Studio Technologies 5120 User Manual
Model 5120
Line/IFB Output Module
User Guide
Issue 3, November 2011
This User Guide is applicable for serial numbers
M5120-00151 and later
Copyright © 2011 by Studio Technologies, Inc., all rights reserved
www.studio-tech.com
50176-1111, Issue 3
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Model 5120
Line/IFB Output Module
Table of Contents
Introduction ................................................................... 5
Installation .................................................................... 7
Configuration ................................................................ 8
Operation ...................................................................... 9
Technical Notes ............................................................ 11
Specifications ............................................................... 16
Appendix A—Model 5120 Front Panel and
Printed Circuit Board (PCB) Dimensions ...................... 17
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Model 5120
Line/IFB Output Module
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Issue 3, November 2011 Model 5120 User Guide
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Model 5120
Line/IFB Output Module
Introduction
The Model 5120 Line/IFB Output Module is
a compact, self-contained 2-channel module intended for use in custom broadcast,
live-performance, and other specialized
audio applications. The module provides
broadcast and production talent cueing
interfaces, specifically two line-level (“dry”)
and one IFB (“wet”) outputs, in an easy-touse yet technically sophisticated package.
(Note that IFB is an acronym for Interrupted Fold Back, an arcane broadcast technical term meaning the cue signals sent
to on-air talent or other technical support
personnel.) The module’s basic functions
include selectable analog and digital audio
inputs, input level and status LED indicators, two analog line-level outputs, and a
2-channel DC-biased (“wet”) broadcaststandard IFB output. Module operation
requires only a source of analog or digital
audio, along with an externally-provided
source of 12 volts DC.
Applications for the Model 5120 include
sports broadcasting booth packages,
remote news gathering “fly-packs,” stadium
audio/video interface (I/O) locations, and
other broadcast-infrastructure projects.
The number of Model 5120 modules used
in a project can vary widely—from one to
dozens. In each case the Model 5120’s
performance will be completely “pro” with
audio quality, reliability, and installation
flexibility matching that of larger-scale
audio consoles, matrix intercom systems,
and stand-alone IFB systems. Typical
applications will find the Model 5120’s
analog and digital inputs being interfaced with outputs provided by fiber-optic
transport modules, audio/video routers,
broadcast/production consoles, and matrix
intercom systems.
The Model 5120’s line-level outputs would
typically be connected to battery-powered
listen-only headphone amplifiers, amplified
speakers, or inputs on broadcast media
storage systems. In remote-broadcast
applications these two outputs may be
referred to as “dry” (no DC voltage present)
IFB signals. The Model 5120’s IFB output
is directly compatible with listen-only por
table IFB amplifiers, such as the Models
32A, 33A, or 34A from Studio Technolo
gies, Inc. The 2-channel IFB output provides signal common on one pin, +28 volt
DC power with superimposed analog audio
on a second pin, and analog audio only on
a third pin. This complies with a long-popular broadcast-standard implementation.
Figure 1. Model 5120S Line/IFB Output Module front and back views
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Model 5120
Line/IFB Output Module
Model 5120 Line/IFB Output Modules do
not include a mounting enclosure or chassis. They are intended for mounting in
custom 19-inch rack panels, equipment
boxes, broadcast furniture, or other spe
cialized settings. It is expected that integration firms will create applications that use
Model 5120 modules as part of complete
broadcast, production, corporate, and
government solutions.
Separate audio inputs are provided for
interfacing with analog and digital audio
sources. The two analog inputs are balanced (differential) and compatible with
line-level signals. An unbalanced AES3id
digital audio input allows the connection
of two digital audio channels. A configuration DIP-type switch allows selection of the
desired input signal. Two 7-segment LED
meters provide the user with an indication
of the inputs levels.
The Model 5120’s audio performance is
very good. Low-noise, wide dynamic-range
circuitry ensures that the input audio quality is preserved. The audio from the digital
audio input is routed to a high-performance
digital-to-analog conversion (DAC) section
that supports sample rates of up to 48 kHz
with a bit depth of up to 24. The outputs
of the analog inputs or DAC circuitry are
routed to two line-level analog audio out
put sections. These provide the line-level,
balanced (differential), ESD-protected,
capacitor-coupled output signals.
The two analog signals from the selected
input channels are also routed to the IFB
circuitry. One channel is used to modulate
the DC power source circuitry. The second
channel is routed to a single-ended (unbalanced) line-driver circuit. The IFB power
source circuitry provides a low-noise,
current-limited source with a nominal
28 volt DC output. This is essentially identical to that created by “big time” broadcast
IFB systems. Logic circuitry contained
within the Model 5120 monitors the DC
output voltage. Should a low-voltage/overcurrent condition be detected the DC
output enters a protection mode. Once the
fault condition is removed normal operation will again resume. An LED, located on
the Model 5120’s front panel, provides an
indication of the IFB output’s status. Note
that for additional flexibility, the source
impedance of both IFB output channels is
200 ohms, allowing intercom “beltpacks” to
also serve as listen-only devices.
All audio inputs and outputs were carefully
designed for use in permanent as well as
field applications. Filtering on the inputs
minimizes the chance that radio frequency
(RF) energy will interfere with audio input
sources. Other components were included
to address ESD (“static”) and DC overvoltage conditions The DC power input is
protected from accidental polarity reversal.
The Model 5120 requires an external
source of nominal 12 volts DC for operation. The acceptable input voltage range
is 10 to 18 allowing a variety of power
sources to be utilized. Internal power sup
ply circuitry within the Model 5120 creates
the voltages required for the analog audio,
digital audio, and IFB circuitry.
Standard connectors are used throughout the Model 5120. Line-level and IFB
output connections are made using 3-pin
male XLR-type connectors. The two analog audio inputs use a 5-position, 0.1-inch
“header” connector. A DIN 1.0/2.3 coaxial
connector is used to interface with the digital audio input. The DC power input connections use a 4-position, 0.1-inch header.
Low-cost IDC (insulation displacement)
Issue 3, November 2011 Model 5120 User Guide
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