for Surround Model 76DB Central Controller and Model 77B Control Console User Guide

for Surround Model 76DB Central Controller and Model 77B Control Console User Guide
for Surround
Model 76DB Central Controller and
Model 77B Control Console
User Guide
Issue 3, June 2009
This User Guide is applicable for systems consisting of:
Model 76DB: serial number M76DB-00151 and later with software version 2.02;
Model 77B: M77B-00151 and later with software version 2.00
© 2009 by Studio Technologies, Inc., all rights reserved
www.studio-tech.com
50232-0609, Issue 3
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for Surround
Table of Contents
Introduction ................................................................... 5
Installation .................................................................... 9
Configuration ................................................................17
Operation ......................................................................35
Technical Notes ............................................................43
Specifications ...............................................................48
Appendix A—Connection Pin-Out Charts ....................50
Appendix B—Sync Sources .........................................51
Model 76DB/77B User Guide
Studio Technologies, Inc.
Issue 3, June 2009
Page 3
for Surround
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Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
Introduction
What This User Guide Covers
This User Guide is designed to assist
you when installing and using the Model
76DB Central Controller and one or more
associated Model 77B or Model 71 Control
Consoles.
Overview
As creating and distributing multi-channel
surround (5.1) and stereo (2-channel) audio
material has become a day-to-day reality,
the ability to simply and effectively monitor
these sources is imperative for recording,
post-production, and broadcast facilities.
And with an “all-digital” world now upon
us, additional monitoring challenges have
arisen. Studio Technologies has addressed
these needs with the StudioComm for
Surround Model 76DB Central Controller
and the Model 77B and Model 71 Control
Consoles. With the digital audio inputs and
outputs, Dolby® E dialnorm support, and
extensive set of user resources it’s a simple
task to integrate a monitoring system into
virtually any facility. The carefully selected
group of features, including flexible input
source selection, multiple outputs, dialnorm
display, channel downmix, and multipleformat sync input, make the system powerful yet simple to operate. And by using the
best of contemporary technology, as well
as following rigorous design practices, the
system’s audio quality is excellent. Its unique
feature set makes it especially well suited to
meet the unique needs of broadcast master control applications.
An all-digital StudioComm for Surround
system starts with the Model 77B Control
Console. It’s the system’s “command center”
and is designed to reside at an operator’s
Model 76DB/77B User Guide
Studio Technologies, Inc.
location, allowing fingertip selection of
all monitoring functions. Numerous LED
indicators provide complete status information. A 4-digit numeric display indicates
the monitor output or dialnorm level in real
time. A major strength of the Model 77B is
its ability to configure, under software control, many important operating parameters.
The Model 71 Control Console is a compact user control surface that is intended
for secondary monitoring locations. It
provides three of the most basic functions:
a level control, dim, and reference level.
While many installations will use only one
Model 77B Control Console, up to a total
of four Model 77B or Model 71 Control
Consoles can be connected to a Model
76DB Central Controller. This provides
multiple users with full control over a facility’s monitor system. Making installation
simple, the Model 76DB provides power
for all connected Model 77B or Model 71
units.
The heart of this StudioComm system
is the Model 76DB Central Controller.
The one-rack-space unit contains all the
audio input, output, processing, and support circuitry. The Model 76DB provides
two surround (5.1) and three stereo audio
inputs. These unbalanced digital inputs are
AES3id/SMPTE 276M-compliant. Sources
of this type are ubiquitous in most postproduction and broadcast environments.
A sample rate of up to 192 kHz with a bit
depth of up to 24 are directly supported.
Circuitry associated with one of the stereo
inputs provides sample rate conversion
(SRC) capability, allowing a wide range
of digital audio source to be monitored.
Up to 340 milliseconds of input delay can
be selected to compensate for processing
delays in an associated video path. For
synchronization with a master timing
Issue 3, June 2009
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for Surround
reference the Model 76DB allows direct
connection of a word clock, DARS (AES11),
AES3id, bi-level video, and tri-level video
signal.
impedance is 110 ohms with a 5 volts peakto-peak (Vpp) level. For AES3id operation
the impedance is 75 ohms and the level is
1 Vpp.
Two surround (5.1) and two stereo monitor
outputs are provided. The post-fader surround monitor output is intended for connection to a monitor loudspeaker system.
The pre-fader surround monitor output
can be used with metering systems that
require signals that aren’t impacted by level
control or other monitoring functions. The
auxiliary stereo monitor output is provided
for special broadcast applications where
an independent output with separate on/off
control is desired. The stereo input C direct monitor output allows an installation to
directly access the SRC capabilities. For
installation flexibility the outputs can be
configured for compatibility with equipment
that requires AES3 (“balanced”) or AES3id
(“unbalanced”) digital audio signals. When
selected for AES3 compatibility the output
A source of Dolby E metadata can be
connected to the Model 76DB Central
Controller. This RS-485/RS-422 115.2 kbit/s
serial data signal carries numerous data
elements, including one that represents
the average dialog level of an associated
audio program. This dialog normalization
or “dialnorm” value is an integral part of
many broadcast distribution systems, ending up as part of consumer audio playback
systems. Hardware and software within
the Model 76DB separates the dialnorm
element that relates to one of the connected surround audio sources. This dialnorm
level value can be displayed on the Model
77B Control Console, as well as being used
to automatically adjust the post-fader surround monitor output level. This provides
a unique solution to the broadcast and
Figure 1. Model 76DB Central Controller Front Panel
Control console
status LED
Metadata
status
LED
Sync
status
LED
Figure 2. Model 76DB Central Controller Back Panel
AC mains
input connection
To/from
Models 77B &
71 Control
Consoles
RS-485 and
remote control
inputs
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Digital
monitor
output
connections
Sync
Input
connection
Surround Input B
connections
Stereo
Input C
connection
Stereo Input A and
Stereo Input B
connections
Surround Input A
connections
Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
Channel solo
Auxiliary monitor
output enable
Downmix
Display mode
Dialnorm and
monitor output
level display
Input select
Post-fader surround
monitor output
• Dialnorm enable
• Reference level
• Mute all
• Dim
• Rotary level control
Figure 3. Model 77B Control Console Front Panel
post-production world, allowing a professional environment to accurately simulate
an end user’s experience.
AC mains power is connected directly to
the Model 76DB, with an acceptable range
of 100 to 230 volts, 50/60 Hz.
Great care was taken in designing the
system’s architecture, ensuring that the
character of the audio input signals is
preserved. All audio processing is performed in 32 bits using a high-speed
field-programmable gate array (FPGA)
integrated circuit. A dynamic range of
greater than 123 dB is provided with less
than 1 dB of input-to-output noise added.
Additional Details
The Model 76DB occupies one space (1U)
in a standard 19-inch rack. Digital audio
signals are interfaced with the Model 76DB
using nine BNC connectors. Monitor output signal connections are made using
one 25-pin D-subminiature connector. One
9-pin D-subminiature connector is used to
connect the Model 76DB with up to four
Model 77B or Model 71 Control Consoles.
A second 9-pin “D-sub” connector is used
to interface Dolby E dialnorm data and remote control signals with the Model 76DB.
Model 76DB/77B User Guide
Studio Technologies, Inc.
The Model 77B provides four buttons and
associated LEDs for selecting the input
source to be monitored. The buttons are
designed such that up to six unique input
choices are available. Using the Model
77B’s configuration mode, each of the six
input choices can be configured from the
system’s two surround (5.1) and three
stereo inputs. The configuration mode also
allows stereo inputs A and B to be used as
either stereo or monaural sources. This is
especially useful in broadcast applications
where a 2-channel AES3id source may
carry two independent monaural signals.
To highlight this powerful feature: the
Model 77B allows independent monitoring of the two channels associated with a
single AES3id source. Broadcast master
control applications can greatly benefit
from this configuration flexibility.
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for Surround
The post-fader surround monitor output
level can be controlled by way of a large,
easy-to-use rotary control. The control,
actually a digital encoder, allows level
selection in precise 0.5-dB steps. The auto
mute all function causes the post-fader
surround monitor output channels to automatically mute whenever the output level
is set to its minimum position. Using the
reference level function, the post-fader surround monitor output level can be set to a
pre-configured value. This is provided for
audio-with-picture applications that require
a specific monitor output level. The reference level is easily configured by taking an
electronic “snapshot” of the desired monitor output level. For operator confirmation
a 4-digit LED readout can display the level
of the post-fader surround monitor output
channels. To match the needs of a facility,
it can be configured to display either the
attenuation level or the sound pressure
level (SPL).
The dim function allows the post-fader surround monitor output level to be reduced
by a fixed dB amount. The dim level is
configured from among four available
values. A mute all function allows all postfader surround monitor output channels
to be simultaneously muted. The channel
solo section provides individual post-fader
surround channel monitoring control,
allowing a single channel to be monitored
while the others are automatically muted.
Multiple channels can also be simultaneously selected for “soloing.”
A special solo mode is also provided,
called channel pop solo, which offers a
unique aid in monitoring audio material.
Channel pop solo allows the level of a
single channel to be raised while the level
of the other channel is reduced. This helps
to emphasize the content on one channel
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without fully muting the others. Broadcast
applications can benefit from the channel
pop solo mode allowing, for example, the
center channel to be highlighted while still
maintaining some level on the other channels. The amount of level increase—the
“pop”—as well as the amount of attenuation can be configured to meet the needs of
specific applications or users.
Two functions allow the input sources to
be checked for level or phase inconsistencies. The 5.1 to stereo downmix function
is used to create a stereo signal from the
selected surround (5.1) source. The stereo
to mono downmix function allows audio
on the left and right channels to be added
(summed) and monitored on the center
output channel. The two downmix functions
can be simultaneously enabled, allowing
a surround source to be checked for mono
compatibility. The downmix functions always
impact the post-fader surround monitor
outputs. A configuration setting allows the
pre-fader surround monitor outputs to be
selected for pre- or post-downmix operation.
In addition to the surround (5.1) monitor
output, a stereo auxiliary monitor output is
also provided. A stereo signal, connected to
stereo input C on the Model 76DB Central
Controller, can be routed to the auxiliary
output. A pushbutton on the Model 77B
Control Console allows on/off control of the
signal; no level control or signal modification
takes place. The auxiliary output feature can
be useful in special applications, e.g., in a
broadcast control room setting where an
audio signal, such as site-event cue signals,
needs to be monitored by way of an independent set of loudspeakers.
For flexibility, the StudioComm for Surround
system is designed to easily integrate with
equipment such as production intercom
Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
systems, on-air or recording tally signals,
or audio consoles. Three remote-control
input functions are provided: mute all, dim,
and auxiliary output on/off. By providing
access to these functions, talkback or slate
activity from an audio console or other
communications system can control the
level of the post-fader surround monitor
output or enable the auxiliary output.
Installation
In this section you will be installing the
Model 76DB Central Controller in an
equipment rack. Connections to the audio
inputs and monitor outputs will be made.
If desired, a source of Dolby E metadata
will be connected and external equipment
will be interfaced to the remote control
inputs. A location will be selected for the
first Model 77B Control Console and it
will be connected to the Model 76DB.
AC mains power will be connected to the
Model 76DB. For advanced applications up
to three additional Model 77B or Model 71
Control Console units can be connected to
the Model 76DB.
System Components
The main shipping carton contains one
each of the following: Model 76DB Central
Controller, Model 77B Control Console,
9-pin D-sub interconnecting cable, and
user guide. Also included in the shipping carton is a North American-standard
AC mains cord. Your dealer or distributor should provide an AC mains cord for
destinations outside of North America. Any
additional Model 77B or Model 71 Control Consoles will be shipped in separate
cartons.
Model 76DB/77B User Guide
Studio Technologies, Inc.
Mounting the Model 76DB
The Model 76DB Central Controller
requires one space in a standard 19-inch
(48.3 cm) equipment rack. Select a location
that is convenient for making connections
to the audio signals as well as interfacing
with the first (or only) Model 77B Control
Console. A cable is supplied to connect the
Model 76DB to the Model 77B. If the needs
of a specific installation dictate, an alternatelength interconnecting cable can be fabricated and used. Secure the Model 76DB
into the equipment rack using two mounting
screws per side.
Audio Connections
Audio connections are made by way of nine
BNC jacks and a 25-pin D-subminiature
connector. All the connectors are located
on the Model 76DB’s back panel. Refer
to Figure 2 for a detailed view of the back
panel.
Audio Inputs
Prior to digital audio sources being connected to the five inputs it’s worth reviewing how they are used by the StudioComm
system. Surround inputs A and B each have
six channels (5.1) and can be configured
for monitoring over the pre- and post-fader
surround monitor output channels. A oneto-one relationship is maintained between
the input channels and output channels, i.e.,
left input to left monitor output, right input to
right monitor output, center input to center
monitor output, etc. (Of course this won’t be
true in the case where the user has enabled
the 5.1 to stereo downmix function.)
