Studio Technologies 5121 User Manual
Model 5121
Line/IFB Output Module
User Guide
Issue 3, October 2014
This User Guide is applicable for serial numbers
M5121-00151 and later with firmware version 4.1 and higher
Copyright © 2014 by Studio Technologies, Inc., all rights reserved
www.studio-tech.com
50181-1014, Issue 3
This page intentionally left blank.
Model 5121
Line/IFB Output Module
Table of Contents
Introduction ................................................................... 5
Installation .................................................................... 7
Configuration ................................................................ 9
Operation ...................................................................... 9
Technical Notes ............................................................ 12
Specifications ............................................................... 16
Appendix A–Interconnection Details ............................. 17
Appendix B—Model 5121 Front Panel and
Printed Circuit Board (PCB) Dimensions ...................... 19
Model 5121 User Guide Issue 3, October 2014
Studio Technologies, Inc. Page 3
Model 5121
Line/IFB Output Module
This page intentionally left blank.
Issue 3, October 2014 Model 5121 User Guide
Page 4 Studio Technologies, Inc.
Model 5121
Line/IFB Output Module
Introduction
The Model 5121 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”
outputs and one powered “wet” IFB output,
in an easy-to-use 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 analog and digital audio
inputs, input level and status LED indicators, two analog line-level outputs, and a
2-channel powered “wet” broadcast-standard IFB output. Remote monitoring and
control capability is included to support
advanced applications. 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 5121 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 5121 modules used in
a project can vary widely—from one to dozens. In each case the Model 5121’s performance will be completely “pro” with audio
quality, reliability, and installation flexibility
matching that of larger-scale audio consoles, matrix intercom systems, and standalone IFB systems.
Typical applications will find either or both
of the Model 5121’s analog or digital audio
inputs being interfaced with outputs provided by fiber-optic transport modules, audio/
video routers, broadcast/production consoles, and matrix intercom systems. Only
one of the audio inputs, analog or digital,
will be used at any one time. No mixing
of the signals will take place. While both
physical inputs can be connected, by default the digital audio input will always take
precedence. In the automatic selection
mode the digital audio input will serve as
the Model 5121’s audio source should it be
present and “locked” to the input circuitry.
The analog audio input will be active whenever a digital audio signal is not present and
“locked.”
The Model 5121’s line-level outputs would
typically be connected to battery-powered
listen-only headphone amplifiers, ampli
fied speakers, or inputs on broadcast media storage systems. In remote-broadcast
Figure 1. Model 5121S Line/IFB Output Module Front and Back Views
Model 5121 User Guide Issue 3, October 2014
Studio Technologies, Inc. Page 5
Model 5121
Line/IFB Output Module
applications these two outputs may be
referred to as “dry” (no DC voltage present)
IFB signals. The Model 5121’s IFB output is
directly compatible with listen-only portable
IFB amplifiers, such as the Models 32A,
33A, or 34A from Studio Technologies, Inc.
The 2-channel IFB output provides signal
common on one pin, +28 volt DC power with
superimposed channel 1 audio on a second
pin, and channel 2 audio only on a third pin.
This complies with a long-popular broadcast-standard implementation.
Model 5121 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, “NEMA” I/O boxes, or
other specialized enclosures. It is expected
that integration firms will create applications
that use Model 5121 modules as part of
complete broadcast, production, corporate,
and government solutions. Sophisticated
users will be able to create “one-off” solutions to solve unique challenges.
Separate audio inputs are provided for interfacing with analog and digital audio sources.
The two analog inputs are balanced and
compatible with line-level signals. An unbalanced AES3 digital audio input allows the
connection of two audio channels. By default, input source selection is automatic. If
an AES3 digital audio source is connected
it will have priority. Two 7-segment LED
meters provide the user with an indication
of the input levels.
The Model 5121’s audio performance is
very good. Low-noise, wide dynamic-range
circuitry ensures that the input audio quality
is preserved. The audio source connected
by way of the digital audio input is routed to
a high-performance digital-to-analog converter (DAC) section that supports sample
rates of up to 48 kHz with a bit depth of up
to 24. The two audio signals coming from
the analog inputs or the DAC circuitry are
routed to two line-level analog audio output
sections. These provide the line-level, balanced, ESD-protected, capacitor-coupled
output signals.
The two signals coming from the active
audio input channels are also routed to
the IFB circuitry. One channel is used to
amplitude modulate the DC power source
circuitry. The second channel is routed to a
single-ended (unbalanced) line-driver circuit. The IFB 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 5121 monitors the DC output
voltage. Should a low-voltage/over-current
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
5121’s front panel, provides an indication
of the IFB output’s status. Note that for
additional flexibility, the source impedance of the IFB output channels is 200
ohms. This allows intercom user beltpacks
to serve as listen-only devices as well as
functioning as a small party-line intercom
system.
All audio inputs and outputs were carefully
designed for use in permanent as well as
field applications. Filtering on the analog
audio 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 over-voltage conditions
The DC power input is protected from accidental polarity reversal.
Issue 3, October 2014 Model 5121 User Guide
Page 6 Studio Technologies, Inc.
Loading...