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

for Surround Model 76DBA Central Controller and Model 77B Control Console User Guide
for Surround
Model 76DBA Central Controller and
Model 77B Control Console
User Guide
Issue 1, November 2010
This User Guide is applicable for systems consisting of:
Model 76DBA: serial number M76DBA-00151 and later with software version 3.00 and higher;
Model 77B: serial number M77B-00210 and later with software version 3.00 and higher
© 2010 by Studio Technologies, Inc., all rights reserved
www.studio-tech.com
50242-1110, Issue 1
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for Surround
Table of Contents
Introduction ................................................................... 5
Installation .................................................................... 9
Configuration ................................................................19
Operation ......................................................................37
Technical Notes ............................................................45
Specifications ...............................................................49
Appendix A—Connection Pin-Out Charts ....................51
Appendix B—Sync Sources .........................................52
Model 76DBA/77B User Guide
Studio Technologies, Inc.
Issue 1, November 2010
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for Surround
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Model 76DBA/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 76DBA
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 audio material
has become a day-to-day reality, the ability to simply and effectively monitor these
sources is imperative for recording, postproduction, and broadcast facilities. And
with audio-with-picture applications becoming so prevalent, additional monitoring challenges have arisen. Studio Technologies
has addressed these needs with the StudioComm for Surround Model 76DBA Central
Controller and the Model 77B and Model 71
Control Consoles. With digital audio inputs,
digital and analog monitor outputs, Dolby®
E dialnorm support, and an extensive set
of operating 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, configurable input-signal time
delay, multiple digital and analog monitor outputs, downmix and solo functions,
dialnorm display, along with a multi-format
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 needs of broadcast master control
applications.
Model 76DBA/77B User Guide
Studio Technologies, Inc.
A 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
location, allowing fingertip selection of
all monitoring functions. Numerous LED
indicators provide complete status information. A 4-digit numeric display indicates the
post-fader monitor output level 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. Intended for secondary monitoring locations, the Model 71 Control Console is a compact user control surface. It
provides three of the most basic functions:
a rotary level control, dim on/off button,
and reference level on/off button.
While many installations will use only one
Model 77B Control Console, up to three
additional Model 77B or Model 71 Control
Consoles can also be connected. This
provides multiple users with full control
over a facility’s monitor system. And to
make installation simple, the Model 76DBA
provides power for all connected Model
77B or Model 71 units.
The core of this StudioComm for
Surround system is the Model 76DBA
Central Controller. The one-rack-space
unit contains digital audio input, digital
and analog monitor output, processing,
and support circuitry. The Model 76DBA
provides two surround (5.1) and three
stereo digital audio inputs. These unbalanced digital inputs are AES3id/SMPTE
276M-compliant; sources of this type are
ubiquitous in most post-production and
broadcast environments. The inputs allow
a sample rate of up to 192 kHz and a bit
depth of up to 24 to be directly supported.
Circuitry associated with one of the stereo
inputs provides sample rate conversion
Issue 1, November 2010
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for Surround
(SRC) capability, allowing a wide range of
digital audio sources to be monitored. Up
to 340 milliseconds of input delay can be
selected to compensate for processing
delays in an associated video path. A number of different signals can serve as the
Model 76DBA’s digital audio timing reference. For synchronization with a master
timing reference a dedicated source of
word clock, DARS (AES11), bi-level video,
or tri-level video can be connected. Alternately, the L/R connection of the actively
selected surround or stereo input source
can serve as the timing reference.
functions. The auxiliary stereo digital and
analog outputs are provided for special
broadcast applications where independent
outputs with separate on/off control are
desired. The stereo input C direct digital
monitor output allows an installation to
directly access the SRC capabilities.
For installation flexibility the digital monitor
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 impedance
is 110 ohms with a signal level of 5 volts
peak-to-peak (Vpp). For AES3id operation
the impedance is 75 ohms and the level
is 1 Vpp.
A range of digital and analog surround
(5.1) and stereo monitor outputs are provided. The post-fader surround digital
and analog monitor outputs are intended
for connection to monitor loudspeaker
systems. The pre-fader surround digital
monitor output can be used with metering
systems that require signals that aren’t impacted by level control or other monitoring
A source of Dolby E metadata can be connected to the Model 76DBA 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
Figure 1. Model 76DBA Central Controller Front Panel
Control console
status LED
Metadata
status
LED
Sync
status
LED
Figure 2. Model 76DBA Central Controller Back Panel
AC mains
input connection
To/from
Models 77B &
71 Control
Consoles
RS-485 and
remote control
inputs
Issue 1, November 2010
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Digital
monitor
output
connections
Analog
monitor outputs
Sync
Input
connection
Surround Input B
connections
Stereo
Input C
connection
Stereo Input A and
Stereo Input B
connections
Surround Input A
connections
Model 76DBA/77B User Guide
Studio Technologies, Inc.
for Surround
Channel solo
Auxiliary stereo
monitor output
enable
Downmix
Display mode
Dialnorm and
monitor output
level display
Input select
Figure 3. Model 77B Control Console Front Panel
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 76DBA 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 digital and analog monitor output
levels. This provides a unique solution for
the broadcast and post-production world,
allowing a professional environment to accurately simulate an end user’s experience.
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.
Model 76DBA/77B User Guide
Studio Technologies, Inc.
Post-fader surround
digital and analog monitor
outputs
• Dialnorm enable
• Reference level
• Mute all
• Dim
• Rotary level control
The Model 76DBA occupies one space
(1U) in a standard 19-inch rack. Digital
audio sources are interfaced with the
Model 76DBA using nine BNC connectors.
A tenth BNC connector is used by the sync
source. Digital and analog monitor output
signal connections are made using two
25-pin D-subminiature connectors. One
9-pin D-subminiature connector is used to
connect the Model 76DBA 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. AC mains power
is connected directly to the Model 76DBA,
with an acceptable range of 100 to 230
volts, 50/60 Hz.
Additional Details
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
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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.
The post-fader surround digital and analog
monitor output levels 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 digital and analog
monitor output channels to automatically
mute whenever the output level control
reaches maximum attenuation. Using the
reference level function, the post-fader
surround digital and analog monitor output
levels 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 postfader surround digital and analog 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 digital and analog monitor output
levels to be reduced by a fixed dB amount.
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The dim level is configured from among
four available values. A mute all function allows the post-fader surround digital
and analog monitor output channels to be
simultaneously muted. The channel solo
section provides post-fader surround digital and analog 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 postfader surround digital and analog monitor
output channel to be raised while the level
of the other channels is reduced. This helps
to emphasize the content on one channel
without fully muting the others. Broadcast
applications can benefit from the channel
pop solo mode by 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
digital and analog monitor outputs. A
configuration setting allows the pre-fader
Model 76DBA/77B User Guide
Studio Technologies, Inc.
for Surround
surround digital monitor output to be
selected for pre- or post-downmix
operation.
