76DB/77B User Guide_4
for Surround
Model 76DB Central Controller and
Model 77B Control Console
User Guide
Issue 4, November 2010
This User Guide is applicable for systems consisting of:
Model 76DB: serial number M76DB-00201 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
50232-1110, Issue 4
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for Surround
Table of Contents
Introduction ................................................................... 5
Installation .................................................................... 9
Configuration ................................................................17
Operation ......................................................................35
Technical Notes ............................................................43
Specifications ...............................................................47
Appendix A—Connection Pin-Out Charts ....................49
Appendix B—Sync Sources .........................................50
Model 76DB/77B User Guide
Studio Technologies, Inc.
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Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
Introduction
What This User Guide Covers
This User Guide is designed to assist
you when installing and using the Model
76DB Central Controller and one or more
associated Model 77B or Model 71 Control
Consoles.
Overview
As creating and distributing multi-channel
surround (5.1) and stereo 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
an “all-digital” world now upon us, additional
monitoring challenges have arisen. Studio
Technologies has addressed these needs
with the StudioComm for Surround Model
76DB Central Controller and the Model 77B
and Model 71 Control Consoles. With the
digital audio inputs and outputs, Dolby® E
dialnorm support, and extensive set of
user resources it’s a simple task to integrate
a monitoring system into virtually any facility. The carefully selected group of features,
including flexible input source selection,
multiple outputs, dialnorm display, channel
downmix, and multiple-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 unique needs
of broadcast master control applications.
An all-digital StudioComm for Surround
system starts with the Model 77B Control
Console. It’s the system’s “command center”
and is designed to reside at an operator’s
location, allowing fingertip selection of all
Model 76DB/77B User Guide
Studio Technologies, Inc.
monitoring functions. Numerous LED
indicators provide complete status information. A 4-digit numeric display indicates
the monitor output or dialnorm level in real
time. A major strength of the Model 77B is
its ability to configure, under software control, many important operating parameters.
The Model 71 Control Console is a compact user control surface that is intended
for secondary monitoring locations. It provides three of the most basic functions: a
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 76DB provides power for all connected Model 77B
or Model 71 units.
The heart of this StudioComm system is
the Model 76DB Central Controller. The
one-rack-space unit contains audio input,
output, processing, and support circuitry.
The Model 76DB provides two surround
(5.1) and three stereo audio inputs. These
unbalanced digital inputs are AES3id/
SMPTE 276M-compliant. Sources of this
type are ubiquitous in most post-production and broadcast environments. A sample rate of up to 192 kHz with a bit depth
of up to 24 are directly supported. Circuitry
associated with one of the stereo inputs
provides sample rate conversion (SRC)
capability, allowing a wide range of digital
audio sources to be monitored. Up to 340
milliseconds of input delay can be selected
to compensate for processing delays in an
associated video path. For synchronization
with a master timing reference a dedicated
source of word clock, DARS (AES11),
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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.
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.
Two surround (5.1) and two stereo monitor
outputs are provided. The post-fader surround monitor output is intended for connection to a monitor loudspeaker system.
The pre-fader surround monitor output can
be used with metering systems that require
signals that aren’t impacted by level control
or other monitoring functions. The auxiliary
stereo monitor output is provided for special
broadcast applications where an independent output with separate on/off control is
desired. The stereo input C direct monitor
output allows an installation to directly
access the SRC capabilities.
A source of Dolby E metadata can be
connected to the Model 76DB Central
Controller. This RS-485/RS-422 115.2 kbit/s
serial data signal carries numerous data
elements, including one that represents
the average dialog level of an associated
audio program. This dialog normalization
or “dialnorm” value is an integral part of
many broadcast distribution systems,
ending up as part of consumer audio
playback systems. Hardware and software
within the Model 76DB separates the
dialnorm element that relates to one of the
connected surround audio sources. This
dialnorm level value can be displayed on
the Model 77B Control Console, as well
as being used to automatically adjust the
post-fader surround monitor output level.
This provides a unique solution for the
For installation flexibility the outputs can be
configured for compatibility with equipment
that requires AES3 (“balanced”) or AES3id
(“unbalanced”) digital audio signals. When
selected for AES3 compatibility the output
Figure 1. Model 76DB Central Controller Front Panel
Control console
status LED
Metadata
status
LED
Sync
status
LED
Figure 2. Model 76DB Central Controller Back Panel
AC mains
input connection
To/from
Models 77B &
71 Control
Consoles
RS-485 and
remote control
inputs
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Digital
monitor
output
connections
Sync
Input
connection
Surround Input B
connections
Stereo
Input C
connection
Stereo Input A and
Stereo Input B
connections
Surround Input A
connections
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for Surround
Channel solo
Auxiliary stereo
monitor output
enable
Downmix
Display mode
Dialnorm and
monitor output
level display
Input select
Post-fader surround
monitor output
• Dialnorm enable
• Reference level
• Mute all
• Dim
• Rotary level control
Figure 3. Model 77B Control Console Front Panel
broadcast and post-production world,
allowing a professional environment to accurately simulate an end user’s experience.