Stereo inputs A and B can be configured to
be used as a stereo source or as two independent monaural sources. When configured as a stereo source the left channel is
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routed to the left monitor outputs and the
right channel to the right monitor outputs.
Alternately, the left and right input channels
can be independently configured to output
by way of the center channel of the surround
monitor outputs. In this way a single digital
audio source can supply one or two monaural signals to the StudioComm system and
be correctly monitored.
Stereo input C can serve as a source for the
pre- and post-fader surround monitor outputs. As with the other inputs, stereo input
C can be assigned, using the configuration
function, to an input select button. This will
allow stereo input C to be monitored using
the left and right channels of the surround
monitor outputs.
In addition, the signal connected to stereo
input C will be routed to the auxiliary monitor
output whenever that function is active. To
clarify: if the auxiliary monitor output is enabled a signal on the left channel of stereo
input C will be present on the left channel of
the auxiliary monitor output; a signal on the
right channel of stereo input C will be present on the auxiliary monitor output’s right
channel.
Stereo input C is also routed to the stereo
input C direct monitor output. A one-to-one
channel mapping scheme is maintained. The
signal present on the stereo input C direct
monitor output is post (after) the sample rate
conversion (SRC) and input delay functions
but pre (before) the downmix, level control,
and on/off functions.
It’s important to note that there is one limitation regarding stereo input C. Unlike stereo
inputs A and B, it can only be used as a
stereo (2-channel) source. Its left and right
channels can’t be independently monitored
over the center channel of the surround
monitor outputs. (The configuration function
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doesn’t allow this anyway so there is no
potential for a problem to develop.) Also,
the left and right channels of stereo input
C can’t be independently monitored by
way of the auxiliary monitor output. It follows a left-in-to-left-out, right-in-to-right-out
scheme.
The audio inputs support digital audio signals with sampling rates of up to 192 kHz
and a word length (depth) of up to 24 bits.
However, all the connected signal sources
must maintain a common sample rate
and timing reference. Having all signals
“locked” together ensures proper handling
by the Model 76DB’s all-digital signal path.
There is, however, an exception worth
noting. Circuitry associated with stereo
input C has sample rate conversion (SRC)
capability, allowing virtually any digital
audio signal to be connected. Refer to the
Technical Notes section of this guide for
a detailed review of the SRC capability.
A signal connected to stereo input C can
have an independent sample rate and
timing reference and still be monitored
correctly.
Nine BNC jacks (female) on the Model
76DB’s back panel are used to interface
with the 18 channels associated with the
digital audio signal sources; each BNC
connector carries two audio channels.
The digital audio inputs are intended for
connection to an unbalanced digital audio
source that is compatible with the AES3id
standard. In broadcast environments these
signals may also be referred to as following the SMPTE 276M standard. This signal
type has a nominal impedance of 75 ohms
with a nominal signal level of 1 Vpp. As expected, these digital audio sources should
be provided in the form of coaxial cables
with BNC plugs attached.
Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
Balanced AES3 digital audio signals
can also be used with the Model 76DB’s
inputs if external coupling transformers
(“baluns”) are utilized. These impedancematching (110 ohms to 75 ohms) and
level-attenuation transformer assemblies
typically provide a 3-pin female XLR connector on their input and a female BNC
connector on their output.
Monitor Outputs
The 25-pin D-subminiature connector
labeled Digital Monitor Outputs provides
access to the Model 76DB’s 16 channels of digital audio: pre-fader surround,
post-fader surround, auxiliary stereo, and
stereo input C direct monitor outputs. The
pre-fader surround monitor output channels are intended for connection to metering or monitoring equipment that requires
uninterrupted full-level signals. The postfader surround monitor output channels
are intended to connect to the main 5.1
loudspeaker system incorporated in a
facility. The auxiliary stereo monitor output is provided to support a separate set
of loudspeakers, the primary application
intended to allow monitoring of inter- or
intra-facility communications. The stereo
input C direct monitor output is essentially
a unity gain copy of the signal connected
to stereo input C. However, the signal does
pass through the sample rate conversion
(SRC) and input delay circuitry. The impact made by these functions will depend
on the specific input signal and the Model
76DB’s configuration settings.
It’s important to reiterate that all the monitor outputs are digital; the Model 76DB
doesn’t provide any analog outputs! This
requires that all equipment connected to
the Model 76DB’s monitor outputs provide
digital input capability.
Model 76DB/77B User Guide
Studio Technologies, Inc.
For flexibility the monitor outputs are transformer-coupled and can be configured to
act as AES3 or AES3id digital audio sources. The monitor outputs are configured as
groups with separate choices available
for the pre-fader surround/stereo input C
direct group and post-fader surround/
auxiliary monitor output group. When a
group is set for AES3 (110 ohms/5 Vpp)
the signals are compatible with AES3 interfaces. Signals of this type are normally interconnected using 3-pin XLR connectors.
When a group is configured for AES3id
(75 ohms/1 Vpp) the source impedance
and signal level are compatible with the
requirements of AES3id interfacing. These
signals are typically interconnected using BNC connectors. For details on how
a Model 77B is used to select the digital
monitor output types refer to the Configuration section of this user guide.
A cable assembly with a 25-pin D-sub plug
(male) on one end and the desired connectors on the other end will be used for
connecting to the digital monitor outputs.
The D-subminiature connector follows the
TASCAM® wiring convention, organizing
the 25 pins into eight groups of three pins
each; one pin remains unused. Each set of
three pins provides an independent interface. In the analog world this would allow
eight audio signals to be transported. But
with AES3/AES3id digital audio signals
this allows support for 16 audio channels;
eight interfaces each consisting of two
audio channels.
A wiring assembly prepared for the Model
76DB’s monitor outputs, when configured
for AES3 (110 ohms/5 Vpp), would be
identical to that of a DA-88-style output
assembly. An assembly of this type would
have a male 25-pin D-subminiature connector (DB-25M) on one end and eight
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3-pin male XLR connectors on the other.
A wiring assembly prepared for the Model
76DB’s digital monitor outputs, when set
for AES3id (75 ohms/1 Vpp), would
typically have eight BNC plugs attached.
For compatibility with AES3 balanced
digital audio signals connect the D-sub’s
+ terminal as signal high and the – terminal as signal low. In most applications a
3-pin XLR plug (male) will be used. In this
case the + signal would go to pin 2 of the
XLR, the – terminal to XLR pin 3, and the
shield terminal to XLR pin 1.
For compatibility with AES3id unbalanced
digital audio signals connect the D-sub’s
+ terminal as signal high, and both the
– and shield terminals as the signal low/
shield. When terminating to a BNC plug
the D-sub’s + terminal should connect to
the center pin; the – and the shield connections should go to the “body” of the
BNC plug. For optimal operation, it is best
to connect both – and shield together directly on the D-sub plug, rather than at the
BNC end of the interface assembly. Note
that the output circuitry is transformercoupled so it is possible to just connect to
the + and – terminals and still experience
correct operation. This would leave the
shield connection unterminated.
Refer to Figure 4 or Appendix A for the
exact connection details. Note that unlike
a DA-88-style assembly, the two threaded
fasteners associated with the Model
76DB’s D-sub connector use 4-40 threads.
This complies with the original design
standard for D-subminiature connectors.
Pre-Fader Surround Monitor Outputs
The pre-fader surround monitor output
channels are intended to connect to
metering, measurement, test, or other
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Connections
TASCAM® Signal
Channel High (+)
Signal
Low (–)
Shield
Pre-Fader L/R
1
24
12
25
Pre-Fader C/LFE
2
10
23
11
Pre-Fader LS/RS
3
21
9
22
Stereo Input C Direct
4
7
20
8
Post-Fader L/R
5
18
6
19
Post-Fader C/LFE
6
4
17
5
Post-Fader LS/RS
7
15
3
16
Auxiliary Stereo
8
1
14
2
Notes: 1) All signals transformer-coupled digital audio;
selectable for AES3 or AES3id compatibility.
2) Connector type on Model 76DB is 25-pin
D-subminiature female (DB-25F). Installer must
provide male (DB-25M). Connector uses 4-40
threaded inserts for locking with mating plug.
3) Wiring scheme follows TASCAM DA-88 convention.
Standard DA-88-type wiring harnesses are directly
compatible, with the exception of 4-40 screw threads
being required.
Figure 4. Connections for Monitor Outputs
signal monitoring equipment that require
uninterrupted, full-level digital audio signal
sources.
Post-Fader Surround Monitor Outputs
The post-fader surround monitor output
channels are designed for connection to
audio amplifiers associated with monitor loudspeakers or to the inputs of loudspeakers that contain integrated amplifiers.
Auxiliary Monitor Output
The auxiliary monitor output is intended
to connect to an amplifier associated with
a set of loudspeakers or an amplifiedspeaker. In either case a user level control
must be provided.
Stereo Input C Direct Monitor Output
The stereo input C direct monitor output
is intended for use in site-specific applications. It provides an uninterrupted, full-level
digital audio signal source.
Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
Sync Input
An external timing reference signal must be
connected to the Model 76DB. This synchronization (“sync”) signal must maintain
a stable relationship between itself and the
connected digital audio signals. The actual
sync source can be in one of several forms:
word clock, DARS, AES3id, bi-level video,
or tri-level video. The source of the Model
76DB’s sync reference will, in most cases,
be a dedicated sync signal connected to the
unit’s sync input. Alternately, the AES3idcompatible digital audio source connected
to the L/R input of surround A can also
serve as the sync reference. A configuration
choice, described later in this user guide,
is used to select the actual sync source to
be utilized. In this section of the user guide
details will be provided regarding connection of a dedicated sync signal to the sync
input. This is the recommended method and
in most cases should be utilized.
An overview of the various compatible
timing reference signals might prove worthwhile. Word clock is a digital signal that
is locked in phase and frequency to the
sample rate of the associated digital audio sources. DARS (digital audio reference
source) is a timing signal compliant with the
AES11 standard. It’s sometimes referred to
as “AES3-black.” Technically it is similar to
an AES3 or AES3id signal but is generated
specifically as a timing reference signal.
Bi-level video sync signals are typically
provided to support NTSC or PAL broadcast
applications, although they’re also used by
some later-generation equipment. Tri-level
sync signals are primarily associated with
facilities that support high-definition (HD)
video equipment. These tri-level signals can
be found at numerous rate combinations,
configured to allow for compatibility with the
various video formats. With all of these sync
Model 76DB/77B User Guide
Studio Technologies, Inc.
source choices available proper Model
76DB operation should be easy to obtain.
Extensive testing has been done using
many different sync source types and
rates. Interested users can refer to Appendix B of this user guide for details.
The external sync reference source should
be connected to the sync input BNC connector located on the Model 76DB’s back
panel. For flexibility the input can be configured to be high-impedance (“floating”) or
terminated with an impedance of 75 ohms.
A sync source that is dedicated for use by
the Model 76DB’s sync input will typically
have input termination enabled. If the sync
signal connected to the Model 76DB is being connected (“multed”) to other inputs it
may be desirable for the termination to be
disabled. A general “rule of thumb” is that
termination should be applied only at the
location of the last physical device using
a sync signal. Refer to the Configuration
section of this guide for details on how to
select the desired termination settings.
Metadata Input
The Model 76DB allows a source of
Dolby E metadata to be directly connected.
Hardware and software inside the Model
76DB extracts (“parses”) one of the dialnorm data elements from the connected
metadata signal. This dialnorm value can
be viewed on the Model 77B’s LED display
and, if desired, used to control the level
of the post-fader surround monitor output
channels. Refer to the Technical Notes
section of this guide for details.
The metadata signal is connected by
way of a 9-pin D-subminiature connector,
labeled RS-485/Remote Control Inputs,
which is located on the back panel of
the Model 76DB. Refer to Figure 5 or
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Signal
Pin
Direction
Data + (RS-485/RS-422)
7
Input
Data – (RS-485/RS-422)
2
Input
Data Shield
1
Shield
Remote Mute All
5
Input
Remote Dim
6
Input
Remote Aux Monitor Out On/Off
8
Input
Remote Spare
9
Input
Remote Common
4
Common
Note: Connector type on Model 76DB is 9-pin D-subminiature
female (DE-9F) Connector uses 4-40 threaded inserts
for locking with mating plug.
Figure 5. Connector Pin Outs for Metadata and
Remote Control Inputs
Appendix A for exact connection details.
While only the data + and data – connections are absolutely necessary, a shield
connection can also be made. Note that
the connections for the metadata signal
are reminiscent of the SMPTE 207M
standard.
