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Highlights
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Compatible with virtually all IFB and intercom circuits
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Transformer-coupled line-level outputs
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Excellent audio quality
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5-segment LED level meters
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Standard 3-pin XLR-type connectors
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Compact, portable unit
Overview
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
(interruptible foldback) circuits are used in broadcast applications,
providing one or two channels of 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 amplified 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.
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.
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
Telex®/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 Telex/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 definitely the "mother" when it came to the unit's invention. The
genesis was very simple. Often when testing audio equipment out "in the
field," Studio Technologies personnel felt "blind" when interfacing with IFB and intercom circuits. Typically it was difficult to obtain
"clean"
balanced line-level audio signals, and never possible with a nominal
level approaching +4 dBu. Worse yet, confirming 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.
Model
72 Specifications
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:
Type: 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
Audio Outputs:
Type: 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)
Specifications
subject to change without notice.
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