76DB. AC mains power is connected
directly to the Model 76DB, with an acceptable range of 100 to 230 volts, 50/60 Hz.
Great care was taken when designing the
system’s architecture, ensuring that the
character of the audio input signals is preserved. All audio processing is performed
in 32-bit words using a high-speed fieldprogrammable gate array (FPGA) integrated circuit.
Additional Details
The Model 76DB occupies one space (1U)
in a standard 19-inch rack. Digital audio signals are interfaced with the Model 76DB’s
inputs using nine BNC connectors. A tenth
BNC connector is used by the sync source.
Monitor output signal connections are made
using one 25-pin D-subminiature connector. One 9-pin D-subminiature connector is
used to connect the Model 76DB with up to
four Model 77B or Model 71 Control Consoles. A second 9-pin “D-sub” connector
is used to interface Dolby E dialnorm data
and remote control signals with the Model
Model 76DB/77B User Guide
Studio Technologies, Inc.
The Model 77B provides four buttons and
associated LEDs for selecting the input
source to be monitored. The buttons are
designed such that up to six unique input
choices are available. Using the Model
77B’s configuration mode, each of the six
input choices can be configured from the
system’s two surround (5.1) and three
stereo inputs. The configuration mode also
allows stereo inputs A and B to be used as
either stereo or monaural sources. This is
especially useful in broadcast applications
where a 2-channel AES3id source may
carry two independent monaural signals.
To highlight this powerful feature: the
Model 77B allows independent monitoring of the two channels associated with a
single AES3id source. Broadcast master
control applications can greatly benefit
from this configuration flexibility.
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The post-fader surround monitor output
level can be controlled by way of a large,
easy-to-use rotary control. The control,
actually a digital encoder, allows level
selection in precise 0.5-dB steps. The
auto mute all function causes the postfader surround monitor output channels
to automatically mute whenever the output
level control reaches maximum attenuation. Using the reference level function, the
post-fader surround monitor output level
can be set to a pre-configured value. This
is provided for audio-with-picture applications that require a specific monitor output
level. The reference level is easily configured by taking an electronic “snapshot” of
the desired monitor output level. For operator confirmation a 4-digit LED readout can
display the level of the post-fader surround
monitor output channels. To match the
needs of a facility, it can be configured to
display either the attenuation level or the
sound pressure level (SPL).
The dim function allows the post-fader
surround monitor output level to be
reduced by a fixed dB amount. The dim
level is configured from among four available values. A mute all function allows
the post-fader surround monitor output
channels to be simultaneously muted. The
channel solo section provides post-fader
surround channel monitoring control, allowing a single channel to be monitored
while the others are automatically muted.
Multiple channels can also be simultaneously selected for “soloing.”
A special solo mode is also provided,
called channel pop solo, which offers a
unique aid in monitoring audio material.
Channel pop solo allows the level of a
single channel to be raised while the level
of the other channel is reduced. This helps
to emphasize the content on one channel
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without fully muting the others. Broadcast
applications can benefit from the channel
pop solo mode 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 monitor
outputs. A configuration setting allows the
pre-fader surround monitor outputs to be
selected for pre- or post-downmix operation.
In addition to the surround (5.1) monitor
output, a auxiliary stereo monitor output is
also provided. A stereo signal, connected to
stereo input C on the Model 76DB Central
Controller, can be routed to the auxiliary
output. A pushbutton on the Model 77B
Control Console allows on/off control of the
signal; no level control or signal modification
takes place. The auxiliary output feature can
be useful in special applications, e.g., in a
broadcast control room setting where an
audio signal, such as site-event cue signals,
needs to be monitored by way of an independent set of loudspeakers.
For flexibility, the StudioComm for Surround
system is designed to easily integrate with
equipment such as production intercom
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Studio Technologies, Inc.
for Surround
systems, on-air or recording tally signals, or
audio consoles. Three remote-control inputs
provide access to the mute all, dim, and
auxiliary 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 monitor
output or enable the auxiliary output.
Installation
In this section you will be installing the
Model 76DB Central Controller in an equipment rack. Connections to the audio inputs
and monitor outputs will be made. A dedicated digital 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 76DB. AC mains power
will be connected to the Model 76DB. For
advanced applications up to three additional Model 77B or Model 71 Control Console
units can be connected to the Model 76DB.
System Components
The main shipping carton contains one
each of the following: Model 76DB Central
Controller, Model 77B Control Console,
9-pin D-sub interconnecting cable, and
user guide. Also included in the shipping
carton is a North American-standard AC
mains cord. Your dealer or distributor should
provide an AC mains cord for destinations
outside of North America. Any additional
Model 77B or Model 71 Control Consoles
will be shipped in separate cartons.
