybrid circuits with automatic nulling capability. The analog hybrid circuitry provides excellent audio quality and high return-loss. For flexibility, the Model 45 can be powered by the connected 2-wire party-line circuit or by means of an external source of 24 volts DC. When powered by an external source the Model 45 is capable of supplying DC power to the 2-wire intercom circuit, allowing direct operation of devices such as user belt packs. Audio level meters provide confirmation of system performance during setup and operation. Standard audio connectors are used for all input and output signals. The Model 45's enclosure has a "1/2-rack" 1U form factor and weighs less than two pounds, making it well suited for use in portable applications. Alternately, using one of the optional rack-mount front panels, one or two Model 45 units can be mounted in a single space of a standard 19-inch rack enclosure.

The Model 45 uses standard 3-pin XLR-type connectors to allow convenient interconnection. For flexibility, both a male and female connector are provided for interfacing with the 2-wire party-line intercom circuit. The Model 45 is housed in a rugged yet lightweight aluminum enclosure that is designed to be "road tough." The Model 45 can be used as a standalone portable unit for "throw-down" applications. Two rack-mount options are also available allowing one or two units to be mounted in one space (1U) of a standard 19-inch rack enclosure.

Features:

• Portable "throw-down" or rack-mount use
• Analog hybrids with auto null capability
• Input and output level metering
• Excellent audio quality
• Flexible powering
• Standard audio connectors
• Transformer-coupled 4-wire inputs and outputs
• Integrated 2-wire intercom power source

Specifications:

General Audio:
Frequency Response: ±2.5 dB, 100 Hz to 8 kHz
Distortion (THD+N): <0.2%, 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

2-Wire Party-Line Intercom Interface:
Type: 2-channel party-line, unbalanced (pin 1 common; pin 2 DC with channel 1 audio; pin 3 channel 2 audio)
Compatibility: single- and dual-channel intercom systems such as from RTS® and Clear-Com®
Impedance–Normal: >10 k ohms
Impedance–2-Wire (PL) Power Source Mode: 200 ohms
Nominal Level: –10 dBu
"Mic Kill" Signal: square wave, 24 kHz, ±1%
2-Wire Power Source: 30 volts DC nominal, 300 milliamperes maximum

Hybrids: 2
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; settings stored in non-volatile memory
Nulling Line Impedance Range: 120 to 350 ohms
Nulling Cable Length Range: 0 to 3500 feet
Trans-Hybrid Loss: >40 dB, typical at 800 Hz

4-Wire Inputs: 2
Type: transformer-coupled, capacitor isolated
Impedance: 13 k ohms
Nominal Level: +4 dBu
Maximum Level: +22 dBu

4-Wire Outputs: 2
Type: transformer-coupled, capacitor isolated
Impedance: 50 ohms nominal
Nominal Level: +4 dBu
Maximum Level: +20 dBu into 2 k ohms

Meters: 4
Function: displays level of 4-wire inputs and outputs
Type: 5-segment LED, modified VU ballistics

Connectors:
4-Wire Line Inputs: 3-pin female XLR-type
4-Wire Line Outputs: 3-pin male XLR-type
2-Wire (PL) Interface: 3-pin male and female XLR-type
External 24 Volt DC Input: coaxial power jack, 2.1 x 5.5 mm, locking bushing, compatible with Switchcraft® S760K plug

Power Requirements:
External: 24 volts DC nominal, acceptable range 20 to 28, maximum required current 750 milliamperes @ 20 volts. Universal mains input/24 volt DC power supply shipped with each unit.
2-Wire Party-Line (when serving as source): 24 to 32 volts DC, 175 milliamperes

Dimensions – Portable "Throw-Down" Version (Overall):
8.7 inches wide (22.3 cm)
1.72 inches high (8.9 cm)
8.3 inches deep (21.3 cm)

Mounting Options: single-unit (M45RM-1) or dual-unit (M45RM-2) rack-mount front panels; each use one space (1U) in a standard 19-inch rack

Weight: 1.8 pounds (0.82 kg), rack-mount front panel adds 0.2 pounds (0.09 kg)

Our Part #  MODEL-45