In addition to the surround digital and
analog monitor outputs, auxiliary stereo
digital and analog monitor outputs are
also provided. A stereo signal, connected
to stereo input C on the Model 76DBA
Central Controller, can be routed to the
auxiliary stereo digital and analog monitor
outputs. 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 stereo digital
and analog monitor outputs 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 systems, on-air or recording tally
signals, and audio consoles. Three remotecontrol inputs provide access to the mute
all, dim, and auxiliary stereo monitor output on/off functions. 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 digital and analog
monitor outputs or enable the auxiliary
stereo digital and analog monitor outputs.
Installation
In this section you will be installing the
Model 76DBA Central Controller in an
equipment rack. Connections to the digital
audio inputs and digital and analog monitor
outputs will be made. A dedicated digital
Model 76DBA/77B User Guide
Studio Technologies, Inc.
audio timing reference signal can
be connected to the sync input. 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 76DBA. AC mains
power will be connected to the Model
76DBA. For advanced applications up to
three additional Model 77B or Model 71
Control Console units can be connected
to the Model 76DBA.
System Components
The main shipping carton contains one
each of the following: Model 76DBA
Central Controller, Model 77B Control
Console, 9-pin D-sub interconnecting
cable, and user guide. Also included in
the shipping carton is a North Americanstandard AC mains cord. Your dealer or
distributor should provide an AC mains
cord appropriate for destinations outside
of North America. Any additional Model
77B or Model 71 Control Consoles will be
shipped in separate cartons.
Mounting the Model 76DBA
The Model 76DBA Central Controller
requires one space (1U) in a standard
19-inch (48.3 cm) equipment rack. Secure
the Model 76DBA into the equipment rack
using two mounting screws per side.
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 76DBA to
the Model 77B. If the needs of a specific
installation dictate, an alternate-length
interconnecting cable can be fabricated
and used.
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Audio Connections
Audio connections are made by way
of nine BNC jacks and two 25-pin
D-subminiature connectors. All the connectors are located on the Model 76DBA’s
back panel. Refer to Figure 2 for a detailed
view of these jacks and the connector.
Digital Audio Inputs
Two surround (5.1) and three stereo
digital audio sources can be connected.
All sources can be monitored using the
pre- and post-fader surround digital and
analog monitor output channels. A one-toone relationship is maintained between the
input 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 one
or both of the downmix functions.) Stereo
input C is also routed to the stereo input C
direct digital and analog monitor outputs.
The digital audio inputs support digital
audio signals with a sampling rate of up to
192 kHz and a word length (depth) of up
to 24 bits. It’s best if the connected signal
sources maintain a common sample rate
and timing reference. Having all signals
“locked” together helps to ensure proper
handling by the Model 76DBA’s all-digital
signal control 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. A signal
connected to stereo input C can have an
independent sample rate and timing reference and still be monitored correctly. Refer
to the Technical Notes section of this guide
for a detailed review of the SRC capability.
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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
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
2-channel 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 digital and
analog 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 digital and analog
monitor outputs.
In addition, the signal connected to stereo
input C will be routed to the auxiliary stereo
digital and analog monitor outputs whenever that function is active. To clarify: if the
auxiliary stereo digital and analog monitor outputs are enabled a signal on the left
channel of stereo input C will be present on
the left channel of the auxiliary stereo monitor outputs; a signal on the right channel of
stereo input C will be present on the auxiliary stereo monitor outputs’ right channel.
Stereo input C is also routed to the stereo
input C direct digital monitor output. A oneto-one channel mapping scheme is maintained. The signal present on the stereo
input C direct digital 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.
Model 76DBA/77B User Guide
Studio Technologies, Inc.
for Surround
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 source. Its left and right channels can’t be independently monitored over
the center channel of the surround monitor outputs. (The configuration function
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 stereo digital and analog
monitor outputs. It follows a left-in-to-leftout, right-in-to-right-out scheme.
Nine BNC jacks on the Model 76DBA’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
with unbalanced digital audio sources that
are compatible with the AES3id standard.
In broadcast or post-production 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.
Balanced AES3 digital audio signals can
also be used with the Model 76DBA’s
inputs if external coupling transformers
(“baluns”) are utilized. These impedancematching (110 ohms to 75 ohms) and
level-attenuating transformer assemblies
typically provide a 3-pin female XLR connector on their input and a female BNC
connector on their output.
Model 76DBA/77B User Guide
Studio Technologies, Inc.
Digital Monitor Outputs
The 25-pin D-subminiature connector
labeled Digital Monitor Outputs provides
access to the Model 76DBA’s 16 channels
of digital audio monitor output: pre-fader
surround, post-fader surround, auxiliary
stereo, and stereo input C direct. The prefader surround digital monitor output
channels are intended for connection to
metering or monitoring equipment that
requires uninterrupted full-level signals. The
post-fader surround digital monitor output
channels are intended to connect to a 5.1
loudspeaker system.
The auxiliary stereo digital monitor output is
provided to support a separate set of stereo
monitor loudspeakers, the primary application intended to allow monitoring of interor intra-facility communications.
The stereo input C direct digital 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 76DBA’s configuration settings.
For flexibility the digital monitor outputs
are transformer-coupled and can be configured to act as AES3 or AES3id digital
audio sources. The digital monitor outputs
are configured in two groups with separate
choices available for the pre-fader surround/
stereo input C direct group and post-fader
surround/auxiliary stereo 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 shielded twisted-pair
cable terminated with 3-pin XLR connectors. When a group is configured for AES3id
(75 ohms/1 Vpp) the source impedance and
Issue 1, November 2010
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signal level are compatible with the requirements of AES3id interfacing. These signals
are typically interconnected using coaxial
cable terminated with BNC connectors. For
details on how a Model 77B Control Console
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 supplying two audio channels.
A wiring assembly prepared for the Model
76DBA’s digital 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 3-pin
male XLR connectors on the other. A wiring
assembly prepared for the Model 76DBA’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 + terminal would go to pin 2 of the XLR, the – terminal to XLR pin 3, and the shield terminal to
XLR pin 1.
Issue 1, November 2010
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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.
To clarify, for optimal operation it is best
to connect both the – and shield connections together directly on the D-sub plug,
rather than at the BNC end of the interface
assembly. Note that the output circuitry is
transformer-coupled 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
76DBA’s D-sub connectors use 4-40
threads. This complies with the original
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 76DBA 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 possible exception of 4-40 screw
threads being required.