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Mounting the Model 76DB
The Model 76DB Central Controller
requires one space (1U) in a standard
19-inch (48.3 cm) equipment rack. Secure
the Model 76DB 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 76DB to the
Model 77B. If the needs of a specific installation dictate, an alternate-length interconnecting cable can be fabricated and used.
Audio Connections
Audio connections are made by way of
nine BNC jacks and a 25-pin D-subminiature connector. All the connectors are
located on the Model 76DB’s back panel.
Refer to Figure 2 for a detailed view of
these jacks and connector.
Audio Inputs
Prior to digital audio sources being connected to the five inputs it’s worth reviewing how they are used by the StudioComm
system. Surround inputs A and B each
have six channels (5.1) and can be configured for monitoring over the pre- and postfader surround monitor output channels.
A one-to-one 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 the 5.1 to stereo downmix function.)
Stereo inputs A and B can be configured
to be used as a stereo source or as two
independent monaural sources. When
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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 digital audio source can supply one
or two monaural signals to the StudioComm
system and be correctly monitored.
Stereo input C can serve as a source for
the pre- and post-fader surround monitor
outputs. As with the other inputs, stereo
input C can be assigned, using the configuration function, to an input select button.
This will allow stereo input C to be monitored using the left and right channels of
the surround monitor outputs.
In addition, the signal connected to stereo
input C will be routed to the auxiliary stereo
monitor output whenever that function is active. To clarify: if the auxiliary stereo monitor
output is enabled a signal on the left channel of stereo input C will be present on the
left channel of the auxiliary stereo monitor
output; a signal on the right channel of stereo input C will be present on the auxiliary
stereo monitor output’s right channel.
Stereo input C is also routed to the stereo
input C direct monitor output. A one-to-one
channel mapping scheme is maintained.
The signal present on the stereo input C
direct monitor output is post (after) the
sample rate conversion (SRC) and input
delay functions but pre (before) the downmix, level control, and on/off functions.
It’s important to note that there is one
limitation regarding stereo input C. Unlike
stereo inputs A and B, it can only be used
as a stereo source. Its left and right channels can’t be independently monitored over
the center channel of the surround monitor
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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 monitor output. It follows a left-in-to-left-out, right-in-to-right-out
scheme.
The inputs support digital audio signals
with sampling a 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 76DB’s all-digital signal path.
There is, however, an exception worth
noting. Circuitry associated with stereo
input C has sample rate conversion (SRC)
capability, allowing virtually any digital
audio signal to be connected. 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.
Nine BNC jacks on the Model 76DB’s
back panel are used to interface with the
18 channels associated with the digital
audio signal sources; each BNC connector carries two audio channels. The digital
audio inputs are intended for connection
to unbalanced digital audio sources that
are compatible with the AES3id standard.
In broadcast environments these signals
may also be referred to as following the
SMPTE 276M standard. This signal type
has a nominal impedance of 75 ohms and
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.
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for Surround
Balanced AES3 digital audio signals
can also be used with the Model 76DB’s
inputs if external coupling transformers
(“baluns”) are utilized. These impedancematching (110 ohms to 75 ohms) and
level-attenuating transformer assemblies
typically provide a 3-pin female XLR connector on their input and a female BNC
connector on their output.
Monitor Outputs
The 25-pin D-subminiature connector
labeled Digital Monitor Outputs provides
access to the Model 76DB’s 16 channels of digital audio: pre-fader surround,
post-fader surround, auxiliary stereo, and
stereo input C direct monitor output. The
pre-fader surround monitor output channels are intended for connection to metering or monitoring equipment that requires
uninterrupted full-level signals. The postfader surround monitor output channels
are intended to connect to the main 5.1
loudspeaker system. The auxiliary stereo
monitor output is provided to support a
separate set of loudspeakers, the primary
application intended to allow monitoring
of inter- or intra-facility communications.
The stereo input C direct monitor output is
essentially a unity gain copy of the signal
connected to stereo input C. However, the
signal does pass through the sample rate
conversion (SRC) and input delay circuitry.
The impact made by these functions will
depend on the specific input signal and the
Model 76DB’s configuration settings.
It’s important to reiterate that all the monitor outputs are digital; the Model 76DB
doesn’t provide any analog outputs! This
requires that all equipment connected to
the Model 76DB’s monitor outputs provide
digital input capability.
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For flexibility the monitor outputs are transformer-coupled and can be configured to
act as AES3 or AES3id digital audio sources. The monitor outputs are configured in
two groups with separate choices available
for the pre-fader surround/stereo input C
direct group and post-fader surround/
auxiliary stereo monitor output group.
