Studio Technologies 72 Data Sheet

Model 72 Level Meter / Interface

The Model 72 Level Meter/Interface is a compact, portable device that plugs directly into an IFB or
intercom circuit and provides two useful functions: audio level meters and line-level audio outputs. IFB
(interrupt
talent cue audio. Intercom circuits are used by production personnel, supplying one or two channels
of “party-line” communications.

Two 5-segment LED meters allow direct observation of the audio signal levels present on the connected
IFB or intercom circuit. The display range is optimized for the signal levels found on typical “wet” (DC
with audio) IFB and intercom circuits, rather than traditional “VU” scaling.

Two audio outputs provide transformer-coupled “dry” signals, one output associated with each IFB or
intercom channel. These pro-audio-quality outputs are useful for a variety of production and testing
applications. For example, the outputs can serve as the interface between a traditional “wet” IFB system
and a wireless in-ear monitor or IFB system. The Model 72’s outputs can also be connected to line-level
inputs on an audio console, allowing IFB or intercom audio signals to be combined and/or routed to
other local or remote talent or production personnel cue systems. Other applications may arise where
an amplifi ed speaker needs to be used to monitor an IFB or intercom circuit. The Model 72’s audio
outputs will make achieving this fast and simple.

ible foldback) circuits are used in broadcast applications, providing one or two channels of

Power for the Model 72 is provided by the connected IFB or intercom circuit. Active circuitry ensures
accurate level metering and excellent audio performance. The compact device is housed in a rugged
aluminum enclosure. All inputs and outputs interface using industry-standard 3-pin male and female
XLR-type connectors. The connectors are manufactured by Neutrik® and feature gold-plated contacts
and metal housings.

View showing level meters and audio outputs

Highlights

• Compatible with virtually all IFB and intercom circuits

• Transformer-coupled line-level outputs

• Excellent audio quality

• 5-segment LED level meters

• Standard 3-pin XLR-type connectors

• Compact, portable unit

View showing IFB/intercom input and power present
LED indicator

The Model 72 is compatible with virtually all single- and dual-channel IFB and intercom circuits used in broad­cast, theatrical, and industrial applications. IFB circuits, typically provided by Studio Technologies’ IFB interface
units or the RTS™ 4000-series, can be directly connected. Industry-standard party-line intercom circuits are
also compatible. Whether a single-channel system from Clear-Com® or a dual-channel TW-series system from
RTS, direct connection to the Model 72 is supported.

The Model 72 provides both 3-pin male and female XLR-type connectors for direct interconnection with IFB and
intercom circuits. The connector’s pins are wired in parallel, allowing compatibility with interconnecting cables
having male or female connectors. The two connectors can also serve as a “loop through” function. Pin 1 of the
connectors is used as a common point for both DC power and audio signals. Pin 2 of the connectors is always
used for DC power, typically in the range of 25 to 30 volts. With dual-channel IFB or intercom circuits pin 2 is
also used to carry one of the two audio signals, typically designated as channel 1. (This audio signal is superim­posed onto the DC voltage.) Pin 3 is always used to carry an audio signal but never DC power. In dual-channel
IFB or intercom systems pin 3 typically carries channel 2 audio. In single-channel intercom systems pin 3 carries
the one and only audio signal.

The Model 72 was developed out of necessity, once again proving that the old saying is correct; necessity was
defi nitely the “mother” when it came to the unit’s invention. The genesis was very simple. Often when testing
audio equipment out “in the fi eld,” Studio Technologies personnel felt “blind” when interfacing with IFB and inter­com circuits. Typically it was diffi cult to obtain “clean” balanced line-level audio signals, and never possible with
a nominal level approaching +4 dBu. Worse yet, confi rming the signal levels of an IFB or intercom circuit was
virtually impossible. It often seemed that the signal levels were either too low or too “hot,” but there was no
simple way available to establish that fact. With the Model 72 these problems should disappear. Monitoring
of the audio levels is clear and accurate, and balanced line-level outputs are directly available. Using the
Model 72, the concept of an intercom “dry box” is taken to another level.

Specifi cations

General Audio:

Frequency Response: 20 Hz-20 kHZ, ±0.5 dB

Distortion (THD+N): 0.02%, measured at 1 kHz, –10 dBu in/

+4 dBu out

S/N Ratio: 93 dB, referenced to –10 dBu in/+4 dBu out

Connectors:

IFB/Intercom Input: 3-pin male and female XLR-type

Audio Outputs: 3-pin male XLR-type

IFB/Intercom Input:

Typ e: single- or dual-channel, unbalanced (pin 1 common;

pin 2 DC (or DC with audio); pin 3 audio)

Impedance: 20 k ohms, nominal

Level: –10 dBu, nominal

Compatibility: virtually all single- and dual-channel IFB and

intercom circuits

Studio Technologies, Inc.

Telephone [phone]
www.studio-tech.com

Audio Outputs:

Typ e: balanced, transformer-coupled with series capacitors and

isolation resistors

Impedance: 600 ohms, nominal

Nominal Level: +4 dBu, measured with –10 dBu IFB/intercom

input level

Maximum Level: +16 dBu into 2 k ohms

Gain: 14 dB, input-to-output

Power Requirement:

22-32 Vdc, 42 mA (provided by IFB/intercom input)

Dimensions (Overall):

4.2 inches wide (10.7 cm)

2.0 inches high (5.1 cm)

4.7 inches deep (11.9 cm)

Weight: 0.8 pounds (0.35 kg)

Specifi cations subject to change without notice.
© by Studio Technologies, Inc., June 2004.

50024-0604, Issue 1