Figure 4. Connections for Digital Monitor
Outputs
Model 76DBA/77B User Guide
Studio Technologies, Inc.
for Surround
design standard for D-subminiature
connectors.
Pre-Fader Surround Digital Monitor
Output
The pre-fader surround digital monitor
output channels are intended to connect
to metering, measurement, or other signal
monitoring equipment that requires uninterrupted, full-level digital audio signal
sources.
Stereo Input C Direct Digital Monitor
Output
The stereo input C direct digital monitor
output is intended for use in site-specific
applications. It provides an uninterrupted,
full-level digital audio signal source that
is post-SRC and input delay in the signal
chain.
Post-Fader Surround Digital Monitor
Output
The post-fader surround digital monitor
output channels are designed for connection to digital inputs on audio amplifiers
associated with monitor loudspeakers.
Alternately, they could be connected to the
inputs of loudspeakers that contain integrated amplifiers with digital audio input
capability.
Auxiliary Stereo Digital Monitor Output
The auxiliary stereo digital monitor
output channels are intended to support
a stereo loudspeaker system, either by
connecting to the digital input of an amplifier associated with a set of loudspeakers
or directly to a set of amplified speakers
that provide digital inputs. In either case
a user level control must be provided. The
StudioComm system is not, by design,
able to control the level of the auxiliary
stereo digital monitor output.
Model 76DBA/77B User Guide
Studio Technologies, Inc.
Analog Monitor Outputs
The connector labeled Analog Monitor
Outputs provides access to the Model
76DBA’s 6-channel (5.1) post-fader
surround and 2-channel auxiliary stereo
monitor outputs. The post-fader surround
analog monitor output channels are intended to connect to analog inputs associated
with the surround loudspeaker system incorporated in a facility. The auxiliary stereo
analog monitor output allows support for
a secondary set of stereo monitor loudspeakers. The StudioComm system is not,
by design, able to control the level of the
auxiliary stereo analog monitor output. As
such, the loudspeaker system must contain a means of adjusting its output level.
The analog monitor output channels are
designed for connection to audio amplifiers
associated with monitor loudspeakers or
to the inputs of loudspeakers that contain
integrated amplifiers. The analog monitor
outputs are electronically balanced and
will perform optimally when driving loads
of 2000 (2 k) ohms or greater. In most
applications 3-pin XLR plugs (male) will
be used to interface with the inputs on the
associated amplifiers or amplified speakers. In this case the + terminal would go to
pin 2 of the XLR, the – terminal to XLR
pin 3, and the shield terminal to XLR pin 1.
Balanced operation of the analog monitor
outputs is the preferred connection method
but unbalanced operation does not pose a
problem. To connect to an unbalanced load
connect the + terminal as signal high, and
only the Model 76DBA’s shield terminal as
the signal low/shield. Leave the – terminal
unconnected. For correct unbalanced
operation, it is important not to connect
– and shield together.
Issue 1, November 2010
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The wiring scheme used by the D-subminiature connector complies with that made
popular by TASCAM® with their DA-88®
product. A wiring assembly prepared for
the Model 76DBA’s analog monitor outputs
is identical to that of a DA-88-style output
assembly. Please refer to Figure 5 or
Appendix A for the exact connection details. Again note that unlike a DA-88-style
assembly, the Model 76DBA’s D-sub
connectors use 4-40 threads.
Signal
High (+)
Signal
Low (–)
Shield
Surround L
24
12
25
Surround R
10
23
11
Surround C
21
9
22
Surround LFE
7
20
8
Surround LS
18
6
19
Surround RS
4
17
5
Auxiliary Stereo L
15
3
16
Auxiliary Stereo R
1
14
2
Connections
Notes: 1) Connector type on Model 76DBA 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.
2) 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 5. Connections for Analog Monitor
Outputs
Sync Input
The Model 76DBA requires a timing reference (sync) signal so that the digital audio
input and digital monitor output signals will
be handled correctly. A configuration setting allows the source of sync to be the
L/R input of the currently selected surround or stereo digital audio input. While
this is acceptable, audio artifacts (clicks or
noise) can occur when switching between
inputs. A better method is to connect a
Issue 1, November 2010
Page 14
dedicated timing reference signal to the
Model 76DBA’s sync input connector. The
connected sync signal must maintain a
stable relationship between itself and the
digital audio inputs. The actual sync source
can be in one of several formats: word
clock, DARS (AES11), bi-level video, or
tri-level video.
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
were originally provided to support NTSC
and PAL broadcast applications, although
they continue to be used by contemporary equipment. Tri-level sync signals
were primarily associated with facilities
that supported high-definition (HD) video
equipment however the importance of this
type of sync seems to be waning. Both
bi-level and tri-level signals can be found
at numerous rate combinations, configured
to allow for compatibility with the various
video formats.
With the wide range of allowable sync
sources proper Model 76DBA 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 is connected to the sync input BNC connector
located on the Model 76DBA’s back panel.
Model 76DBA/77B User Guide
Studio Technologies, Inc.
for Surround
For flexibility this 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 76DBA’s sync input will typically
have input termination enabled. If the sync
signal connected to the Model 76DBA 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.
Metadata Input
The Model 76DBA allows a source of
Dolby E metadata to be directly connected.
Hardware and software inside the Model
76DBA 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 digital and analog
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 76DBA. Refer to Figure 6 or 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
Model 76DBA/77B User Guide
Studio Technologies, Inc.
(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 Miranda®.
While in hardware the Model 76DBA’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 76DBA’s metadata input.
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 76DBA.
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 Stereo Monitor Out On/Off
8
Input
Remote Spare
9
Input
Remote Common
4
Common
Note: Connector type on Model 76DBA is 9-pin D-subminiature
female (DE-9F) Connector uses 4-40 threaded inserts
for locking with mating plug.
Figure 6. Connections for Metadata and Remote
Control Inputs
Issue 1, November 2010
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for Surround
Remote Control Inputs
Support is provided for three remote
control input functions: remote mute all,
remote dim, and remote auxiliary stereo
monitor output on/off. Note that the remote
mute all and remote dim functions only
impact the post-fader surround digital and
analog monitor outputs.
The Model 76DBA’s 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 6 or Appendix A for the exact
connection details. Note that pin 4 (remote
common) connects to the Model 76DBA’s
internal circuit common connection as
well as to the Model 76DBA’s chassis and
mains earth connections. Figure 6 also
shows one spare remote control input
(pin 9). This is provided for future applications and should remain unconnected.
Connecting the Model 76DBA
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
76DBA Central Controller. This is used to
interface the unit with Model 77B Control
Consoles. Refer to Figure 7 or Appendix A
for details. A 9-pin female D-sub connector,
Issue 1, November 2010
Page 16
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 76DBA is 9-pin D-subminiature
female (DE-9F). Connector uses 4-40 threaded inserts
for locking with mating plug.