When a group is set for AES3 (110 ohms/
5 Vpp) the signals are compatible with
AES3 interfaces. Signals of this type are
normally interconnected using shielded
twisted-pair cable and 3-pin XLR connectors. When a group is configured for
AES3id (75 ohms/1 Vpp) the source impedance and signal level are compatible
with the requirements of AES3id interfacing. These signals are typically interconnected using coaxial cable terminated
with BNC connectors. For details on how
a Model 77B is used to select the digital
monitor output types refer to the Configuration section of this user guide.
A cable assembly with a 25-pin D-sub plug
(male) on one end and the desired connectors on the other end will be used for
connecting to the digital monitor outputs.
The D-subminiature connector follows the
TASCAM® wiring convention, organizing
the 25 pins into eight groups of three pins
each; one pin remains unused. Each set of
three pins provides an independent interface. In the analog world this would allow
eight audio signals to be transported. But
with AES3/AES3id digital audio signals
this allows support for 16 audio channels;
eight interfaces each supplying two audio
channels.
A wiring assembly prepared for the Model
76DB’s monitor outputs, when configured
for AES3 (110 ohms/5 Vpp), would be
identical to that of a DA-88-style output
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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
76DB’s digital monitor outputs, when set
for AES3id (75 ohms/1 Vpp), would
typically have eight BNC plugs attached.
For compatibility with AES3 balanced
digital audio signals connect the D-sub’s
+ terminal as signal high and the – terminal as signal low. In most applications a
3-pin XLR plug (male) will be used. In this
case the + terminal would go to pin 2 of
the XLR, the – terminal to XLR pin 3, and
the shield terminal to XLR pin 1.
For compatibility with AES3id unbalanced
digital audio signals connect the D-sub’s
+ terminal as signal high, and both the
– and shield terminals as the signal low/
shield. When terminating to a BNC plug
the D-sub’s + terminal should connect to
the center pin; the – and the shield connections should go to the “body” of the
BNC plug. To clarify, for optimal operation,
it is best to connect both the – and shield
together directly on the D-sub plug, rather
than at the BNC end of the interface assembly. Note that the output circuitry is
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
76DB’s D-sub connector use 4-40 threads.
This complies with the original design
standard for D-subminiature connectors.
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Connections
TASCAM® Signal
Channel High (+)
Signal
Low (–)
Shield
Pre-Fader L/R
1
24
12
25
Pre-Fader C/LFE
2
10
23
11
Pre-Fader LS/RS
3
21
9
22
Stereo Input C Direct
4
7
20
8
Post-Fader L/R
5
18
6
19
Post-Fader C/LFE
6
4
17
5
Post-Fader LS/RS
7
15
3
16
Auxiliary Stereo
8
1
14
2
Notes: 1) All signals transformer-coupled digital audio;
selectable for AES3 or AES3id compatibility.
2) Connector type on Model 76DB is 25-pin
D-subminiature female (DB-25F). Installer must
provide male (DB-25M). Connector uses 4-40
threaded inserts for locking with mating plug.
3) Wiring scheme follows TASCAM DA-88 convention.
Standard DA-88-type wiring harnesses are directly
compatible, with the possible exception of 4-40 screw
threads being required.
Figure 4. Connections for Monitor Outputs
Pre-Fader Surround Monitor Outputs
The pre-fader surround monitor output
channels are intended to connect to
metering, measurement, test, or other
signal monitoring equipment that require
uninterrupted, full-level digital audio signal
sources.
Stereo Input C Direct Monitor Output
The stereo input C direct monitor output
is intended for use in site-specific applications. It provides an uninterrupted, full-level
digital audio “copy” of the signal source.
Post-Fader Surround Monitor Outputs
The post-fader surround monitor output
channels are designed for connection to
audio amplifiers associated with monitor loudspeakers or to the inputs of loudspeakers that contain integrated amplifiers.
Auxiliary Stereo Monitor Output
The auxiliary stereo monitor output is intended to connect to an amplifier
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for Surround
associated with a set of loudspeakers or
an amplified-speaker. In either case a user
level control must be provided.
Sync Input
The Model 76DB requires a timing reference (sync) signal so that the digital audio input and output signals will function
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 dedicated timing reference signal to the Model 76DB’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 are
typically provided to support NTSC or PAL
broadcast applications, although they’re
also used by some later-generation equipment. Tri-level sync signals are primarily associated with facilities that support
high-definition (HD) video equipment. Both
bi-level and tri-level signals can be found
at numerous rate combinations, configured
to allow for compatibility with the various
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Studio Technologies, Inc.
video formats. With all of these sync
source choices available proper Model
76DB operation should be easy to obtain.
Extensive testing has been done using
many different sync source types and
rates. Interested users can refer to Appendix B of this user guide for details.
The external sync reference source should
be connected to the sync input BNC connector located on the Model 76DB’s back
panel. For flexibility the input can be configured to be high-impedance (“floating”) or
terminated with an impedance of 75 ohms.