The metadata signal must be in the form
of RS-485 or RS-422 asynchronous serial
data. This differential signal must have a
data rate of 115.2 kbit/s and a data format
of 8 data bits, no parity, and 1 stop bit
(8-N-1). A metadata signal of this type
is commonly available on metadatagenerating or de-embedding equipment
from broadcast equipment manufacturers
such as Dolby Laboratories®, Evertz®,
and NVISION®.
While in hardware the Model 76DB’s
RS-485 input connection is bi-directional,
in software it’s configured only to receive
data. The input impedance is 2200 ohms,
almost 20 times the nominal value for
RS-485. This means that there’s no reason
why a signal already connected between
two other pieces of equipment can’t also
be connected in parallel (“bridged”) with
the Model 76DB’s metadata input.
Issue 3, June 2009
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A word of advice—Studio Technologies
has found documentation supplied with
some metadata-generating equipment
has incorrect (or at least confusing) pinout information. This has resulted in much
head scratching and hair pulling. As such,
it may be valuable to use a logic analyzer
or oscilloscope to confirm that the metadata source is on the expected pins of the
source connector prior to connecting it to
the Model 76DB.
Remote Control Inputs
Support is provided for three remote
control input functions: remote mute all,
remote dim, and remote auxiliary monitor
output on/off. The inputs use logic gates,
“pulled up” to +5 volts DC by way of resistors, which are active whenever they are
brought to their logic low state. Inputs of
this type are commonly referred to as GPI
inputs. While the input circuitry is protected
from over-current and static (ESD) discharge, care should be taken to prevent
nasty signals from reaching them. The
inputs are active only when held in the low
state; they can’t be configured to change
state (“latch”) in response to a logic pulse.
The same 9-pin D-subminiature connector
used for the metadata input is also used
for the remote control inputs. Refer to
Figure 5 or Appendix A for the exact connection details. Note that pin 4 (remote
common) connects to the Model 76DB’s
internal circuit common connection as well
as the Model 76DB’s chassis and mains
earth connections. Figure 5 also shows
one spare remote control input (pin 9).
This is provided for future applications
and should remain unconnected.
Model 76DB/77B User Guide
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for Surround
Connecting the Model 76DB
to the Model 77B
A 9-pin female D-subminiature connector, labeled To/From Control Consoles, is
provided on the back panel of the Model
76DB Central Controller. This is used to
interface the unit with Model 77B Control
Consoles. A 9-pin female D-sub connector, labeled To/From Central Controller, is
provided on the back panel of each Model
77B Control Console. A cable with 9-pin
male D-sub connectors on each end is
used to interconnect the Model 76DB with
the Model 77B units. A cable is included in
the shipping carton. The cable implements
all nine connector pins in a one-to-one
manner.
Should an interconnecting cable of a
different length be required there’s no
problem for one to be fabricated and used.
While it can be wired in a one-to-one
fashion supporting all nine pins, only four
connections are required: pin 1 (data +),
pin 6 (data –), pin 4 (DC +), and pin 9
(DC –). The Model 76DB’s connector pinout scheme was designed to allow creation
of an interconnecting cable which uses
commonly available 2-pair audio cable.
This cable, consisting of two twisted pairs
each with an individual shield, is typically
sleek, flexible, and available in many colors. One pair and shield can be used for
the data connections while the other pair
and shield can be used for the DC connections. This implementation has the advantages of providing a shield for the data
path and a more robust common connection (two conductors including the shield)
for the DC power circuit. Refer to Figure 6
or Appendix A for details.
Model 76DB/77B User Guide
Studio Technologies, Inc.
Signal
Pin
Direction
Data + (RS-485)
1
To/From Models 77B/71
Data – (RS-485)
6
To/From Models 77B/71
Data Shield
2
To/From Models 77B/71
DC + (12 V)
4
To Models 77B/71
DC – (12 V Return)
9
To Models 77B/71
DC Power Shield
5
To/From Models 77B/71
Note: Connector type on Model 76DB is 9-pin D-subminiature
female (DE-9F). Connector uses 4-40 threaded inserts
for locking with mating plug.
Figure 6. Connections between Model 76DB and
Model 77B and Model 71
A few simple calculations are required to
determine the maximum cable length when
connecting a Model 77B to a Model 76DB.
The differential transmission scheme used
by the system’s RS-485 interface makes
an interconnection in excess of 1000 feet
(>300 meters) easily possible. The limiting
factor is typically the ability of the wiring to
pass the DC power supplied by the Model
76DB to the Model 77B. The Model 76DB
supplies 12 volt DC nominal with a maximum current of 500 milliamperes.
The Model 77B requires a minimum of
9 volts DC, 100 milliamperes maximum for
correct operation. (The voltage must be
measured directly at the Model 77B’s 9-pin
connector.) So the maximum interconnecting cable length is directly related to the
resistive voltage losses associated with the
two DC-carrying conductors. As the Model
76DB supplies 12 volts and the Model
77B requires 9 volts minimum, this directly
leads to a 3 volt DC maximum drop due
to the interconnecting cable. Using Ohm’s
law it’s quite easy to determine whether
the selected cable will support the desired
interconnection length. Calculate the voltage drop by multiplying the total resistance
(in ohms) of the proposed cable by 0.1 (the
Model 77B’s maximum required current).
Issue 3, June 2009
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for Surround
Remember to include the resistance in
both the DC + and DC – wires in the figure
for the total resistance. If it’s greater than
3 volts your cable is too long or the wire
gauge is too small.
Additional Control Consoles
Some installations may benefit from the
Model 76DB’s ability to be controlled by
additional control consoles. As expected,
at least one Model 77B Control Console
must be connected to a Model 76DB Central Controller. After this requirement has
been met up to three additional Model 77B
or Model 71 Control Consoles can also
be connected and powered by the Model
76DB.
When connecting multiple control consoles to a Model 76DB all nine pins of
each interconnecting cable can be connected in parallel (“multed”). This will
electrically mult the data and 12 volt DC
power signals between all the units. A custom cable implementation requires just four
pins to be connected: pin 1 (data +), pin 6
(data –), pin 4 (DC +), and pin 9 (DC –).
To make installation simple, a “bus” cable
assembly can be created using a short
length of ribbon cable with one male
and multiple female 9-pin D-subminiature
insulation-displacement connectors attached. Then standard 9-pin cables can
link the control consoles with the connectors on the bus cable.
Refer to the previous paragraphs of this
user guide where the issues involving
Model 76DB to Model 77B cable length
are discussed. Note the maximum required
current for a Model 77B is 100 milliamperes while a Model 71 requires only 35
milliamperes. It’s important to review this
Issue 3, June 2009
Page 16
information prior to creating the interconnection scheme to be used for installing
multiple Model 77B units.
AC Mains Power
The Model 76DB operates directly from
AC mains power of 100 to 230 V, 50/60 Hz.
Being a “universal input” device, there are
no switches to set or jumpers to install to
match a location’s mains voltage. The unit
uses a 3-pin IEC 320 C14-type inlet connector to mate with a detachable mains
cord. All units are supplied with a mains
cord that has a North-American standard
plug (NEMA 15L) on one end and an IEC
320 C13 socket on the other. Units bound
for other destinations require that the appropriate cord be used. The wire colors
in the mains cord must conform to the
internationally recognized color code and
should be terminated accordingly:
Connection
Neutral (N)
Line (L)
Protective Earth (E)
Wire Color
Light Blue
Brown
Green/Yellow
Safety Warning: The Model 76DB
does not contain an AC mains disconnect switch. As such, the AC mains
cord plug serves as the disconnection
device. Safety considerations require
that the plug and associated outlet be
easily accessible to allow rapid disconnection of AC mains power should it
prove necessary.
As soon as mains power is applied the
Model 76DB will perform a power-up sequence. The three LEDs on the right side
of the front panel will individually light in
a rapid right-to-left test sequence. Then
the three LEDs will flash in cadence while
Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
the firmware loads into the Model 76DB’s
main logic device. After just a few seconds
normal operation can commence and the
LEDs will perform their intended functions.
Once normal operating data is being interchanged with the one or more connected
Model 77B or Model 71 Control Consoles
the control console status LED will light. If
a source of metadata has been connected
and valid data is present the metadata status LED will light. The sync status LED will
light if a recognized sync source has been
connected.
Also upon application of mains power, all
connected Model 77B units will go through
a power-up sequence, lighting each of
its LEDs in succession. Using its 4-digit
display, each Model 77B will then momentarily display its address, its software
version, and the software versions of the
associated Model 76DB. At this point normal system operation can begin.
All connected Model 71 units will also go
through a power-up sequence after mains
power is applied to the Model 76DB. Each
of the units’ three status LEDs will light
momentarily. After the three status LEDs
have been lit, the device address will be
shown briefly using the dim and reference
level LEDs as shown in Figure 8. When
this is complete the Model 71 will enter the
normal operating mode and its status LED
will light if communications are established
with the Model 76DB. If the Model 71’s
status LED does not light check to see if
there is a device address conflict among
all connected control consoles and that all
cables are connected properly.
Should an error be detected during the
start-up process the three status LEDs
on the Model 76DB will continue to flash
in cadence indefinitely. On the Model 77B
Model 76DB/77B User Guide
Studio Technologies, Inc.
units a diagnostic code may be displayed.
Refer to the Technical Notes section of this
user guide for details.
Configuration
After the physical installation has been
completed it’s important that the system’s
configuration options be carefully reviewed.
In most cases one or more of the operating
parameters will need to be revised to meet
the needs of the specific installation. Many
of the configuration parameters will impact
the signal flow in to and out of the Model
76DB Central Controller. Other parameters
affect how the one or more Model 77B
Control Consoles will display status conditions and respond to user commands.
Most of the configuration choices will be
made using a Model 77B Control Console.
One configuration choice is available for
each of the connected Model 71 Control
Consoles.
Configurable Parameters
Many StudioComm functions can be configured to meet the exact needs of an installation. The Model 77B Control Console
is used to display and select the desired
system configuration. Here’s an overview
of what can be configured:
• Model 77B Device Address
• Stereo Input C Sample Rate Converter
• Auxiliary Monitor Output Nominal Level
• Sync Type
• Sync Input Termination
• Audio-Synced-to-Video Sample Rate
• Monitor Output Types
• Input Select Buttons
• Reference Level
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for Surround
• Overall Display Mode
• Reference Level in dB SPL
• Dialnorm Reference Level
• Dialnorm-Data-to-Surround-Input
Assignment
• Dim Level
• Remote Inputs
• Input Delay
• Channel Pop Solo Mode Offset Levels
• LFE Downmix Mode
• Pre-Fader Surround Monitor Output
Mode
Configuration diagrams, located later in
this section, give details on setting each
parameter. An overview of each configurable parameter is provided in the following
paragraphs.
Entering and Exiting the
Configuration Mode
A small button is located on the back of
each Model 77B Control Console, adjacent to the 9-pin D-sub connector. On any
connected Model 77B pressing and holding this button for two seconds places both
this specific unit and the Model 76DB into
their configuration modes. Other connected Model 77B and Model 71 units will
enter a standby mode. When the Model
76DB enters its configuration mode it will
immediately mute the monitor outputs as
a speaker protection measure. When a
Model 77B enters the configuration mode
its array of buttons and LEDs no longer
perform their normal functions, instead
they are used to display the operating
parameters and reflect configuration
changes as they are made.
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As a user aid, a Model 77B that has entered the configuration mode will have its
dialnorm and output level LEDs (associated with the display mode section) light
in an alternating manner. Other connected
Model 77B units will indicate that they have
entered the standby mode by simultaneously flashing their dialnorm and output
level LEDs.
To leave the configuration mode and return
the system to normal operation requires
one last action on the Model 77B unit that’s
in its configuration mode. Again press and
hold its configure button for two seconds.
Note that configuration changes are stored
in nonvolatile memory only after the configuration mode has been exited.
Our apologies to those of you who find
the configure button a pain to use, but it’s
supposed to be that way! Seriously, the top
of the button is slightly recessed from the
back panel, making it harder to accidentally activate. We didn’t want normal operation to cease because someone pushed a
Model 77B into a “rats nest” of schedules,
memos from management, and empty coffee cups! But a firm press with the fleshy
part of an index finger should do the trick.
There is no problem frequently “tweaking” the system’s operating parameters
to achieve the desired performance. The
configuration data is stored in nonvolatile
memory, which is rated for thousands of
read and write cycles and a retention time
in tens of years. Note that memory integrated circuits are located in the Model
76DB Central Controller as well as the
Model 77B and Model 71 Control Consoles. Only the individual device address
is stored in each Model 77B and Model
71. All other configuration parameters are
stored in the Model 76DB.
Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
Model 77B Device Address
A unique device address must be assigned
to each Model 77B that is connected to
a Model 76DB. The choices are A1, A2,
A3, or A4, with the default address being
A1. As most installations will find only one
Model 77B utilized, its default setting is appropriate. For installations that use a second, third, or fourth Model 77B each unit
must be configured with a unique device
address. Problems will occur if more than
one unit has the same address! It’s important to highlight the fact that the device
address is the only setting that must be
done on each individual Model 77B unit.
All other settings can be made on any one
of the connected Model 77B units. Be sure
that any selected address does not conflict
with addresses to be assigned to Model 71
units.
Stereo Input C Sample Rate
Converter
Circuitry associated with stereo input C
can provide sample rate conversion (SRC)
of connected digital audio signals. The
acceptable input range for sample rate
conversion is very wide, but is dependent
upon the output sample rate. With an output sample rate of 48 kHz any signal with
a sample rate over a range of 8 to 216 kHz
can be properly monitored by the system.
This capability can be especially useful
with signals that are not synchronized in
respect with the others connected to the
Model 76DB, even if the sample rate is
identical. The only compromise is that the
SRC process adds a fixed input-to-output
(group) delay of approximately 1 millisecond, a value that shouldn’t impact most installations. As such, it’s recommended that
the sample rate converter remain enabled.
However there might be special cases
Model 76DB/77B User Guide
Studio Technologies, Inc.
where this resource isn’t desired and it can
be disabled.
Auxiliary Monitor Output
Nominal Level
The nominal level of the stereo auxiliary
monitor output can be configured to match
the requirements of a specific installation.
Devices connected to the auxiliary monitor
output could include an amplifier associated with a loudspeaker system or inputs on
self-contained amplified loudspeakers.
(These types of devices must include a
means of adjusting their output level.) This
configuration setting defines the relative
output level when an input source is connected and the auxiliary monitor output is
enabled. The choices are 0, –6, –12, or
–18 dB. The 0 dB setting will typically be
correct when connecting to the input of a
device that’s not associated with a loudspeaker system. With no gain or loss, this
setting creates a unity-gain input-to-output
relationship. Devices such as amplified
speakers will often perform better when receiving signals with a lower nominal level.
In this case the ability to comfortably use
a level potentiometer may be enhanced by
selecting the –6, –12, or –18 dB settings.
Sync Type
The Model 76DB requires that the designated sync (external timing reference) signal be defined. Three of the choices—word
clock, DARS, and video—are associated
with a signal that is connected to the sync
input BNC connector. The fourth choice
allows an AES3id-compatible digital audio
signal connected to the L/R input of surround input A to serve as the sync source.
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Sync Input Termination
The sync input circuitry can be configured
to terminate the signal connected to the
back-panel sync input BNC connector. When
termination is selected a 75 ohm load is
applied to the signal. When the sync input
is not terminated the input impedance is
very high, essentially applying no load to
the source. If the sync source is connected
only to the Model 76DB then enabling termination is typically appropriate. If the sync
source is being “shared” by multiple inputs
then care must be taken so that the signal
is only terminated by one device.
Audio-Synced-to-Video Sample
Rate
If a video sync signal is being used as the
Model 76DB’s timing reference the sample
rate of the connected digital audio signals
must be specified. In most cases the default
value of 48 kHz will be appropriate, but rates
from 32 to 192 kHz are available.
Pre-Fader Surround/Stereo
Input C Direct Monitor Output
Type
To meet the needs of a specific installation
the nominal impedance and level characteristic of the pre-fader surround and stereo input C direct monitor outputs can be selected.
They are selected as a group; configuration
of individual outputs is not provided. If the
output signals are going to be connected to
balanced AES3 inputs then the setting that
provides a source impedance of 110 ohms
with a nominal 5 Vpp level would be appropriate. If the output signals are going to be
connected to unbalanced AES3id inputs
then the setting that provides a 75 ohm
source impedance and a nominal output
level of 1 Vpp would be correct.
Issue 3, June 2009
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Post-Fader Surround/
Auxiliary Monitor Output Type
The source impedance and output level of
the post-fader surround and auxiliary monitor outputs, as a group, can be configured.
The information previously provided concerning the pre-fader surround and stereo
input C direct monitor output type also
applies to these outputs.
Input Select Buttons
The three input select buttons, along with
the group select button, allow six source
configurations to be selected for monitoring. The Model 76DB has connections
for two surround (5.1) and three stereo
(2-channel) AES3id digital audio sources.
Any of these sources can be assigned to
any of the input select buttons. To fit broadcast applications where it’s typical for nonstereo pairs to share an AES3id 2-channel
path, the individual left and right audio
channels of stereo inputs A and B can be
assigned to separate input select buttons
as required. These “mono” signals will be
routed to the center pre- and post-fader
monitor output channels.
Spending time reviewing the input select
button configuration function may prove
very worthwhile. It is a unique feature of
this StudioComm for Surround system and
offers a great opportunity to optimize monitoring performance.
Reference Level
For audio-with-picture applications it’s
often beneficial for monitoring to be done
in reference to a known loudspeaker
level. This is often referred to as “mixing to
85 dB” on the monitors. The StudioComm
for Surround system allows a precise postfader surround monitor output level to be
Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
stored, and then enabled by pressing the
Model 77B button labeled Reference Level.
Setting the reference level is very simple
but care is required:
1. Set up a precision sound pressure
level (SPL) measuring device at the
desired listening location.
2. Place the StudioComm system in the
normal operating mode, not the configuration mode. Be certain that the
dim, mute all, reference level, dialnorm
enable, and downmix functions are not
active. The remote mute all and remote
dim functions must also not be active.
3. Use the Model 77B Control Console
to select the input source that contains
the desired reference signal source,
e.g., pink noise.
4. Observing the SPL meter, adjust the
Model 77B’s rotary level control until
the desired loudspeaker system reference level has been reached.
5. Being careful not to disturb the position of the rotary level control, enter the
configuration mode by pressing and
holding the configuration button located on the Model 77B’s back panel.
6. Once the configuration mode has been
entered, all the monitor outputs will
mute. Press and hold the reference level button; its associated LED will begin
to flash. After five seconds the LED will
light steadily to indicate that a “snapshot” of the new reference level has
been taken. The Model 77B’s numeric
display will then show the value of the
new reference level. The value shown
will always be a negative number as it’s
always a value less than the maximum
output level. The reference level button
can now be released.
Model 76DB/77B User Guide
Studio Technologies, Inc.
7. To complete the process the configuration mode must be exited. This is
performed by again pressing and holding the configure button for two seconds. The new reference level is now
stored in the Model 76DB’s nonvolatile
memory. Only by repeating the entire
procedure can the value be changed.
Once the configuration mode has been exited, the monitor outputs will again become
active. Confirm that the correct level has
been stored by pressing the reference level
button. The SPL meter should display the
desired level. If not, repeat the calibration
procedure to achieve the desired goal.
You might wonder why you have to press
and hold the reference level button for
five seconds before the selected value is
recognized. This is provided specifically so
that unauthorized users won’t accidentally
change the reference level while they experiment with the configuration mode. Only
if you know the “secret” will you be able to
store a new value.
Overall Display Mode
The Model 77B’s 4-digit numeric display
can be configured to display the post-fader
surround monitor output level in either an
attenuation mode or an SPL mode. In the
attenuation mode the output level is shown
as a reduction in level, in dB, relative to
the maximum output level. When the rotary
control is used to set the output level to
its maximum the display will show 0.0. As
the rotary control is moved in the counterclockwise direction the display will show
negative values, reaching –70.0 before the
full mute function automatically mutes the
outputs.
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for Surround
In the SPL mode the display can be configured to allow the output level to be
presented to users in terms of the actual
sound pressure level (SPL). Used in conjunction with the reference level in dB SPL
configuration and the stored reference
level, SPL mode allows a user to see a
visual representation of the SPL level that
is present in the listening environment.
While it takes a little more care to correctly
implement the SPL display mode, it can
offer an enhanced experience for StudioComm users.
Reference Level in dB SPL
The reference level in dB SPL configuration allows a specific SPL value to be
associated with the stored reference level
value. In this way whenever the monitor output is at the reference level, either
through activating the reference level function or manually adjusting the rotary level
control, the Model 77B’s display will show
the configured SPL level. Whenever the
monitor output is not at the reference value
the display will show the current value, in
dB, relative to the reference level. The reference level in dB SPL can be configured
over a range of 70.0 to 100.0 dB in 1.0-dB
steps. In many applications selecting a
value of 85 would be appropriate, reflecting the widely used audio-for-picture 85 dB
monitoring reference level. (Typically this
85 dB is really 85 dBC, indicating that a
C-weighting filter has been applied to the
measurement.) Other common reference
SPL values, such as 82 dB and 87 dB, are
well within the allowable range.
Dialnorm Reference Level
The dialnorm reference level parameter
is provided so that the StudioComm system can be configured to match a facilities’
Issue 3, June 2009
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or “plant” default dialnorm level. This value
is used as a reference against which the
post-fader surround monitor output level
will, if enabled, be adjusted up or down
in response to an incoming dialnorm value.
The dialnorm reference level parameter
can be adjusted over the entire –31 to
–1 dB range but typical values will be in
the range of –27 to –24. Implementation
purists might want to select –31 dB as it
may well be the “truest” implementation of
the dialnorm scheme. In this way the system will, when enabled, reduce the monitor
output level whenever dialnorm is different
than –31 dB. But as bar fights have broken
out over decisions such as this we’ll leave
the choice up to you! For additional information about dialnorm refer to the Technical Notes section of this user guide.
Dialnorm-Data-to-SurroundInput Assignment
For correct operation the connected Dolby
E dialnorm data must be assigned to work
in conjunction with its associated surround
input. In this way the dialnorm data will
only display, and level changes will only
take place, when the appropriate surround
input is selected by an operator.
Dim Level
The dim function is used to reduce the
post-fader surround monitor output level
by a preset amount. The reduction is in dB
relative to the post-fader surround monitor
output’s current level. There are four dim
level values available: –10.0, –15.0, –20.0,
and –25.0 dB.
Remote Mute All
Two configuration choices are associated
with the remote mute all function: disabled
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Studio Technologies, Inc.
for Surround
and enabled. To utilize the remote mute all
function simply requires you to select the
enabled setting.
Remote Dim
Two configuration choices are associated
with the remote dim function: disabled and
enabled. To utilize the remote dim function
simply configure it for enabled.
Remote Auxiliary Monitor
Output On/Off
This function configures whether the on/off
status of the auxiliary monitor output can
be controlled using the remote control
input.
Input Delay
A time delay can be added to the input
signals, allowing compensation for delays
that may be present on associated video
signals. The selected time delay applies
to all input signals and cannot be applied
selectively. The configured delay time is
referenced to a sample rate of 48 kHz.
In the case of input signals with a sample
rate of 48 kHz the delay range is 0 to 340
milliseconds. For other sample rates the
time must be linearly scaled. For example,
for a sample rate of 96 kHz the actual time
range is 0 to 170 milliseconds. In this case
selecting a delay of 120 on the Model 77B
will result in an actual time delay of 60 milliseconds. For 192 kHz sampling the time
range is 0 to 85 milliseconds. Selecting a
delay of 240 will result in a time delay of
60 milliseconds.
Channel Pop Solo Mode
Offset Levels
Two parameters can be configured that
set how the channel pop solo function will
Model 76DB/77B User Guide
Studio Technologies, Inc.
impact audio levels. The up offset level
sets the amount of increase (gain) that a
channel will experience when it is soloed
in the channel pop solo mode. The down
offset level sets the amount of decrease
(attenuation) that the non-soloed channels
will experience when a channel is active in
the channel pop solo mode.
LFE Downmix Mode
By default, when the 5.1 to stereo downmix function is active the LFE channel
associated with a surround input is muted.
This removes LFE content from the “downmixed” signal. In most applications this is
appropriate. However, for special situations
a configuration mode allows the LFE channel to be part of the downmix signal flow.
When the LFE downmix mode is enabled,
if surround input A or B is the active input
and the 5.1 to stereo downmix function is
active, the LFE signal level is reduced in
level by 6 dB and added to both the left
and right output channels. As expected,
even when the LFE downmix mode is active the LFE output channel will still mute
when 5.1 to stereo downmix is active.
Pre-Fader Surround Monitor
Output Mode
The pre-fader surround monitor output can
be configured as to its place in the Model
76DB’s signal flow. The choices are pre- or
post-downmix. In the pre-downmix mode
the output channels will not be impacted
by the state of the downmix functions.
This setting would be appropriate if the
pre-fader surround monitor outputs were
being routed to a storage system, routed
to another facility, etc. In this case the action of an operator enabling or disabling
the downmix functions won’t impact the
pre-fader surround monitor output signals.