Figure 7. Connections between Model 76DBA
and Model 77B and Model 71
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 (DE-9M) connectors on each end is
used to interconnect the Model 76DBA 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
76DBA’s connector pin-out 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.
Model 76DBA/77B User Guide
Studio Technologies, Inc.
for Surround
A few simple calculations are required to
determine the maximum cable length when
connecting a Model 76DBA to a Model
77B. 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 76DBA to a Model 77B. The
Model 76DBA supplies 12 volt DC with a
maximum current of 500 milliamperes.
The Model 77B requires a minimum of
9 volts DC, 100 milliamperes, 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
76DBA 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 required current in amperes).
Remember to include the resistance in
both the DC + and DC – wires when calculating the voltage drop. 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 76DBA’s ability to be controlled by
additional control consoles. At least one
Model 77B Control Console must be connected to the Model 76DBA Central Controller. After this requirement has been met
Model 76DBA/77B User Guide
Studio Technologies, Inc.
up to three additional Model 77B or Model
71 Control Consoles can also be connected and powered by the Model 76DBA.
When connecting multiple control consoles
to a Model 76DBA all nine pins of each
interconnecting cable can be connected in
parallel (multed). Using this arrangement
the data and 12 volt DC power signals between all the units will be multed. 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 76DBA to Model 77B cable length
are discussed. Note the required current
for a Model 77B is 100 milliamperes while
a Model 71 requires only 35 milliamperes.
It’s important to review this information
prior to creating the interconnection
scheme to be used for installing multiple
Model 77B units.
AC Mains Power
The Model 76DBA 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 5-15L) on one end and an
Issue 1, November 2010
Page 17
for Surround
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 76DBA
does not contain an AC mains disconnect switch; 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 76DBA 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 LEDs will flash in cadence while the
firmware loads into the Model 76DBA’s
main logic device. After just a few seconds
initial system operation will commence and
the three LEDs will perform their intended
functions. Once operating data is being
interchanged with the one or more connected Model 77B or Model 71 Control
Consoles the control console status LED
will also 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 valid sync
source has been recognized. The sync
status LED will flash if a valid sync source
is not recognized.
Issue 1, November 2010
Page 18
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 main and logic
device software versions of the associated
Model 76DBA.
All connected Model 71 units will also go
through a power-up sequence after mains
power is applied to the Model 76DBA.
Each of the Model 71’s three LEDs will
light momentarily. After these LEDs have
been lit, the device address will be shown
briefly using the dim and reference level
LEDs, as shown in Figure 8 in the Operation section. When this is complete the
Model 71 will begin normal operation and
its status LED will light if communication is
established with the Model 76DBA. 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 two LEDs on the
Model 76DBA’s front panel will continue
to flash in cadence indefinitely. On the
Model 77B units a diagnostic code may
be displayed. Refer to the Technical Notes
section of this user guide for details.
Only after the Model 76DBA and all
connected Model 77B and Model 71 units
have correctly powered up will full system
operation begin. It’s possible that audio
signals will first be present on the digital
monitor outputs. The analog monitor outputs will only become active after a protection interval has elapsed. These outputs
are muted using electro-mechanical relays
that operate under software control.
Model 76DBA/77B User Guide
Studio Technologies, Inc.
for Surround
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
76DBA 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.
However, 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. A 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 (unique for
each unit)
• Stereo Input C Sample Rate Converter
• Auxiliary Monitor Output Nominal Level
• Sync Source
• Sync Input Termination
• Audio-Synced-to-Video Sample Rate
• Digital Monitor Output Types
• Input Select Buttons
• Reference Level
• Overall Display Mode
• Reference Level in dB SPL
Model 76DBA/77B User Guide
Studio Technologies, Inc.
• Auto Reference Level Off
• Dialnorm Reference Level
• Dialnorm-Data-to-Surround-Input
Assignment
• Dim Level
• Remote Inputs
• Input Delay
• LFE Downmix Mode
• Pre-Fader Surround Digital Monitor
Output Mode
• Channel Pop Solo Mode Offset Levels
The 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 its 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 76DBA
into their configuration modes. Other connected Model 77B and Model 71 units will
enter a standby mode. When the Model
76DBA enters its configuration mode it will
immediately mute the digital and analog
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.
As a user aid, a Model 77B that has entered the configuration mode will have its
Issue 1, November 2010
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for Surround
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 to be made on the Model
77B unit that’s in its configuration mode;
press and hold its configure the 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
76DBA Central Controller as well as the
Model 77B and Model 71 Control Consoles. However, only the individual device
address is stored in each Model 77B and
Model 71. All other configuration parameters are stored in the Model 76DBA.
Issue 1, November 2010
Page 20
Model 77B Device Address
A unique device address must be assigned
to each Model 77B that is connected to
a Model 76DBA. 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)
for digital audio signals connected to
that input. 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 with respect with the others
connected to the Model 76DBA, 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
Model 76DBA/77B User Guide
Studio Technologies, Inc.
for Surround
remain enabled. However there might be
special cases where this resource isn’t
desired and it can be disabled.
Auxiliary Stereo Monitor
Output Nominal Level
The nominal level of the auxiliary stereo
digital and analog monitor outputs can be
configured to match the requirements of
a specific installation. Devices connected
to the auxiliary stereo digital and analog
monitor outputs 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
stereo digital and analog monitor outputs
are 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 Source
The Model 76DBA requires that the designated external timing reference (sync) 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
the L/R input of the currently selected surround or stereo digital audio input to serve
as the system’s sync source.
Model 76DBA/77B User Guide
Studio Technologies, Inc.
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 76DBA then
enabling termination is typically appropriate. However, 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 76DBA’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 Digital Monitor
Output Type
To meet the needs of specific installations
the nominal impedance and level characteristic of the pre-fader surround and
stereo input C direct digital monitor outputs
can be selected. They are selected as a
group; configuration of individual digital
outputs is not provided. If the digital output
signals are going to be connected to balanced AES3 inputs then the setting that
provides a source impedance of 110 ohms
and a nominal 5 Vpp output level would
be appropriate. If the digital output signals
are going to be connected to unbalanced
Issue 1, November 2010
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for Surround
AES3id inputs then the setting that provides a 75 ohm source impedance and
a nominal output level of 1 Vpp would be
correct.
Post-Fader Surround/
Auxiliary Stereo Digital
Monitor Output Type
The source impedance and output level
of the post-fader surround and auxiliary
stereo digital monitor outputs, as a group,
can be configured. The information previously provided concerning configuring the
pre-fader surround/stereo input C direct
digital 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 76DBA has connections
for two surround (5.1) and three stereo
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 non-stereo 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 surround 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.