A sync source that is dedicated for use by
the Model 76DB’s sync input will typically
have input termination enabled. If the sync
signal connected to the Model 76DB is being connected (“multed”) to other inputs it
may be desirable for the termination to be
disabled. A general “rule of thumb” is that
termination should be applied only at the
location of the last physical device using a
sync signal.
Metadata Input
The Model 76DB allows a source of
Dolby E metadata to be directly connected.
Hardware and software inside the Model
76DB extracts (“parses”) one of the dialnorm data elements from the connected
metadata signal. This dialnorm value can
be viewed on the Model 77B’s LED display
and, if desired, used to control the level
of the post-fader surround monitor output
channels. Refer to the Technical Notes
section of this guide for details.
The metadata signal is connected by
way of a 9-pin D-subminiature connector,
labeled RS-485/Remote Control Inputs,
which is located on the back panel of
the Model 76DB. Refer to Figure 5 or
Appendix A for exact connection details.
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Signal
Pin
Direction
Data + (RS-485/RS-422)
7
Input
Data – (RS-485/RS-422)
2
Input
Data Shield
1
Shield
Remote Mute All
5
Input
Remote Dim
6
Input
Remote Aux Stereo Monitor Out On/Off
8
Input
Remote Spare
9
Input
Remote Common
4
Common
Note: Connector type on Model 76DB is 9-pin D-subminiature
female (DE-9F) Connector uses 4-40 threaded inserts
for locking with mating plug.
Figure 5. Connections for Metadata and Remote
Control Inputs
While only the data + and data – connections are absolutely necessary, a shield
connection can also be made. Note that
the connections for the metadata signal are
reminiscent of the SMPTE 207M standard.
The metadata signal must be in the form
of RS-485 or RS-422 asynchronous serial
data. This differential signal must have a
data rate of 115.2 kbit/s and a data format
of 8 data bits, no parity, and 1 stop bit
(8-N-1). A metadata signal of this type
is commonly available on metadatagenerating or de-embedding equipment
from broadcast equipment manufacturers
such as Dolby Laboratories®, Evertz®,
and Miranda®.
While in hardware the Model 76DB’s
RS-485 input connection is bi-directional,
in software it’s configured only to receive
data. The input impedance is 2200 ohms,
almost 20 times the nominal value for
RS-485. This means that there’s no reason
why a signal already connected between
two other pieces of equipment can’t also
be connected in parallel (“bridged”) with
the Model 76DB’s metadata input.
Issue 4, November 2010
Page 14
A word of advice—Studio Technologies
has found documentation supplied with
some metadata-generating equipment
has incorrect (or at least confusing) pinout information. This has resulted in much
head scratching and hair pulling. As such,
it may be valuable to use a logic analyzer
or oscilloscope to confirm that the metadata source is on the expected pins of the
source connector prior to connecting it to
the Model 76DB.
Remote Control Inputs
Support is provided for three remote
control input functions: remote mute all,
remote dim, and remote auxiliary stereo
monitor output on/off. The Model 76DB’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 overcurrent and static (ESD) discharge, care
should be taken to prevent nasty signals
from reaching them. The inputs are active
only when held in the low state; they can’t
be configured to change state (“latch”) in
response to a logic pulse.
The same 9-pin D-subminiature connector
used for the metadata input is also used
for the remote control inputs. Refer to
Figure 5 or Appendix A for the exact connection details. Note that pin 4 (remote
common) connects to the Model 76DB’s
internal circuit common connection as well
as to the Model 76DB’s chassis and mains
earth connections. Figure 5 also shows
one spare remote control input (pin 9).
This is provided for future applications
and should remain unconnected.
Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
Connecting the Model 76DB
to the Model 77B
A 9-pin female D-subminiature connector, labeled To/From Control Consoles, is
provided on the back panel of the Model
76DB Central Controller. This is used to
interface the unit with Model 77B Control
Consoles. Refer to Figure 6 or Appendix A
for details. A 9-pin female D-sub connector, labeled To/From Central Controller, is
provided on the back panel of each Model
77B Control Console. A cable with 9-pin
male D-sub (DE-9M) connectors on each
end is used to interconnect the Model
76DB with a Model 77B unit. A cable is
included in the shipping carton. The cable
implements all nine connector pins in a
one-to-one manner.
Should an interconnecting cable of a
different length be required there’s no
problem for one to be fabricated and used.
While it can be wired in a one-to-one
fashion supporting all nine pins, only four
connections are required: pin 1 (data +),
pin 6 (data –), pin 4 (DC +), and pin 9
(DC –). The Model 76DB’s connector pinout scheme was designed to allow creation
of an interconnecting cable which uses
commonly available 2-pair audio cable.
This cable, consisting of two twisted pairs
each with an individual shield, is typically
sleek, flexible, and available in many colors. One pair and shield can be used for
the data connections while the other pair
and shield can be used for the DC connections. This implementation has the advantages of providing a shield for the data
path and a more robust common connection (two conductors including the shield)
for the DC power circuit.