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for Surround
If the post-downmix mode is selected the
pre-fader surround monitor outputs will
reflect the actions of the downmix functions. This choice would be correct if, for
example, level meters were connected to
the pre-fader surround monitor outputs. In
this scenario an operator would want to
visually observe the actions that the downmix functions impart on the signals.
Restore Factory Defaults
The restore factory defaults function is provided primarily for factory use. In this way
a system can be shipped with the default
settings selected. While you are welcome
to use this function, be careful so that
your configuration efforts aren’t wasted.
Specifically, be aware that the reference
level is reset to minimum level. All the other
parameters are fairly easy to set up, but
resetting the reference level would require
getting out an SPL meter and a calibrated
signal source. This is a hassle you may not
need!
Issue 3, June 2009
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Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
Configuration—Entering and Exiting Configuration Mode
and hold the configuration
 Press
button for 2 seconds to enter or
exit the configuration mode.
These LEDs will
light alternately
when configuration
mode is active.
Model 76DB/77B User Guide
Studio Technologies, Inc.
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Configuration—Model 77B Device Address, Stereo Input C
Sample Rate Converter, and Auxiliary Monitor Output Nominal
Level
and hold the Auxiliary Output
 Press
Enable button to display and select the
Model 77B’s device address, stereo
input C sample rate converter, and
auxiliary monitor output nominal level.
This LED displays the configuration of the stereo
input C sample rate converter (SRC). LED not
lit means SRC is bypassed; LED lit means SRC
enabled. Use the button to change the configuration.
Use the input buttons to select the nominal level
of the auxiliary monitor output.
LED Group 1-3 lit means the output level is 0 dB;
LED 1/4 lit means the output level is –6 dB;
LED 2/5 lit means the output level is –12 dB;
LED 3/6 lit means the output level is –18 dB.
Use the level control to change this specific
Model 77B’s device address. Address can
be either A1, A2, A3, or A4.
Default:
Device address A1.
Stereo input C sample rate converter enabled.
0 dB auxiliary monitor output nominal level.
Note:
The Model 77B’s device address is the only parameter stored in the Model 77B. All other parameters are
stored in the Model 76DB.
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Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
Configuration—Sync Type, Sync Input Termination, AudioSynced-to-Video Sample Rate, and Monitor Output Types
This LED displays the configuration of
the sync input termination. LED not lit
means sync input is not terminated; LED
lit means terminated with 75 ohms. Use
the button to change the configuration.
Use the Channel Solo C and LFE
buttons to select the pre-fader
surround/stereo input C direct
monitor output type. Use the
buttons to change the configuration. C LED lit means AES3id
(75 ohms/ 1 Vpp); LFE LED lit
means AES (110 ohms/5 Vpp).
Use the Channel Solo LS and
RS buttons to select the postfader surround/auxiliary monitor
output type. Use the buttons to
change the configuration. LS LED
lit means AES3id (75 ohms/
1 Vpp); RS LED lit means AES3
(110 ohms/5 Vpp).
Use the level control to adjust the
audio-syncedto-video sample
rate. Available
sample rates
are 32, 44.1, 48,
88.2, 96, 176.4,
and 192 kHz.
Use these buttons to select sync type.
LED Group 1-3 lit means video sync;
LED 1/4 lit means DARS;
LED 2/5 lit means word clock;
LED 3/6 lit means sync to surround input A L/R.
Default:
and hold the Mute All button to
 Press
display and select the sync type, sync
input termination, audio-synced-to-video
sample rate, and monitor output types.
Sync type video.
Sync input terminated.
Audio-synced-to-video sample rate 48 kHz.
Pre-fader surround/stereo input C direct monitor output type AES3 (110 ohms/5 Vpp).
Post-fader surround/auxiliary monitor output type AES3 (110 ohms/5 Vpp).
Model 76DB/77B User Guide
Studio Technologies, Inc.
Issue 3, June 2009
Page 27
for Surround
Configuration—Input Select Buttons
When an input button is pressed use the L
and R buttons to assign stereo input A to
that button. Both L and R LEDs lit means
stereo input A is assigned to that button
as a stereo source; L LED only lit means
channel 1 of stereo input A is routed to the
center output and channel 2 is not used;
R LED only lit means channel 2 of stereo
input A is routed to the center output and
channel 1 is not used.
When an input button is pressed use the C
and LFE buttons to assign stereo input B to
that button. Both C and LFE LEDs lit means
stereo input B is assigned to that button as a
stereo source; C LED only lit means channel
1 of stereo input B is routed to the center
output and channel 2 is not used; LFE LED
only lit means channel 2 of stereo input B is
routed to the center output and channel 1 is
not used.
When an input button is
pressed use the LS button
to assign stereo input C to
that button. Both LS and RS
LEDs lit means stereo input
C is assigned to that button
as a stereo source. Individual stereo input C channels
cannot be routed to center
output.
When an input
button is pressed
use the 5.1 to
Stereo button to
assign surround
input A to that
button. Use the
Stereo to Mono
button to assign
surround input B
to that button.

Press and hold an input button to display and select which input
source is assigned to that button in Group 1-3. Press and hold both
the group select button and an input button to display and select
which input is assigned to that button when Group 4-6 is active.
Default:
Surround input A assigned to input 1.
Surround input B assigned to input 2.
No input assigned to input 3 (disabled).
Stereo input A assigned to input 4.
Stereo input B assigned to input 5.
Stereo input C assigned to input 6.
Note:
If no input is assigned to an input button that button is disabled.
Issue 3, June 2009
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Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
Configuration—Reference Level
and hold the Reference Level button for 5 seconds to take a
 Press
“snapshot” of the level control’s setting at the time configuration mode
was entered. The Reference Level LED will flash when the button is
initially pressed and then light solid when the “snapshot” has been taken.
Default:
Reference level set for –60.0 dB post-fader monitor output level.
Note:
The 5-second delay is a safety feature ensuring that the reference level will not be accidently changed.
To permanently store the new value, you must still exit the configuration mode.
Model 76DB/77B User Guide
Studio Technologies, Inc.
Issue 3, June 2009
Page 29
for Surround
Configuration—Overall Display Mode and Reference Level
in dB SPL
Use the Channel Solo L and R buttons to select the
overall display mode. L LED lit means attenuation
mode is selected; R LED lit means SPL mode is
selected. Use the buttons to change the configuration.

Press and hold
the Display
Mode button
to display and
set the overall
display mode
and the reference level in
dB SPL.
Use the level control to adjust
the reference level in dB SPL.
The range is 70.0 to 100.0 dB
in 1.0-dB steps.
Default:
Attenuation display mode selected.
85.0 dB SPL reference level.
Issue 3, June 2009
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Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
Configuration—Dialnorm Reference Level and Dialnorm-Datato-Surround-Input Assignment
Use the Downmix 5.1 to Stereo and Stereo to Mono buttons to assign the
dialnorm data to the appropriate surround input. LED 5.1 to Stereo lit
means dialnorm data assigned to surround input A; LED Stereo to Mono lit
means dialnorm data assigned to surround input B.
and hold the Dialnorm
 Press
Enable button to display and set
the dialnorm reference level and
assign the dialnorm data.
Default:
Use the level control to adjust the
dialnorm reference level. The
range is –31 to –1 dB in 1-dB steps.
–31 dB dialnorm reference level.
Dialnorm data assigned to surround input A.
Model 76DB/77B User Guide
Studio Technologies, Inc.
Issue 3, June 2009
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Configuration—Dim Level, Remote Mute All, Remote Dim,
Remote Auxiliary Monitor Output On/Off, and Input Delay
This LED displays the configuration of remote mute all. LED not lit
means remote mute all is disabled;
LED lit means enabled. Use the
button to change the configuration.
This LED displays the configuration of remote dim. LED
not lit means remote dim
is disabled; LED lit means
enabled. Use the button to
change the configuration.
This LED displays the configuration of
remote auxiliary monitor output on/off.
LED not lit means remote auxiliary
monitor output on/off is disabled;
LED lit means enabled. Use the button to change the configuration.
Use the level
control to adjust
the input delay.
Range is from
0 to 340. The display shows delay
in milliseconds at
48 kHz sampling
rate. Scale up or
down for other
sample rates.
Use these buttons to select dim level.
LED Group 1-3 lit means –10 dB;
LED 1/4 lit means –15 dB;
LED 2/5 lit means –20 dB;
LED 3/6 lit means –25 dB.
Default:
and hold the Dim button to display
 Press
and select the dim level, remote mute
all, remote dim, remote auxiliary monitor
output on/off, and input delay.
–20 dB dim level.
Remote mute all enabled.
Remote dim enabled.
Remote auxiliary monitor output on/off enabled.
Input delay 0 ms.
Issue 3, June 2009
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Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
Configuration—Channel Pop Solo Mode Offset Levels, LFE
Downmix Mode, and Pre-Fader Surround Monitor Output Mode

Press and hold the
5.1 to Stereo button to display and
select the channel
pop solo up offset
level, to configure
LFE downmix, and
configure pre-fader
surround monitor
output mode.
When the 5.1 to Stereo button is pressed,
these LEDs display the configuration of the
pre-fader surround monitor output mode.
LED L lit means outputs are pre-downmix;
LED R lit means outputs are post-downmix.
Use the buttons to change the configuration.
When the 5.1 to Stereo button is pressed,
this LED displays the configuration of the
LFE downmix mode. LED not lit means
LFE downmix mode is disabled; LED lit
means enabled. Use the button to change
the configuration.

Press and hold the
Stereo to Mono
button to display
and select the
channel pop solo
down offset level.
When the 5.1 to Stereo button is pressed, use the level
control to adjust the channel pop solo up offset level.
The range is 0.0 to 12.0 in 0.5-dB steps.
When the Stereo to Mono button is pressed, use the level
control to adjust the channel pop solo down offset level.
The range is –0.0 to –12.0 in 0.5-dB steps and full mute.
Full mute is selected by adjusting the level control past
–12.0, at which point the display will show – – – –.
Default:
6.0 dB channel pop solo up offset level.
–6.0 dB channel pop solo down offset level.
LFE downmix disabled.
Pre-fader surround monitor output pre-downmix.
Model 76DB/77B User Guide
Studio Technologies, Inc.
Issue 3, June 2009
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Configuration—Restore Factory Defaults
and hold both the Dialnorm Enable and Dim buttons for 5 seconds
 Press
to restore Model 77B factory defaults. Once defaults have been restored,
the associated LEDs will light. After the buttons are released, configuration mode will be exited and normal operation will resume.
Factory Defaults:
Device address A1.
Stereo input C sample rate converter enabled.
0 dB auxiliary monitor output nominal level.
Sync type video.
Sync input terminated.
Audio-synced-to-video sample rate 48 kHz.
Pre-fader surround/stereo input C direct monitor output
type AES3 (110 ohms/5 Vpp).
Post-fader surround/auxiliary monitor output type
AES3 (110 ohms/5 Vpp).
Surround input A assigned to input 1.
Surround input B assigned to input 2.
No input assigned to input 3 (disabled).
Stereo input A assigned to input 4.
Stereo input B assigned to input 5.
Stereo input C assigned to input 6.
Reference level set for –60.0 dB post-fader monitor
output level.
Attenuation display mode selected.
85.0 dB SPL reference level.
–31 dB dialnorm reference level.
Dialnorm data assigned to surround input A.
–20 dB dim level.
Remote mute all enabled.
Remote dim enabled.
Remote auxiliary monitor output on/off enabled.
Input delay 0 ms.
6.0 dB channel pop solo up offset level.
–6.0 dB channel pop solo down offset level.
LFE downmix disabled.
Pre-fader surround monitor outputs pre-downmix.
Warning: Each Model 77B unit must have a unique address. Restoring factory defaults will reset only this specific
Model 77B to address A1. If another connected unit is already configured for address A1, normal system
operation will stop.
Note:
The 5-second button-press delay is a safety feature ensuring that the factory defaults will not be accidently
restored.
Issue 3, June 2009
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Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
Model 71 Control Console
Configuration
The only configuration choice available on
a Model 71 is its device address. It must be
selected so as not to conflict with the device
address of any other connected Model 71
or Model 77B Control Console. The choices
are A1, A2, A3, and A4. All Model 71 units
have a default device address of A4 while the
Model 77B’s have a default device address
of A1. This ensures that, in most cases, no
change will have to be made.
A small button is located on the back of each
Model 71 Control Console, adjacent to the
9-pin D-sub connector. On any connected
Model 71 pressing and holding this button
for two seconds places this specific unit in
its configuration mode; normal operation of
the Model 76DB and other connected Model
71 and Model 77B units will continue. When
a Model 71 enters its configuration mode its
three LEDs will no longer perform their usual
functions. Instead the status LED will blink
to indicate that configuration mode is active.