Issue 1, November 2010
Page 22
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 digital and analog monitor
output level to be 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 (digital
and analog) will mute. Press and hold
the reference level button; its associated LED will begin to flash. After five
Model 76DBA/77B User Guide
Studio Technologies, Inc.
for Surround
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.
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.
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 76DBA’s nonvolatile
memory. Only by repeating the entire
procedure can the value be changed.
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.
Once the configuration mode has been
exited, the digital and analog 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 digital and analog monitor output levels in either an attenuation mode
Model 76DBA/77B User Guide
Studio Technologies, Inc.
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 post-fader
surround digital and analog monitor outputs are at their 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,
Issue 1, November 2010
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for Surround
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.
Auto Reference Level Off
When auto reference level off is enabled,
the function automatically turns the reference level function off if a change is made
to the rotary level control while the reference level function is active.
Dialnorm Reference Level
The dialnorm reference level parameter is
provided so that the StudioComm system
can be configured to match a facilities’ or
“plant” default dialnorm level. This value
is used as a reference against which the
post-fader surround digital and analog
monitor output levels 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.
Issue 1, November 2010
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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 digital and analog
monitor output levels by a preset amount.
The reduction is in dB relative to the postfader surround digital and analog monitor
outputs’ 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
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 Stereo
Monitor Output On/Off
This function configures whether the on/off
status of the auxiliary stereo digital and
analog monitor outputs can be controlled
using the remote control input.
Model 76DBA/77B User Guide
Studio Technologies, Inc.
for Surround
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 in 1-millisecond steps.
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.
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 currently
selected 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 digital and analog LFE
output channels will still mute when 5.1 to
stereo downmix is active.
Model 76DBA/77B User Guide
Studio Technologies, Inc.
Pre-Fader Surround Digital
Monitor Output Mode
The pre-fader surround digital monitor
output can be configured as to its place
in the Model 76DBA’s signal flow. The
choices are pre- or post-downmix. In the
pre-downmix mode the digital monitor output channels will not be impacted by the
state of the downmix functions. This setting
would be appropriate if the pre-fader digital 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 digital monitor output
signals. If the post-downmix mode is
selected the pre-fader surround digital
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
digital monitor outputs. In this scenario an
operator would want to visually observe
the actions that the downmix functions
impart on the signals.
Channel Pop Solo Mode
Offset Levels
Two parameters can be configured that
determine how the channel pop solo function impacts 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.
Issue 1, November 2010
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for Surround
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!
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; Model 77B’s units have a
default device address of A1. This ensures
that, in most cases, no change will have
to be made. Refer to Figures 8 and 9 for
details.
A small button is located on the back of
each Model 71 Control Console, adjacent
to the 9-pin D-sub connector. Pressing and
holding this button for two seconds places
this specific unit in its configuration mode;
normal operation of the Model 76DBA 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
Issue 1, November 2010
Page 26
Figure 8. 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 9. Model 71 Device Address Chart
the Model 71’s current device address.
The rotary level control is used to select
the desired device address; the LEDs will
respond accordingly.
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 76DBA/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 76DBA/77B User Guide
Studio Technologies, Inc.
Issue 1, November 2010
Page 27
for Surround
Configuration—Model 77B Device Address, Stereo Input C
Sample Rate Converter, and Auxiliary Stereo Digital and Analog
Monitor Outputs 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
stereo digital and analog monitor outputs
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 stereo digital and analog monitor outputs.
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 stereo digital and analog monitor outputs 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 76DBA.
Issue 1, November 2010
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Model 76DBA/77B User Guide
Studio Technologies, Inc.
for Surround
Configuration—Sync Source, Sync Input Termination, AudioSynced-to-Video Sample Rate, and Digital 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
digital 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 stereo
digital 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 source:
LED Group 1-3 lit means sync input, video
LED 1/4 lit means sync input, DARS
LED 2/5 lit means sync input, word clock
LED 3/6 lit means L/R of currently selected input
Default:
and hold the Mute All button
 Press
to display and select the sync
source, sync input termination,
audio-synced-to-video sample
rate, and digital monitor output types.
Sync source is L/R of currently selected input.
Sync input terminated.
Audio-synced-to-video sample rate 48 kHz.
Pre-fader surround/stereo input C direct digital monitor output type AES3 (110 ohms/5 Vpp).
Post-fader surround/auxiliary stereo digital monitor output type AES3 (110 ohms/5 Vpp).
Model 76DBA/77B User Guide
Studio Technologies, Inc.
Issue 1, November 2010
Page 29
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 1, November 2010
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Model 76DBA/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:
–60.0 dB post-fader surround digital and analog reference 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 76DBA/77B User Guide
Studio Technologies, Inc.
Issue 1, November 2010
Page 31
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 1, November 2010
Page 32
Model 76DBA/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 76DBA/77B User Guide
Studio Technologies, Inc.
Issue 1, November 2010
Page 33
for Surround
Configuration—Dim Level, Remote Mute All, Remote Dim,
Remote Auxiliary Stereo 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 stereo monitor output
on/off. LED not lit means remote auxiliary stereo 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. The value
is scaled 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 stereo
monitor output on/off, and input delay.
–20 dB dim level.
Remote mute all enabled.
Remote dim enabled.
Remote auxiliary stereo monitor output on/off enabled.
Input delay 0 ms.
Issue 1, November 2010
Page 34
Model 76DBA/77B User Guide
Studio Technologies, Inc.
for Surround
Configuration—Channel Pop Solo Mode Offset Levels, LFE
Downmix Mode, and Pre-Fader Surround Digital 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 digital
monitor output
mode.
When the 5.1 to Stereo button is pressed, these
LEDs display the configuration of the pre-fader
surround digital 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 digital monitor output pre-downmix.
Model 76DBA/77B User Guide
Studio Technologies, Inc.
Issue 1, November 2010
Page 35
for Surround
Configuration—Restore Factory Defaults
and hold both the Dialnorm Enable and Dim buttons for 5 seconds to restore Model 77B
 Press
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 stereo digital and analog monitor output
nominal level.
Sync source is L/R of currently selected input.
Sync input terminated.
Audio-synced-to-video sample rate 48 kHz.
Pre-fader surround/stereo input C direct digital monitor
output type AES3 (110 ohms/5 Vpp).
Post-fader surround/auxiliary stereo digital 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.
–60.0 dB post-fader surround digital and analog
reference 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 stereo digital and analog 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 digital 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 1, November 2010
Page 36
Model 76DBA/77B User Guide
Studio Technologies, Inc.
for Surround
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.