Model 76DB/77B User Guide
Studio Technologies, Inc.
Signal
Pin
Direction
Data + (RS-485)
1
To/From Models 77B/71
Data – (RS-485)
6
To/From Models 77B/71
Data Shield
2
To/From Models 77B/71
DC + (12 V)
4
To Models 77B/71
DC – (12 V Return)
9
To Models 77B/71
DC Power Shield
5
To/From Models 77B/71
Note: Connector type on Model 76DB is 9-pin D-subminiature
female (DE-9F). Connector uses 4-40 threaded inserts
for locking with mating plug.
Figure 6. Connections between Model 76DB and
Model 77B and Model 71
A few simple calculations are required to
determine the maximum cable length when
connecting a Model 76DB 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
76DB to a Model 77B. The Model 76DB
supplies 12 volt DC nominal with a maximum current of 500 milliamperes.
The Model 77B requires a minimum of
9 volts DC, 100 milliamperes, for correct
operation. (The voltage must be measured
directly at the Model 77B’s 9-pin connector.) So the maximum interconnecting
cable length is directly related to the resistive voltage losses associated with the
two DC-carrying conductors. As the Model
76DB supplies 12 volts and the Model
77B requires 9 volts minimum, this directly
leads to a 3 volt DC maximum drop due
to the interconnecting cable. Using Ohm’s
law it’s quite easy to determine whether
the selected cable will support the desired
interconnection length. Calculate the voltage drop by multiplying the total resistance
(in ohms) of the proposed cable by 0.1 (the
Model 77B’s required current in amperes).
Issue 4, November 2010
Page 15
for Surround
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 76DB’s ability to be controlled by
additional control consoles. At least one
Model 77B Control Console must be connected to the Model 76DB Central Controller. After this requirement has been met up
to three additional Model 77B or Model 71
Control Consoles can also be connected
and powered by the Model 76DB.
When connecting multiple control consoles
to a Model 76DB all nine pins of each interconnecting cable can be connected in parallel (“multed”). This will electrically mult the
data and 12 volt DC power signals between
all the units. A custom cable implementation requires just four pins to be connected:
pin 1 (data +), pin 6 (data –), pin 4 (DC +),
and pin 9 (DC –).
To make installation simple, a “bus”
cable assembly can be created using a
short length of ribbon cable with one male
and multiple female 9-pin D-subminiature
insulation-displacement connectors
attached. Then standard 9-pin cables can
link the control consoles with the connectors on the bus cable.
Refer to the previous paragraphs of this
user guide where the issues involving
Model 76DB to Model 77B cable length
are discussed. Note the 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.
Issue 4, November 2010
Page 16
AC Mains Power
The Model 76DB operates directly from
AC mains power of 100 to 230 V, 50/60 Hz.
Being a “universal input” device, there are
no switches to set or jumpers to install to
match a location’s mains voltage. The unit
uses a 3-pin IEC 320 C14 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 IEC 320
C13 socket on the other. Units bound for
other destinations require that the appropriate cord be used. The wire colors in the
mains cord must conform to the internationally recognized color code and should
be terminated accordingly:
Connection
Neutral (N)
Line (L)
Protective Earth (E)
Wire Color
Light Blue
Brown
Green/Yellow
Safety Warning: The Model 76DB
does not contain an AC mains disconnect switch. As such, the AC mains
cord plug serves as the disconnection
device. Safety considerations require
that the plug and associated outlet be
easily accessible to allow rapid disconnection of AC mains power should it
prove necessary.
As soon as mains power is applied the
Model 76DB will perform a power-up sequence. The three LEDs on the right side
of the front panel will individually light in
a rapid right-to-left test sequence. Then
the three LEDs will flash in cadence while
the firmware loads into the Model 76DB’s
main logic device. After just a few seconds
operation can commence and the three
LEDs will perform their intended functions.
Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
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 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.
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 76DB. At this point
normal system operation can begin.
All connected Model 71 units will also go
through a power-up sequence after mains
power is applied to the Model 76DB. Each
of the 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 76DB. If the Model 71’s status LED does not light check to see if there
is a device address conflict among all connected control consoles and that all cables
are connected properly.
Should an error be detected during the
start-up process the three LEDs on the
Model 76DB’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.
Model 76DB/77B User Guide
Studio Technologies, Inc.
Configuration
After the physical installation has been
completed it’s important that the system’s
configuration options be carefully reviewed.
In most cases one or more of the operating
parameters will need to be revised to meet
the needs of the specific installation. Many
of the configuration parameters will impact
the signal flow in to and out of the Model
76DB Central Controller. Other parameters
affect how the one or more Model 77B
Control Consoles will display status conditions and respond to user commands.
Most of the configuration choices will be
made using a Model 77B Control Console.