The dim and reference level LEDs will display the Model 71’s current device address.
The rotary level control is used to select the
desired device address; the LEDs will
respond accordingly. Refer to Figures 7 and
8 for details.
To leave the configuration mode and return
a Model 71 to normal operation requires one
last action; again press and hold its configure
button for two seconds. The selected device
address will be stored in a nonvolatile memory device that is located inside this specific
Model 71.
Model 76DB/77B User Guide
Studio Technologies, Inc.
Figure 7. Model 71 Control Console Front and
Back Panels
Address
Dim LED
Reference Level LED
A1
OFF
OFF
A2
OFF
ON
A3
ON
OFF
A4
ON
ON
Figure 8. Model 71 Device Address Chart
Operation
Now that you’ve installed and configured
the system, you’re ready to go. You should
find operation very easy. However, taking
time to study this section of the guide may
prove valuable, especially regarding the
system’s support for dialnorm.
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for Surround
Upon power up the system will return to
the last operating condition, including all
selected sources, downmix modes, etc.
As a precaution, however, the post-fader
monitor output level will always return to
its minimum value. The rotary level control
or the reference level button must then be
used to return the system to the desired
post-fader monitor output level.
Model 76DB Central
Controller
The Model 76DB’s front panel contains
three LEDs. The control console status
LED will light whenever the Model 76DB
is communicating under normal operation
with the one or more connected Model
77B or Model 71 units. A flashing control
console status LED indicates that the DC
power output supporting the control consoles is in a short-circuit or over-current
condition. The control console status LED
will not light when a Model 77B is in the
configuration mode or when the Model 77B
is going through its power-up sequence.
The metadata status LED will light whenever an active metadata signal has been
connected and valid metadata sync word
information is being received.
The sync status LED will light whenever
a valid timing reference signal is being
received by the Model 76DB. A flashing
sync status LED indicates that a valid sync
signal is not being received.
Control Consoles
StudioComm for Surround operation is
controlled using the up to four Model 77B
or Model 71 Control Consoles that have
been connected. System functions can
also be controlled by means of the metadata and remote control inputs.
Issue 3, June 2009
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Model 77B Control Console
To make things easy to describe, the
Model 77B’s operator functions are divided
into seven main groups: input source selection, downmix, monitor output general functions, channel solo, auxiliary monitor output,
display and display mode, and remote
control inputs.
Any change made to any one Model 77B
will be reflected in the status LEDs and
displays on all the connected units. Note
that all control console units function
simultaneously—there is no priority of
one unit over the others.
Input Source Selection
Four input select buttons work together to
allow pre- and post-fader monitoring of up
to six input source configurations. One button serves as a group select while the other
three select the specific input. The group
select button is used to select the active
group, alternating between groups 1-3 or
4-6. Two LEDs are associated with this button and indicate which group is active. The
other three buttons are used to select the
specific input source to be monitored. The
choices are 1/4, 2/5, and 3/6, with the active
input following the status of the group select
function. LEDs are associated with the input
select buttons and indicate which is active. Note that the Model 77B “remembers”
which specific input was last selected for
each group, so changing between groups
will switch between two specific inputs. This
allows rapid switching between, as an example, input 1 and input 6.
The specific sources assigned to the input
buttons depend on the signals connected
to the Model 76DB along with how the
system has been configured. Any input
Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
can be assigned to any input select button. (Technically, the same input could be
assigned to multiple buttons!) This means,
for example, that a surround input could
be monitored using any of the input select
buttons. The same holds true for a stereo,
dual channel, or monaural input source.
Downmix
Two downmix functions allow users to
perform “real-world” audio format compatibility checks. One function allows a
surround (5.1) signal to be “folded down”
(mixed) to stereo (2-channel). The other
allows a stereo signal to be converted to
mono. Using the downmix functions simply
requires pressing the desired button. The
buttons are set to always “latch” the functions on and off. An LED is located adjacent to each button and lights whenever its
respective function is active. The downmix
functions always impact the post-fader
surround monitor outputs. And, depending
on the selected configuration, they may
also impact the pre-fader surround monitor
outputs. Please refer to the Specifications
section of this guide for a detailed description on how the downmix functions perform
their tasks.
A specific downmix function can only be
enabled when it is applicable for the currently selected input source. This means
that the 5.1 to stereo downmix function
can only be enabled when a surround (5.1)
input source is selected. Neither of the
downmix functions can be enabled when
an input source configured for monaural is
selected. This is because an input of this
type is already monaural and wouldn’t be
impacted by any additional fold down.
The Model 77B associates the state of
the downmix functions with the currently
Model 76DB/77B User Guide
Studio Technologies, Inc.
selected input. For example, if input 2 is
the selected input source and the 5.1 to
stereo downmix function is enabled, this
condition will be “remembered” when
switching to a stereo or monaural input
source. Upon returning to input 2, the 5.1
to stereo downmix function will again
become active.
5.1 to Surround
When the 5.1 to stereo downmix function
is enabled the LS, RS, and C channels
associated with a surround signal are
combined (“folded down”) with the L and
R signals to create a 2-channel stereo
(left and right) signal. And, depending on
the system’s configuration, the LFE channel may also be combined with the L and
R signals. The resulting stereo signal,
sometimes known as LoRo, is routed
to the L and R surround monitor output
channels. The C, LFE, LS, and RS monitor
output channels are muted. By utilizing this
downmix function phase relationships and
inter-channel level issues can be quickly
observed.
Stereo to Mono
The stereo to monaural downmix function
combines the L and R audio channels to
create a single-channel monaural signal.
This signal is sent out the C monitor output
channel while the L, R, LS, RS, and LFE
monitor output channels are muted.
When a surround source has been selected for monitoring, the 5.1 to stereo
downmix function will automatically enable
whenever the stereo to mono downmix
function is enabled. This ensures that an
operator will hear a mono signal created
by folding down all channels associated
with the selected surround input.
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Monitor Output General
Functions
Four buttons and one rotary control are
associated with the post-fader surround
monitor output functions. The buttons control operation of the reference level, mute
all, dim, and dialnorm enable functions.
The rotary level control is used to manually
set the monitor output level. These buttons
and the rotary control do not impact the
pre-fader surround, auxiliary, and stereo
input C direct monitor outputs.
Reference Level
The reference level button sets the postfader surround monitor output level to a
preset value. Technical personnel, using
a sound-pressure-level (SPL) meter and
precision signal source, should have set
this level to meet the requirements of the
specific monitoring environment. The LED
associated with the reference level button
will light whenever the function is active.
Whenever the reference level mode is active the rotary level control is disabled. The
4-digit display will indicate the reference
output level. Note that the system’s default
reference level is –60.0 dB so “out of the
box” the Model 77B will display –60.0 when
reference level mode is enabled.
The reference level LED also serves as a
calibration aid. If the reference level mode
is not active, whenever the post-fader surround monitor output level is precisely the
same as that stored for the reference value
the reference level LED will flash. This
exact level can also be reached through
the use of the rotary level control, either
by itself or through the setting of the rotary
level control in conjunction with the dialnorm data and dim function. Whatever path
Issue 3, June 2009
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the output level takes to reach the reference level value, it will cause the reference
level LED to flash!
Mute All
Pressing the mute all button causes the
six channels associated with the post-fader
surround monitor output to mute. The
4-digit display indicates the mute condition by showing four dashes (– – – –). The
mute all button is always set to “latch” the
function on and off. The LED associated
with the mute all button will light whenever
mute all is active. Note that if mute all is
enabled via the remote mute all function,
the mute all LED will flash.
Dim
The dim function is provided for user convenience, allowing the post-fader surround
monitor output level to be reduced by a
fixed amount. The Model 77B’s configuration mode allows the dim level to be selected from among four choices: –10.0, –15.0,
–20.0, or –25.0 dB. Pressing the dim button will enable the function. The dim button
is always set to “latch” the function on and
off. The 4-digit display, when selected for
output level mode, will indicate the revised monitor output level. If the requested
“dimmed” output level is equal to or less
than –96.0 dB, the monitor output will go
into full mute and the display will show four
dashes (– – – –). When dim is active the
monitor output level reduction will apply no
matter whether the monitor output level is
being set by the rotary level control or by
the reference level button. The LED associated with the dim button will light whenever
dim is active. If dim mode is enabled via
the remote dim function the dim LED will
flash.
Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
It’s worth using a few sentences to discuss
the auto dim off function. Whenever dim
is enabled due to the dim button being
pressed, as well as the rotary level control
being active (reference level mode is not
active), changing the setting of the rotary
level control will automatically turn off
dim. The auto dim off function is a unique
attempt at protecting the aural health of
users. No longer will there be a heartstopping blast of audio when the dim button is pressed, supposedly to enable dim,
but actually turning dim off because it was
already enabled. It’s hard to explain unless
you’ve experienced this in person—trust
us, this situation can and does happen!
Note that the auto dim off function is not
active whenever dim is enabled due to
the remote dim function being active. This
allows remote control equipment, such
as a talkback system, to reliably dim the
monitor outputs.
Dialnorm Enable
Enabling the dialnorm level function simply requires pressing the dialnorm enable
button. The button provides a “latching”
function so that the selected state is maintained. An associated LED will light whenever the function is active. The dialnorm
enable function can only be activated when
the selected input source is a surround
signal that has been configured as having
dialnorm associated with it. (This is because dialnorm level data is available only
for that specific source.) When enabled, as
the dialnorm level changes the post-fader
surround monitor output level will automatically increase or decrease as appropriate. During configuration of the system a
dialnorm reference level was entered. This
level, typically in the range of –27 to –24
dB, is compared to the incoming dialnorm
Model 76DB/77B User Guide
Studio Technologies, Inc.
level value. If the current dialnorm level is
less than the reference value the output level
is increased by the difference. If the current
dialnorm level is greater than the reference
value the output level is decreased, again
by the difference. Note that dialnorm levels
are limited to a range of –31 to –1 dB. This
restricts the maximum amount of level control to 30 dB.
The 4-digit display, when selected for
output level display mode, will display all
level changes as they occur, including level
changes due to dialnorm activity. The current
dialnorm level value can itself be viewed by
selecting the display dialnorm mode.
In either display mode the decimal point
“dot” in the lower-right corner of the 4-digit
display will light whenever the current dialnorm value matches the dialnorm reference
value. This topic is described in greater detail
in the Display and Display Mode section later
on in this section. The Technical Notes section of this guide also will provide additional
useful information about dialnorm.
Rotary Level Control
The rotary level control is used to manually
adjust the post-fader surround monitor
output level. It is active whenever the reference level function is not active. The level
control provides the ability to adjust the
monitor output level over a 70 dB range.
Technically the rotary level control is a
24-step-per-revolution mechanical encoder.
The amount of level change in dB per step
(“click”) will depend on how quickly the control is turned. When changed slowly, each
step represents a 0.5 dB change in level. In
this case, to traverse the entire level range
would require rotating the control more than
four full turns. But the Model 77B’s software
detects when the control is rotated more
quickly and increases the amount of level
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for Surround
change in dB per step. A little experimentation will allow the user to acquire a good
“feel” for how best to use the control. The
reference level LED will flash when the
rotary level control sets the output level
to be the same as the stored reference
level. Whenever the rotary level control attempts to set the output level for less than
–70.0 dB, the post-fader surround monitor
output channels will automatically mute.
As previously discussed, the 4-digit display
indicates the mute condition by showing
four dashes (– – – –).
Channel Solo
The channel solo function allows specific
channels to be selected for individual
or group “solo” monitoring. The function
impacts the post-fader surround monitor
outputs, taking place electrically “after”
the input source selection, downmix, and
level control functions. Two solo modes
are available, normal and channel pop.
In the normal solo mode the level of a
channel selected for soloing actually
doesn’t change; the solo function causes
the non-soloed monitor output channels
to mute. In the channel pop solo mode the
level of the soloed channel will increase,
while the level of the non-soloed channels
will decrease. In this way the soloed channel will “pop out” from an audio mix so as
to be more easily observed. The actual
level changes that occur in pop solo are
dependent on how the system has been
configured.
Six buttons and associated LEDs, along
with the auxiliary monitor output enable
button, are associated with the channel
solo function. To solo a channel simply
requires pressing one of the solo buttons.
The buttons function in a press-to-enable/
press-to-disable “latching” mode. The LED
Issue 3, June 2009
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associated with a soloed channel is used
to indicate that solo is active.
The auxiliary monitor output enable button is used to select the solo mode. Using
this button the solo mode can be changed
any time between normal and channel pop.