Upon power up the system will return to
the last operating condition, including the
selected source, downmix modes, etc.
As a precaution, however, the post-fader
surround digital and analog monitor output
levels will always return to their minimum
value. The rotary level control or the reference level button must then be used to
return the system to the desired monitor
output level.
Model 76DBA Central
Controller
The Model 76DBA’s front panel contains
three LEDs. The control console status
LED will light whenever the Model 76DBA
is communicating with the one or more
connected Model 77B or Model 71 units.
A flashing control console status LED will
indicate 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 powerup 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 76DBA. A flashing
sync status LED indicates that a valid sync
signal is not being received.
Model 76DBA/77B User Guide
Studio Technologies, Inc.
Control Consoles
StudioComm for Surround operation is
controlled using the up to four Model 77B
or Model 71 Control Consoles that have
been connected. Two system functions can
also be controlled by means of the remote
control inputs.
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 stereo
monitor outputs, display and display mode,
and remote control inputs.
Any change made to any one Model 77B
unit will be reflected in the LEDs and displays on all the connected units. Note that
all control consoles 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
Issue 1, November 2010
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between groups will switch between two
specific inputs. This allows rapid switching
between, for example, input 1 and input 6.
The specific sources assigned to the input
buttons depend on the signals connected
to the Model 76DBA along with how the
system has been configured. Any input
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. 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 digital and
analog monitor outputs. And, depending on
the selected configuration, they may also
impact the pre-fader surround digital monitor output. Please refer to the Specifications
section of this guide if you’d like a detailed
description of 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 surround input A or B
is selected.
Issue 1, November 2010
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The Model 77B associates the state of
the downmix functions with the currently
selected input. For example, if surround
input A is the selected input source and
the 5.1 to stereo downmix function is enabled, this condition will be “remembered”
when switching to one of the stereo input
sources. Upon returning to surround input
A, the 5.1 to stereo downmix function will
again become active.
5.1 to Stereo
When the 5.1 to stereo downmix function
is enabled the LS, RS, and C channels
associated with a surround source 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 digital and analog monitor
output channels. The C, LFE, LS, and RS
digital and analog 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 mono downmix function
combines the L and R audio channels to
create a single-channel monaural signal.
This signal is sent out the C surround
digital and analog monitor output channels
while the L, R, LS, RS, and LFE digital and
analog 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
Model 76DBA/77B User Guide
Studio Technologies, Inc.
for Surround
by folding down all channels associated
with the selected surround input.
Monitor Output General
Functions
Four buttons and one rotary control are
associated with the post-fader surround
digital and analog 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 post-fader
surround digital and analog monitor output
levels. These buttons and the rotary control
do not impact the pre-fader surround
and stereo input C direct digital monitor
outputs.
Reference Level
The reference level button sets the postfader surround digital and analog monitor
output levels 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. 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 LED associated with the reference
level button can also serve as a calibration aid. If the reference level mode is not
active, whenever the post-fader surround
digital and analog monitor output levels are
precisely the same as that stored for the
reference value the reference level LED
will flash. This exact level can be reached
Model 76DBA/77B User Guide
Studio Technologies, Inc.
through the use of the rotary level control,
either by itself or through the setting of
the rotary level control in conjunction with
the dim function. Whatever path the postfader surround digital and analog monitor
outputs 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
output channels associated with the postfader surround digital and analog monitor
outputs 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
digital and analog monitor output levels
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 post-fader
surround digital and analog monitor output
levels. If the requested “dimmed” output
level is equal to or less than –96.0 dB, the
post-fader surround monitor outputs will go
into full mute and the display will show four
dashes (– – – –). When dim is active the
post-fader monitor output level reduction
will apply no matter whether the level is
Issue 1, November 2010
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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.
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, and the rotary level control is
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 heart-stopping 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 the 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
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the post-fader surround digital and analog
monitor output levels 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 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 digital
and analog monitor output levels. The
level control provides the ability to adjust
the post-fader surround digital and analog
monitor output levels over a 70 dB range.
Technically the rotary level control is a 24step-per-revolution mechanical encoder.
Model 76DBA/77B User Guide
Studio Technologies, Inc.
for Surround
The amount of level change in dB per
step (“click”) will depend on how quickly
the control is turned. When rotated 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 five full turns. But the Model
77B’s software detects when the control
is rotated more quickly and increases the
amount of level 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
digital and analog monitor output channels will automatically mute. As previously
discussed, the 4-digit display indicates the
mute condition by showing four dashes
(– – – –).
If the mute all function is active the rotary
level control won’t have an impact on the
post-fader surround digital and analog
monitor output levels. It’s also not active
whenever the reference level function is
active, except if the auto reference level
off function has been enabled.
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 digital and
analog monitor outputs, taking place electrically “after” the source selection, input
delay, downmix, and level control functions.
Two solo modes are available, normal and
channel pop. In the normal solo mode
Model 76DBA/77B User Guide
Studio Technologies, Inc.
the level of a channel selected for soloing
actually doesn’t change; the solo function
causes the non-soloed post-fader surround
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 stereo 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 pressto-enable/press-to-disable “latching” mode.
The LED associated with a soloed channel
is used to indicate that solo is active.
The auxiliary stereo digital and analog
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 stereo digital
and analog monitor output enable button
for a few seconds until 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.
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for Surround
For user flexibility, more than one output
channel can be selected for soloing at a
time. The Model 77B even allows all six
surround digital and analog 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.
Auxiliary Stereo Monitor
Outputs
As has been previously discussed in this
user guide, the auxiliary stereo digital
and analog monitor outputs are stereo
(2-channel) outputs that can be used for
special applications. The source for these
outputs is stereo input C. Using the auxiliary stereo monitor output enable button stereo input C can be routed to these
outputs as desired. The button functions in
an alternate action manner to change the
current state of the outputs. An associated
LED lights whenever the auxiliary stereo
digital and analog monitor outputs are
active. No level control, downmix, or other
Model 77B-supported functions will impact
the auxiliary stereo monitor outputs.
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Display and Display Mode
The Model 77B’s 4-digit LED display can
be selected to show either the level of the
post-fader surround digital and analog
monitor outputs 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 76DBA’s current sample
rate.
Both level 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
digital and analog monitor output levels
will be shown as either the amount of
attenuation or the sound pressure level
(SPL).
Display in dB of Attenuation
If configured for the attenuation mode the
display will show the post-fader surround
digital and analog monitor output levels
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 digital and analog
monitor outputs are set to be 40.5 dB
below the maximum level. As the rotary
level control is turned 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 digital and analog monitor output levels in dB SPL, the
4-digit display will always show the output
level in positive numbers. These numbers
Model 76DBA/77B User Guide
Studio Technologies, Inc.
for Surround
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 surround loudspeaker system
is presenting to users. (Typically, the level
value would actually be in dBC, the Cweighted 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 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 station-originated
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
10. 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 digital
and analog 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
Figure 10. Incoming Dialnorm Level Match “Dot”
Model 76DBA/77B User Guide
Studio Technologies, Inc.