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 Stereo Monitor Output Nominal
Level
• Sync Source
• Sync Input Termination
• Audio-Synced-to-Video Sample Rate
• Monitor Output Types
• Input Select Buttons
• Reference Level
• Overall Display Mode
Issue 4, November 2010
Page 17
for Surround
• Reference Level in dB SPL
• Dialnorm Reference Level
• Dialnorm-Data-to-Surround-Input
Assignment
• Dim Level
• Remote Inputs
• Input Delay
• Channel Pop Solo Mode Offset Levels
• LFE Downmix Mode
• Pre-Fader Surround Monitor Output
Mode
Configuration diagrams, located later in
this section, give details on setting each
parameter. An overview of each configurable parameter is provided in the following
paragraphs.
Entering and Exiting the
Configuration Mode
A small button is located on the back of
each Model 77B Control Console, adjacent
to 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 76DB into
their configuration modes. Other connected Model 77B and Model 71 units will
enter a standby mode. When the Model
76DB enters its configuration mode it will
immediately mute the monitor outputs as
a speaker protection measure. When a
Model 77B enters the configuration mode
its array of buttons and LEDs no longer
perform their normal functions, instead
they are used to display the operating
parameters and reflect configuration
changes as they are made.
Issue 4, November 2010
Page 18
As a user aid, a Model 77B that has entered the configuration mode will have its
dialnorm and output level LEDs (associated with the display mode section) light
in an alternating manner. Other connected
Model 77B units will indicate that they have
entered the standby mode by simultaneously flashing their dialnorm and output
level LEDs.
To leave the configuration mode and return
the system to normal operation requires
one last action to be made on the Model
77B unit that’s in its configuration mode;
press and hold its configure button for two
seconds. Note that configuration changes
are stored in nonvolatile memory only after
the configuration mode has been exited.
Our apologies to those of you who find
the configure button a pain to use, but it’s
supposed to be that way! Seriously, the top
of the button is slightly recessed from the
back panel, making it harder to accidentally activate. We didn’t want normal operation to cease because someone pushed a
Model 77B into a “rats nest” of schedules,
memos from management, and empty coffee cups! But a firm press with the fleshy
part of an index finger should do the trick.
There is no problem frequently “tweaking” the system’s operating parameters
to achieve the desired performance. The
configuration data is stored in nonvolatile
memory, which is rated for thousands of
read and write cycles and a retention time
in tens of years. Note that memory integrated circuits are located in the Model
76DB Central Controller as well as the
Model 77B and Model 71 Control Consoles. However, only the individual device
address is stored in each Model 77B and
Model 71. All other configuration parameters are stored in the Model 76DB.
Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
Model 77B Device Address
A unique device address must be assigned
to each Model 77B that is connected to
a Model 76DB. The choices are A1, A2,
A3, or A4, with the default address being
A1. As most installations will find only one
Model 77B utilized, its default setting is
appropriate. For installations that use a
second, third, or fourth Model 77B each
unit must be configured with a unique
device address. Problems will occur if
more than one unit has the same address!
It’s important to highlight the fact that the
device address is the only setting that
must be done on each individual Model
77B unit. All other settings can be made on
any one of the connected Model 77B units.
Be sure that any selected address does
not conflict with addresses to be assigned
to Model 71 units.
Stereo Input C Sample Rate
Converter
Circuitry associated with stereo input C
can provide sample rate conversion (SRC)
of connected digital audio signals. The
acceptable input range for sample rate
conversion is very wide, but is dependent
upon the output sample rate. With an output sample rate of 48 kHz any signal with
a sample rate over a range of 8 to 216 kHz
can be properly monitored by the system.
This capability can be especially useful with a signal that is not synchronized
with respect to the others connected to
the Model 76DB, even if its sample rate is
identical. The only compromise is that the
SRC process adds a fixed input-to-output
(group) delay of approximately 1 millisecond, a value that shouldn’t impact most
installations. As such, it’s recommended
that the sample rate converter remain
Model 76DB/77B User Guide
Studio Technologies, Inc.
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
monitor output can be configured to match
the requirements of a specific installation.
Devices connected to the auxiliary stereo
monitor output could include an amplifier
associated with a loudspeaker system or
inputs on self-contained amplified loudspeakers. (These types of devices must
include a means of adjusting their output
level.) This configuration setting defines
the relative output level when an input
source is connected and the auxiliary stereo monitor output is enabled. The choices
are 0, –6, –12, or –18 dB. The 0 dB setting
will typically be correct when connecting to
the input of a device that’s not associated
with a loudspeaker system. With no gain
or loss, this setting creates a unity-gain
input-to-output relationship. Devices such
as amplified speakers will often perform
better when receiving signals with a lower
nominal level. In this case the ability to
comfortably use a level potentiometer may
be enhanced by selecting the –6, –12, or
–18 dB settings.