Simply press and hold the auxiliary monitor output enable button for a few seconds
until all the channel solo LEDs light in the
desired manner; steady to indicate normal
solo mode and flashing for channel pop
solo mode. Once the state of the LEDs
change (steady-to-flashing or vice-versa)
the desired solo mode becomes active and
the button can be released. The selected
solo mode will be maintained even after
the system is powered down and subsequently powered up. In the normal solo
mode a soloed channel will have its associated LED light steadily. In the channel
pop solo mode a soloed channel will have
its associated LED flash.
For user flexibility, more than one output
channel can be selected for soloing at a
time. The Model 77B even allows all six
monitor output channels to be simultaneously selected for solo. This would seem
to be an “all soloed so none are soloed”
mode. But this condition is specifically
allowed so that when in the normal solo
mode an output channel mute function
can be provided. By first soloing all output
channels an operator can then “un-solo”
specific channels, directly muting them.
It’s a bit confusing to describe in words but
is very simple to use and can be a very
useful resource—try it out and you’ll see!
But note that while you can always solo all
channels, it’s really more useful to do this
when the system in configured for normal
solo mode. If selected for the channel pop
solo mode, soloing all the channels won’t
provide a very useful function.
Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
Auxiliary Monitor Output
As has been previously discussed in this
user guide, the auxiliary monitor output is
a stereo (2-channel) output signal that can
be used for special applications. The source
for this output is stereo input C. Using the
auxiliary monitor output enable button it can
be routed to the auxiliary monitor output as
desired. The button functions in an alternate
action manner to change the current state
of the output. An associated LED lights
whenever the auxiliary monitor output is
active. No level control, downmix, or other
Model 77B-supported functions will impact
the auxiliary monitor output.
Display and Display Mode
The Model 77B’s 4-digit LED display can be
selected to show either the level of the surround monitor output or the dialnorm level.
The display mode button is used to select
the desired mode. Two LEDs are associated
with this button, indicating which mode is
active. The button can also be used to display the Model 76DB’s current sample rate.
Both modes will indicate level in dB. What
the digits actually represent will depend on
how the Model 77B has been configured.
When selected for the output level display
mode, the post-fader surround monitor output level will be shown as either the amount
of attenuation or the sound pressure level
(SPL).
Display in dB Attenuation
If configured for the attenuation mode
the display will show the output level as an
attenuation value in reference to the maximum output. This is in the form of 0.5-dB
steps less than the maximum of 0.0 dB.
So a display of –40.5 would indicate that
the surround monitor output is set to be
Model 76DB/77B User Guide
Studio Technologies, Inc.
40.5 dB below the maximum level. As the
rotary level control is moved counterclockwise the output level will go down and the
indicated value will get more negative.
Display in dB SPL
If the Model 77B is configured to display
the post-fader surround monitor output level in dB SPL, the 4-digit display will always
show the output level in positive numbers.
These numbers are intended to represent
the sound pressure level in dB SPL, a
figure that should directly relate to the
actual sound pressure level that the loudspeaker system is presenting to users.
(Typically, the level value would actually
be in dBC, the C-weighted sound pressure
level.) When the reference level button is
enabled, or the rotary level control is set so
that the reference level has been reached,
the display will typically show something
in the range of 82 to 87 dB. Assuming
that the monitoring environment has been
correctly calibrated, this would indicate
that an average listening level of 85 dB,
for example, had been achieved.
Dialnorm Display
When the 4-digit display is set for the
dialnorm display mode a much different
piece of information will be shown to the
user. It will show the somewhat obscure
but important dialnorm level parameter
that’s associated with a surround input
source. As has been covered in other parts
of this user guide, dialnorm is intended to
provide a numeric value that represents
the average dialog level associated with
an audio-for-picture element. Technically,
dialnorm values can range from –31 to
–1 dB but during actual operation they will
typically be in the range of –30 to –20 dB.
The value may change relatively frequently
in conjunction with changes to the actual
Issue 3, June 2009
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for Surround
audio signal level. This would be the case,
for example, with a television program that
consists of alternating program and advertising segments. In other situations the dialnorm level will only change when an “on-air”
source is switched from typical stationoriginated segments to an extended-duration broadcast network program, such as
a live concert event. It’s also possible that
in some facilities the dialnorm level is fixed
and won’t ever change. That’s not really in
the spirit of what dialnorm is supposed to
accomplish, but c’est la vie. Whatever the
dialnorm level—the Model 77B will display it!
In both display modes a special feature is
provided to assist users in knowing if the
current dialnorm level matches a facility’s
“house” reference. This reference level,
typically in the range of –24 to –27 dB,
is entered as part of the Model 77B’s configuration process. The “dot” in the lower-right
corner of the 4-digit display will light whenever the current dialnorm level matches
the stored reference level. Refer to Figure
9. This feature can be useful in broadcast
transmission and distribution applications.
In theory, any time the dot in the lower-right
corner is not lit the current dialnorm level
value is causing a level adjustment to take
place. This level adjustment may be taking
place on the post-fader surround monitor
outputs if the dialnorm enable function is
active, as it would be for downstream users
of the broadcast signal.
Note that if a valid dialnorm source is not
available the 4-digit display, when selected
to display dialnorm, will show four dashes
(– – – –). This could be due to a problem
with the metadata signal connected to the
Model 76DB Central Controller. But more
frequently this will simply be the normal result that occurs when the Model 77B’s input
is not selected for the metadata-associated
surround input source.
Channel Pop Solo Display
As has been previously discussed, the
channel pop solo mode offers a unique
way of sonically highlighting an individual
channel. A channel selected for soloing
in this mode will have its level increased
while the other non-soloed channels will
be reduced in level. To highlight this condition, when the display mode is set for
output level the letters POP will appear in
the 4-digit display whenever a channel is
actively being “pop” soloed. This ensures
that a user will understand that the monitor
outputs no longer represent the true interchannel level relationships.
Display Current Sample Rate
Pressing and holding the display mode button will cause the current sample rate value
to be displayed: 32.0, 44.1, 48.0, 88.2, 96.0,
176.4, or 192.0. This can be useful during
troubleshooting or just for general interest.
Once the button is released normal display
operation will resume.
Figure 9. Incoming Dialnorm Level Match “Dot”
Issue 3, June 2009
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Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
Remote Control Inputs
As previously discussed in the Installation
section of this user guide, three remote
control signals can be connected to the
Model 76DB and then configured for
operation. The functions are remote mute
all, remote dim, and remote auxiliary
monitor output on/off. When an external
signal activates remote mute all the LED
on the Model 77B associated with the
mute all button will flash. If mute all was
already active when the remote mute all
function is activated, the LED will change
from being steadily lit to flashing.
When an external signal activates remote
dim the LED on the Model 77B associated
with the dim button will flash. If dim was already active when remote dim is activated,
the LED will change from being steadily lit
to flashing.
When an external signal activates the
remote auxiliary monitor output the LED
associated with the auxiliary monitor output enable button will flash. If the auxiliary
monitor output was already active when
remote auxiliary monitor output on/off is
activated, the LED will change from being
steadily lit to flashing.
Model 71 Control Console
The Model 71 Control Console provides
a limited number of pushbutton switches,
LEDs, and a rotary level control for operation status display and control. The
two buttons, along with associated LEDs,
provide access to the dim and reference
level functions. A rotary level control allows adjustment of the post-fader surround
monitor output level. A status LED lights
steadily whenever normal Model 71 operation is taking place.
Model 76DB/77B User Guide
Studio Technologies, Inc.
Any changes made using the Model 71’s
rotary level control and buttons will be
reflected in the appropriate status LEDs
and displays on connected Model 77B and
Model 71 units. And, as expected, changes
made using a Model 77B will be reflected
in the Model 71’s LEDs.
Rotary Level Control
The rotary level control is used to manually
adjust the post-fader surround monitor output level. Its operating characteristics are
identical to those of the Model 77B Control
Console, discussed earlier in this section.
Dim
The dim function allows the post-fader
surround monitor output level to be reduced by a fixed amount. Its operating
characteristics are identical to those of the
Model 77B Control Console, discussed
earlier in this section.
Reference Level
The reference level button sets the postfader surround monitor output level to a
preset value. Its operating characteristics
are identical to those of the Model 77B
Control Console, discussed earlier in this
section.
Technical Notes
Loss of Sync
The Model 76DB relies on an external timing reference (sync) source for proper operation. This can be in the form of a word
clock, DARS (AES11), AES3id, bi-level
video, or tri-level video reference signal.
In most cases the sync signal will be connected to the sync input BNC connector
located on the Model 76DB’s back panel. A
configuration setting also allows the signal
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connected to the L/R input of surround
input A to serve as an AES3id timing
reference. Whenever a valid sync signal
has been connected to the Model 76DB
the sync status LED, located on the unit’s
front panel, will light. The sample rate of
the monitor output channels will reflect the
rate of the sync input and, if a video sync
source is utilized, the configured rate.
If a valid sync signal is not present several visual indications will be provided. On
the Model 76DB the sync status LED will
flash. On all connected Model 77B Control Consoles the 4-digit LED display will
cease normal operation, instead alternating between the words no and sync. When
a valid sync signal is again connected the
sync status LED will light steadily. On the
Model 77B units the word sync will momentarily be displayed followed by a brief
display of the monitor output sample rate.
The sample rate will display as 32.0, 44.1,
48.0, 88.2, 96.0, 176.4, or 192.0, reflecting
the impact of the sync source rate and the
Model 76DB’s configuration.
If during normal operation the sync source
changes from one valid rate to another
a visual indication is provided. On the
Model 77B units the new sample rate—
32.0, 44.1, 48.0, 88.2, 96.0, 176.4, or
192.0—will momentarily be displayed.
Any time a valid sync signal is not connected to the Model 76DB the monitor outputs
will automatically revert to an internally
generated sample rate of 48 kHz with no
digital audio content present. This audio
“black” signal will allow most connected
equipment to continue to function correctly,
of course with no meaningful audio signal
present. As soon as a valid sync signal is
again connected to the Model 76DB the
monitor outputs will automatically switch to
Issue 3, June 2009
Page 44
their correct sample rate and audio signals
will again be present.
Power Down
Great care was taken in the Model 76DB’s
design to minimize the chance that clicks,
pops, or other objectionable audio signals
will be present on the monitor outputs.
A power-down circuit supplies the main
microcontroller integrated circuit with an
indication that a power loss is imminent.
When this condition is detected the monitor outputs automatically switch to silent
audio (audio “black”) in preparation of a
complete loss of signal.
Power-Up Messages and
Error Codes
Upon mains power being applied to the
Model 76DB all connected Model 77B
units will go through a power-up sequence.
The sequence starts by each of the individual LEDs lighting in a “walk-through”
sequence. Then the 4-digit display tests
all its LED segments. Finally, a set of
messages provide details on the specific
Model 77B and connected Model 76DB
software versions:
1. Displays 77b
2. Displays Model 77B software version
3. Displays Model 77B unit address
(A1, A2, A3, or A4)
4. Displays 76db
5. Displays Model 76DB main software
version
6. Displays FPGA
7. Displays 76DB’s logic device software
version
Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
After a successful system power-up sequence normal operation will then commence. Should a problem be encountered
during power up one of two error codes
may show on the Model 77B’s 4-digit
display. If Err1 displays it indicates that
communication is not taking place with the
Model 76DB. The most likely cause would
be incorrect wiring of the data pair linking
the two units. Err2 indicates that the Model
76DB is having problems with its internal
logic device. (A high-speed field-programmable gate array (FPGA) serves as the
digital “heart” of the Model 76DB and without it no audio activity can occur.) The only
way to remedy this condition is to first try
removing and reconnecting mains power.
(And that’s a long-shot as to whether that
would accomplish anything.) If the error
code continues to be displayed the Model
76DB must be returned to the factory for
service. Note that for the vast majority of
StudioComm systems neither of these error codes, especially Err2, will ever appear.
sample rate of an input signal can range
from 1/6 to six times the Model 76DB’s
output sample rate, with the additional
restriction that it must be no less than
8 kHz and no more than 216 kHz. The
Model 76DB’s output sample rate is determined by the external timing reference
(sync) signal and, if required, a configured
value. If a word clock, DARS (AES11),
or AES3id signal is the designated sync
source its rate will be the Model 76DB’s
output sample rate. If a video sync signal
is connected, the Model 76DB’s sample
rate is selected as part of the configuration
process.
Sample Rate Conversion
(SRC)
As useful as allowing one disparate sample rate to be converted to another, it may
be the ability of the Model 76DB’s SRC
function to re-synchronize a signal that
proves most valuable. In typical broadcast
applications all signals will have a sample
rate of 48 kHz. A Model 76DB and all its
normally connected input signals will be
“locked” to the main timing reference signal
that supports the 48 kHz sampling rate.