Issue 1, November 2010
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(– – – –). This could be due to a problem
with the metadata signal connected to the
Model 76DBA 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 metadataassociated 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
the letters POP will appear in the 4-digit
display whenever a channel is actively
being soloed in the channel pop solo
mode. This ensures that a user will understand that the post-fader surround digital
and analog monitor outputs no longer
represent the true inter-channel 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.
Remote Control Inputs
As previously discussed in the Installation
section of this user guide, three remote
control signals can be connected to the
Model 76DBA and then configured for operation. The functions are remote mute all,
remote dim, and remote auxiliary stereo
monitor output on/off. When an external
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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 stereo monitor outputs the
LED associated with the auxiliary stereo
monitor output enable button will flash.
If the auxiliary stereo monitor output was
already active when remote auxiliary
stereo 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 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 digital and analog
monitor output levels. A status LED lights
steadily whenever normal Model 71 operation is taking place.
Any changes made using the Model 71’s
rotary level control and buttons will be
reflected in the appropriate LEDs and displays on all the 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.
Model 76DBA/77B User Guide
Studio Technologies, Inc.
for Surround
Rotary Level Control
The rotary level control is used to manually
adjust the post-fader surround digital and
analog monitor output levels. 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 digital and analog monitor output
levels 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 digital and analog monitor
output levels to their preset values. The
operating characteristics are identical to
those of the Model 77B Control Console,
discussed earlier in this section.
Technical Notes
Loss of Sync
The Model 76DBA relies on an external
timing reference (sync) source for proper
operation. This can be in the form of an
AES3id, word clock, DARS (AES11),
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 76DBA’s back
panel. Alternately, a configuration choice
allows the L/R input of the AES3id source
currently selected for monitoring to also
serve as the system’s timing reference.
Whenever a valid sync signal has been
connected to the Model 76DBA the sync
status LED, located on the unit’s front
panel, will light. The sample rate of the
Model 76DBA/77B User Guide
Studio Technologies, Inc.
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 are provided. On
the Model 76DBA 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 Model
76DBA’s 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 digital 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 76DBA’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 that a valid sync signal is not
connected to the Model 76DBA the digital
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. The analog monitor
outputs will move to their minimum output
condition. As soon as a valid sync signal is
again connected to the Model 76DBA the
digital monitor outputs will automatically
switch to their correct sample rate and
audio signals will again be present. The
analog monitor outputs will return to their
normal signal levels.
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Power Down
Great care was taken in the Model 76DBA’s
design to minimize the chance that clicks,
pops, or other objectionable audio signals
will be present on the digital and analog
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 digital monitor outputs will switch to
silence (audio “black”) in preparation for a
complete loss of signal. Electromechanical
relays associated with the analog monitor
outputs will change to their mute state to
minimize the change of signal transients
reaching the connected inputs.
Power-Up Messages and Error
Codes
Upon mains power being applied to the
Model 76DBA 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 76DBA software
versions:
1. Displays 77B
2. Displays Model 77B’s software version
3. Displays Model 77B’s unit address
(A1, A2, A3, or A4)
4. Displays 76db
5. Displays Model 76DBA’s main software
version
6. Displays FPgA
7. Displays Model 76DBA’s logic device
(FPGA) software version
Issue 1, November 2010
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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 76DBA. The most likely cause
would be incorrect wiring of the data pair
linking the two units. Err2 indicates that the
Model 76DBA is having problems with its
internal logic device. (A high-speed fieldprogrammable gate array (FPGA) serves
as the digital “heart” of the Model 76DBA
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 it would accomplish anything.) If
the error code continues to be displayed
the Model 76DBA 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 Conversion
(SRC)
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
76DBA’s internal timing. 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 provide “singlechip” SRC solutions and an excellent one
from AKM was selected for the Model
76DBA. The technical capabilities of the
Model 76DBA’s SRC function is stated in
Model 76DBA/77B User Guide
Studio Technologies, Inc.
for Surround
this way: the sample rate of an input signal
can range from 1/6 to six times the Model
76DBA’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 76DBA’s output sample rate
is determined by the selected 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 76DBA’s output sample rate. If a
video sync signal is connected, the Model
76DBA’s sample rate is selected as part
of the configuration process.
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 76DBA’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.
As useful as allowing one disparate
sample rate to be converted to another, it
may be the ability of the Model 76DBA’s
SRC function to re-synchronize a signal
that proves most valuable. For example,
in typical post-production and broadcast
applications all signals will have a sample
rate of 48 kHz. A Model 76DBA and all of
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 76DBA’s rate, thus allowing
it to be monitored over a loudspeaker
Model 76DBA/77B User Guide
Studio Technologies, Inc.
system. In addition, the stereo input C
direct digital 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 digital monitor output
to the input of a signal router, allowing an
entire facility to access the signal.
Model 76DBA to Control
Console Connections
Figure 7 gives a detailed description of
the signals that connect the Model 76DBA
Central Controller to the one or more
Model 77B or Model 71 Control Consoles.
The Model 76DBA 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 76DBA’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 76DBA 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 76DBA Central Controller will mute
the internal digital audio channels as well
Issue 1, November 2010
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as save the current operating parameters.
No clicks, pops, or other noises will occur
when the Model 77B or Model 71 units
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 digital monitor output channel data are actively controlled by the Model 76DBA’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
a valid timing reference (sync) source is
recognized by the system the Validity bits
will be set to 1.
The Model 76DBA’s hardware is capable
of routing the C/U/V bit information from
any of the L/R inputs, as well as 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.