But, as an example, a signal associated
with a portable device, while at a 48 kHz
sampling rate, may not be synchronized
(“genlocked”) to the “house” reference.
Connecting this signal to stereo input C
will cause the SRC function to “lock” it to
the Model 76DB’s rate, thus allowing it to
be monitored over a loudspeaker system.
Circuitry associated with stereo input C
can provide sample rate conversion (SRC)
capability. A digital audio signal connected
to that input can have its sample rate and
timing re-synchronized to match the Model
76DB’s internal clock. While it would be
nice to proclaim that the engineers at
Studio Technologies came up with a
unique and exotic circuit to perform this
function it’s really not the case. Several
semiconductor companies offer “singlechip” SRC solutions and the Model 76DB
uses an excellent one from AKM. The
technical capabilities of the Model 76DB’s
SRC function is stated in this way: the
Model 76DB/77B User Guide
Studio Technologies, Inc.
So in practice what can the SRC function
accomplish? If the output sample rate
is 48 kHz then a signal connected to
stereo input C can have a sample rate
from 8 to 216 kHz. Or, as another example,
if the Model 76DB’s output sample rate is
96 kHz a signal connected to stereo input
C can have its sample rate range from
16 to 216 kHz.
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for Surround
In addition, the stereo input C direct monitor output can be connected to other devices that find need for the now-synchronized
signal. In some cases it may be useful to
connect the stereo input C direct monitor
output to the input of a signal router, allowing an entire facility to access the signal.
Dialnorm
A source of Dolby E metadata can be connected to the Model 76DB Central Controller. Within this flow of metadata frames can
be a “dialnorm” level value that’s associated with one of the Model 76DB’s 5.1
surround input signals. When this surround
input is selected for monitoring its associated dialnorm level value can be displayed
by the Model 77B Control Console. It can
also be used to control the level of the
post-fader surround monitor output.
Technically, the metadata is in the form
of a 115.2 kbit/s RS-485/RS-422 signal
that contains a number of data elements,
including one or more that represent the
average dialog level (dialog normalization or dialnorm) in the audio program
signals being carried over the digital audio
portion of the related Dolby E interface.
These dialnorm levels are associated with
specific programs within the 8-channel
audio “stream.” Firmware within the Model
76DB is able to parse (separate) the data
elements, specifically separating the first
dialnorm level value in the metadata frame
from the one or more that may be present
later in the frame. To clarify, all dialnorm
level elements that occur later in the same
metadata frame are ignored. This method
was selected as it was assumed that the
first dialnorm level element will always be
associated with a 5.1 program. There’s
a technical basis for why this should be
true. In Dolby E a 5.1 program is always
Issue 3, June 2009
Page 46
assigned to the first six channels (channels 1-6). While there may be separate
dialnorm values associated with audio
channels 7 and 8, they are not relevant for
correct StudioComm system operation.
Model 76DB to Control
Console Connections
Figure 6 gives a detailed description of the
signals that connect the Model 76DB Central Controller to the one or more Model
77B or Model 71 Control Consoles. The
Model 76DB provides a +12 volt DC power
source for use by the control console’s
circuitry. The DC output is current-limited
to minimize the chance that a short-circuit
condition will damage the Model 76DB’s
circuitry. An asynchronous, bi-directional
data interface links the connected units.
The RS-485 hardware connection scheme
operates at a rate of 115.2 kbit/s and uses
an 8-N-1 data format. The Model 76DB
communicates with each Model 77B and
Model 71 unit 20-times per second, receiving button and rotary level control information and sending LED and 4-digit display
status data.
“Hot” Disconnection of
Control Consoles
There’s no problem relocating one or more
Model 77B or Model 71 Control Consoles
while the StudioComm system is operating. You can disconnect the 9-pin interconnecting cable, move the unit (or units),
and then reconnect without issue. Upon
disconnection of all control consoles the
Model 76DB Central Controller will mute
the monitor output channels as well as
saving the current operating parameters.
No clicks, pops, or other noises will occur
when the Model 77B or Model 71 units
Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
are again connected. The control consoles
will go through their standard power-up
sequence and then normal operation will
resume.
Channel Status, User, and
Validity Bits
The non-audio bits that are part of the
AES3/AES3id monitor output channel data
are actively controlled by the Model 76DB’s
software. The Channel Status bits use the
Professional Use of Channel Status block.
They indicate a word length of 24 and the
current sample rate. The correct CRC is
also calculated and inserted. The User bits
are always set to 0. When an external timing reference (sync) source is available to
the system the Validity bits will be set to 1.
The Model 76DB’s hardware is capable of
routing the C/U/V bit information from surround input A L/R, stereo input C, and the
sync input to the main logic device (FPGA)
and then on to the digital audio transmitter
(DIT) integrated circuits. This is provided
for future use and is not active at this time.
Model 76DB/77B User Guide
Studio Technologies, Inc.
Issue 3, June 2009
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for Surround
Specifications
Downmix:
Functions: 5.1 to stereo, stereo to mono
Model 76DB Central Controller
5.1 to Stereo: LS @ –3 dB summed with L; RS @
–3 dB summed with R; C @ –6 dB summed with
L and R; LFE @ –6 dB summed with L and R (if
enabled); C, LFE, LS, and RS monitor outputs mute
General Audio:
Supported Sample Rates: 32, 44.1, 48, 88.2, 96,
176.4, and 192 kHz
Word Length: 24 bits maximum
Internal Processing: 32 bits
Dynamic Range: 134 dB
Input-to-Output Latency: one sample (e.g., 0.021
milliseconds @ 48 kHz sample rate)
Digital Audio Inputs: five (18 audio channels)
Configuration: two surround (5.1) and three stereo
(2-channel)
Stereo to Mono: L @ –3 dB summed with R @
–3 dB to C; L, R, LS, RS, and LFE monitor outputs
mute. (For a surround input this results in the C
output being the sum of L @ –3 dB, R @ –3 dB,
C @ –3 dB, LFE @ –3 dB (if enabled), LS @
–6 dB, and RS @ –6 dB.)
Dolby E Metadata Input:
Type: RS-485/RS-422
Data Rate/Format: 115.2 kbit/s, 8-N-1
Type: AES3id-2001/SMPTE 276M (75 ohms,
unbalanced)
Connector: 9-pin D-subminiature female (shared
with remote control inputs)
Connectors: BNC (per IEC 60169-8 Amendment 2)
Control Console Interface:
Type: RS-485, 115.2 kbit/s, 8-1-N
Sample Rate Conversion (SRC):
Application: available on Stereo Input C
Polling Interval: 50 milliseconds
Input Sample Rate Range: 8 to 216 kHz, limited to
1/6 to 6 times the output sample rate
Power: 12 volts DC, 500 milliamperes maximum
Latency: 1 millisecond, nominal
Remote Control Inputs: three
Functions: remote mute all, remote dim, remote
auxiliary monitor output on/off
Sync Input:
Sources: word clock, DARS (AES11), AES3id,
bi-level video, tri-level video
Jitter: 4 ns pp maximum
Connector: BNC (per IEC 60169-8 Amendment 2)
Termination: 75 ohms, selectable on/off
Digital Monitor Outputs: four (16 audio channels)
Configuration: organized as two surround (5.1),
one auxiliary stereo, and one stereo input C direct
output
Type: AES3 (110 ohms/5 Vpp) or AES3id/SMPTE
276M (75 ohms, 1 Vpp), selectable
Connector: 25-pin D-subminiature female
Configurable Delay: 0 to 340 milliseconds @
48 kHz sample rate (scaled up or down depending
on actual sample rate)
Connector: 9-pin D-subminiature female
Type: +5 V logic, activates on closure to system
common
Connector: 9-pin D-subminiature female (shared
with metadata input)
AC Mains:
Requirement: 100 to 230 V, 50/60 Hz, 15 watts
maximum
Connector: 3-blade, IEC 320 C14-compatible
(mates with IEC 320 C13)
Mounting: one space in a standard 19-inch rack
Dimensions:
19.00 inches wide (48.3 cm)
1.72 inches high (4.4 cm)
7.00 inches deep (17.8 cm)
Weight: 6.2 pounds (2.8 kg)
Issue 3, June 2009
Page 48
Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
Model 77B Control Console
Application: up to four Model 77B Control
Consoles can be connected to a Model 76DB
Central Controller
Power: 12 volts DC, maximum current 100 milliamperes, provided by Model 76DB Central Controller
Control Data:
Type: RS-485
Data Rate/Format: 115.2 kbit/s, 8-N-1
Connector: 9-pin D-subminiature female
Dimensions (Overall):
7.20 inches wide (18.3 cm)
2.20 inches high (5.6 cm)
5.40 inches deep (13.7 cm)
Weight: 1.7 pounds (0.8 kg)
Model 71 Control Console
Application: up to three Model 71 Control
Consoles can be connected to a Model 76DB
Central Controller
Power: 12 volts DC, maximum current 35 milliamperes, provided by Model 76DB Central Controller
Control Data:
Type: RS-485
Data Rate/Format: 115.2 kbit/s, 8-N-1
Connector: 9-pin D-subminiature female
Dimensions (Overall):
3.20 inches wide (8.1 cm)
2.20 inches high (5.6 cm)
4.10 inches deep (10.4 cm)
Weight: 0.8 pounds (0.4 kg)
Specifications and information contained in this
User Guide subject to change without notice.
Model 76DB/77B User Guide
Studio Technologies, Inc.
Issue 3, June 2009
Page 49
for Surround
Appendix A—Connection Pin-Out
Charts
Connections
TASCAM® Signal
Channel High (+)
Signal
Pin
Direction
Signal
Low (–)
Shield
Data + (RS-485)
1
To/From Models 77B/71
Pre-Fader L/R
1
24
12
25
Data – (RS-485)
6
To/From Models 77B/71
Pre-Fader C/LFE
2
10
23
11
Data Shield
2
To/From Models 77B/71
Pre-Fader LS/RS
3
21
9
22
DC + (12 V)
4
To Models 77B/71
Stereo Input C Direct
4
7
20
8
DC – (12 V Return)
9
To Models 77B/71
Post-Fader L/R
5
18
6
19
DC Power Shield
5
To/From Models 77B/71
Post-Fader C/LFE
6
4
17
5
Post-Fader LS/RS
7
15
3
16
Auxiliary Stereo
8
1
14
2
Notes: 1) All signals transformer-coupled digital audio;
selectable for AES3 or AES3id compatibility.
2) Connector type on Model 76DB is 25-pin
D-subminiature female (DB-25F). Installer must
provide male (DB-25M). Connector uses 4-40
threaded inserts for locking with mating plug.
Note: Connector type on Model 76DB is 9-pin D-subminiature
female (DE-9F). Connector uses 4-40 threaded inserts
for locking with mating plug.
Connections between Model 76DB and
Model 77B and Model 71
3) Wiring scheme follows TASCAM DA-88 convention.
Standard DA-88-type wiring harnesses are directly
compatible, with the exception of 4-40 screw threads
being required.
Connections for Monitor Outputs
Signal
Pin
Direction
Data + (RS-485/RS-422)
7
Input
Data – (RS-485/RS-422)
2
Input
Data Shield
1
Shield
Remote Mute All
5
Input
Remote Dim
6
Input
Remote Aux Monitor Out On/Off
8
Input
Remote Spare
9
Input
Remote Common
4
Common
Note: Connector type on Model 76DB is 9-pin D-subminiature
female (DE-9F) Connector uses 4-40 threaded inserts
for locking with mating plug.
Connector Pin Outs for Metadata and Remote
Control Inputs
Issue 3, June 2009
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Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
Appendix B—Sync Sources
The Model 76DB’s sync input has been tested and confirmed for correct operation with the
following sync signals:
Word Clock: Square wave signal with rate of 32, 44.1, 48, 88.2, 96, 176.4, or 192 kHz.
DARS (AES11) or AES3id: Signal with sample rate of 32, 44.1, 48, 88.2, 96, 176.4, or
192 kHz.
Video: See table below.
Video Format
Video Format
NTSC (“Black Burst”)
1035i/59.98 Hz
PAL (“Black Burst”)
1035i/60 Hz
525i/59.94 Hz
1080i/50 Hz
525p/59.94 Hz
1080i/59.94 Hz
625i/50 Hz
1080i/60 Hz
625p/50 Hz
1080p/23.98 Hz
720p/23.98 Hz
1080p/24 Hz
720p/24 Hz
1080p/25 Hz
720p/25 Hz
1080p/29.97 Hz
720p/29.97 Hz
1080p/30 Hz
720p/30 Hz
1080psf/24 Hz
720p/50 Hz
1080psf/23.98 Hz
720p/59.94 Hz
720p/60 Hz
Model 76DB/77B User Guide
Studio Technologies, Inc.
Issue 3, June 2009
Page 51
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