Issue 1, November 2010
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Model 76DBA/77B User Guide
Studio Technologies, Inc.
for Surround
Specifications
Model 76DBA Central Controller
General Audio:
Supported Sample Rates: 32, 44.1, 48, 88.2, 96,
176.4, and 192 kHz
Maximum Level: +24 dBu into 2000 (2 k) ohms or
greater
Frequency Response, Digital Inputs to Analog
Monitor Outputs: 10 Hz-20 kHz +0.0/–0.3 dB @
48 kHz sample rate; –3 dB @ 64 kHz
Distortion (THD+N): 0.004%, ref 1 kHz, +4 dBu
output
Word Length: 24 bits maximum
S/N Ratio: 89 dB, ref +4 dBu output
Internal Processing: 32 bits
Dynamic Range: greater than 109 dB
Input-to-Output Latency: one sample (e.g., 0.021
milliseconds @ 48 kHz sample rate)
Crosstalk: 98 dB at 1 kHz; 97 dB at 16 kHz,
ref –1 dBFS input
Digital Audio Inputs: 5 (18 audio channels)
Configuration: two surround (5.1) and three stereo
Connector: 25-pin D-subminiature female (DB-25F)
Type: AES3id-2001/SMPTE 276M (unbalanced
75 ohms/1 Vpp)
Connectors: BNC (per IEC 60169-8 Amendment 2)
Sample Rate Conversion (SRC):
Application: available on Stereo Input C
Input Sample Rate Range: 8 to 216 kHz, limited
to 1/6 to 6 times the output sample rate
Latency: 1 millisecond, nominal
Sync Source: configured to follow L/R of currently
selected input or signal connected to sync input
Sync Input:
Compatible Sources: word clock, DARS (AES11),
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: 16 (8 pairs)
Configuration: organized as two surround (5.1),
one auxiliary stereo, and one stereo input C direct
Dynamic Range: 135 dB
Type: AES3 (110 ohms/5 Vpp) or AES3id/SMPTE
276M (75 ohms/1 Vpp), selectable
Connector: 25-pin D-subminiature female (DB-25F)
Analog Monitor Outputs: 8
Configuration: organized as one surround (5.1)
and one auxiliary stereo
Type: electronically balanced, source impedance
200 ohms
Nominal Level: +4.0 dBu @ –20 dBFS input source
and level control at maximum setting
Model 76DBA/77B User Guide
Studio Technologies, Inc.
Configurable Delay: 0 to 340 milliseconds @
48 kHz sample rate (scales up or down depending
on actual sample rate)
Downmix:
Functions: 5.1 to stereo, stereo to mono
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
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)
Control Console Interface:
Type: RS-485, 115.2 Kbit/s, 8-1-N
Polling Interval: 50 milliseconds
Power: 12 volts DC, 500 milliamperes maximum
Connector: 9-pin D-subminiature female (DE-9F)
Dolby E Metadata Input:
Type: RS-485/RS-422
Data Rate/Format: 115.2 Kbit/s, 8-N-1
Connector: 9-pin D-subminiature female (DE-9F),
shared with remote control inputs
Remote Control Inputs: 3
Functions: remote mute all, remote dim, remote
auxiliary stereo monitor output on/off
Type: +5 V logic, activates on closure to system
common
Connector: 9-pin D-subminiature female (DE-9F),
shared with metadata input
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AC Mains:
Requirement: 100 to 230 V, +10/-15%, 50/60 Hz,
15 W maximum
Connector: 3-blade, IEC 320 C14-compatible
(mates with IEC 320 C13)
Dimensions:
19.00 inches wide (48.3 cm)
1.72 inches high (4.4 cm)
7.00 inches deep (17.8 cm)
Mounting: one space (1U) in a standard 19-inch
rack
Weight: 6.2 pounds (2.8 kg)
Model 77B Control Console
Application: up to four Model 77B Control Consoles can be connected to a Model 76DBA Central
Controller
Power: 12 volts DC nominal (9 volts DC minimum),
maximum current 100 milliamperes, provided by
Model 76DBA Central Controller
Model 71 Control Console
Application: up to three Model 71 Control Consoles can be connected to a Model 76DBA Central
Controller
Power: 12 volts DC nominal (9 volts DC minimum),
maximum current 35 milliamperes, provided by
Model 76DBA Central Controller
Control Data:
Type: RS-485
Data Rate/Format: 115.2 Kbit/s, 8-N-1
Connector: 9-pin D-subminiature female (DE-9F)
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.
Control Data:
Type: RS-485
Data Rate/Format: 115.2 Kbit/s, 8-N-1
Connector: 9-pin D-subminiature female (DE-9F)
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)
Issue 1, November 2010
Page 50
Model 76DBA/77B User Guide
Studio Technologies, Inc.
for Surround
Appendix A—Connection Pin-Out
Charts
Connections
TASCAM® Signal
Channel High (+)
Signal
Low (–)
Pin
Direction
Shield
Signal
Data + (RS-485/RS-422)
7
Input
Pre-Fader L/R
1
24
12
25
Data – (RS-485/RS-422)
2
Input
Pre-Fader C/LFE
2
10
23
11
Data Shield
1
Shield
Pre-Fader LS/RS
3
21
9
22
Remote Mute All
5
Input
Stereo Input C Direct
4
7
20
8
Remote Dim
6
Input
Post-Fader L/R
5
18
6
19
Remote Aux Stereo Monitor Out On/Off
8
Input
Post-Fader C/LFE
6
4
17
5
Remote Spare
9
Input
Post-Fader LS/RS
7
15
3
16
Remote Common
4
Common
Auxiliary Stereo
8
1
14
2
Note: Connector type on Model 76DBA is 9-pin D-subminiature
female (DE-9F) Connector uses 4-40 threaded inserts
for locking with mating plug.
Notes: 1) All signals transformer-coupled digital audio;
selectable for AES3 or AES3id compatibility.
2) Connector type on Model 76DBA 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.
Connections for Metadata and Remote Control
Inputs
3) Wiring scheme follows TASCAM DA-88 convention.
Standard DA-88-type wiring harnesses are directly
compatible, with the possible exception of 4-40 screw
threads being required.
Connections for Digital Monitor Outputs
Signal
High (+)
Signal
Low (–)
Shield
Surround L
24
12
Surround R
10
Surround C
Surround LFE
Connections
Signal
Pin
Direction
Data + (RS-485)
1
To/From Models 77B/71
25
Data – (RS-485)
6
To/From Models 77B/71
23
11
Data Shield
2
To/From Models 77B/71
21
9
22
DC + (12 V)
4
To Models 77B/71
7
20
8
DC – (12 V Return)
9
To Models 77B/71
DC Power Shield
5
To/From Models 77B/71
Surround LS
18
6
19
Surround RS
4
17
5
Auxiliary Stereo L
15
3
16
Auxiliary Stereo R
1
14
2
Notes: 1) Connector type on Model 76DBA 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 76DBA is 9-pin D-subminiature
female (DE-9F). Connector uses 4-40 threaded inserts
for locking with mating plug.
Connections between Model 76DBA and
Model 77B and Model 71
2) 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 Analog Monitor Outputs
Model 76DBA/77B User Guide
Studio Technologies, Inc.
Issue 1, November 2010
Page 51
for Surround
Appendix B—Sync Input Sources
The Model 76DBA’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.
Bi-Level and Tri-Level Video: See table below.
Video Format
Video Format, continued
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
Issue 1, November 2010
Page 52
Model 76DBA/77B User Guide
Studio Technologies, Inc.
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