Sync Source
The Model 76DB 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.
Issue 4, November 2010
Page 19
for Surround
Sync Input Termination
The sync input circuitry can be configured
to terminate the signal connected to the
back-panel sync input BNC connector. When
termination is selected a 75 ohm load is
applied to the signal. When the sync input
is not terminated the input impedance is
very high, essentially applying no load to the
source. If the sync source is connected only
to the Model 76DB then enabling termination
is typically appropriate. 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 76DB’s timing reference the sample
rate of the connected digital audio signals
must be specified. In most cases the default
value of 48 kHz will be appropriate, but
rates from 32 to 192 kHz are available.
Pre-Fader Surround/Stereo
Input C Direct Monitor Output
Type
To meet the needs of specific installations
the nominal impedance and level characteristic of the pre-fader surround and stereo input C direct monitor outputs can be selected.
They are selected as a group; configuration
of individual outputs is not provided. If the
output signals are going to be connected to
balanced AES3 inputs then the setting that
provides a source impedance of 110 ohms
and a nominal 5 Vpp output level would be
appropriate. If the output signals are going
to be connected to unbalanced AES3id
inputs then the setting that provides a
75 ohm source impedance and a nominal
output level of 1 Vpp would be correct.
Issue 4, November 2010
Page 20
Post-Fader Surround/Auxiliary
Stereo Monitor Output Type
The source impedance and output level of
the post-fader surround and auxiliary stereo
monitor outputs, as a group, can be configured. The information previously provided
concerning the pre-fader surround and stereo input C direct monitor output type also
applies to these outputs.
Input Select Buttons
The three input select buttons, along with
the group select button, allow six source
configurations to be selected for monitoring. The Model 76DB has connections for
two surround (5.1) and three stereo 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 preand 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.
Reference Level
For audio-with-picture applications it’s often
beneficial for monitoring to be done in reference to a known loudspeaker level. This
is often referred to as “mixing to 85 dB”
on the monitors. The StudioComm for
Surround system allows a precise postfader surround monitor output level to be
Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
stored, and then enabled by pressing the
Model 77B button labeled Reference Level.
Setting the reference level is very simple
but care is required:
1. Set up a precision sound pressure level
(SPL) measuring device at the desired
listening location.
2. Place the StudioComm system in the
normal operating mode, not the configuration mode. Be certain that the
dim, mute all, reference level, dialnorm
enable, and downmix functions are not
active. The remote mute all and remote
dim functions must also not be active.
3. Use the Model 77B Control Console
to select the input source that contains
the desired reference signal source,
e.g., pink noise.
4. Observing the SPL meter, adjust the
Model 77B’s rotary level control until the
desired loudspeaker system reference
level has been reached.
5. Being careful not to disturb the position
of the rotary level control, enter the configuration mode by pressing and holding
the configuration button located on the
Model 77B’s back panel.
6. Once the configuration mode has been
entered, all the monitor outputs will
mute. Press and hold the reference level
button; its associated LED will begin to
flash. After five seconds the LED will
light steadily to indicate that a “snapshot” of the new reference level has
been taken. The Model 77B’s numeric
display will then show the value of the
new reference level. The value shown
will always be a negative number as it’s
always a value less than the maximum
output level. The reference level button
can now be released.
Model 76DB/77B User Guide
Studio Technologies, Inc.
7. To complete the process the configuration mode must be exited. This is performed by again pressing and holding
the configure button for two seconds.
The new reference level is now stored
in the Model 76DB’s nonvolatile memory. Only by repeating the entire procedure can the value be changed.
Once the configuration mode has been exited, the monitor outputs will again become
active. Confirm that the correct level has
been stored by pressing the reference level
button. The SPL meter should display the
desired level. If not, repeat the calibration
procedure to achieve the desired goal.
You might wonder why you have to press
and hold the reference level button for five
seconds before the selected value is recognized. This is provided specifically so
that unauthorized users won’t accidentally
change the reference level while they experiment with the configuration mode. Only
if you know the “secret” will you be able to
store a new value.
Overall Display Mode
The Model 77B’s 4-digit numeric display
can be configured to display the post-fader
surround monitor output level in either an
attenuation mode or an SPL mode. In the
attenuation mode the output level is shown
as a reduction in level, in dB, relative to
the maximum output level. When the rotary
control is used to set the output level to its
maximum the display will show 0.0. As the
rotary control is moved in the counterclockwise direction the display will show negative
values, reaching –70.0 before the full mute
function automatically mutes the outputs.
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
Issue 4, November 2010
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for Surround
pressure level (SPL). Used in conjunction
with the reference level in dB SPL configuration and the stored reference level, SPL
mode allows a user to see a visual representation of the SPL level that is present
in the listening environment. While it takes
a little more care to correctly implement
the SPL display mode, it can offer an enhanced experience for StudioComm users.
Reference Level in dB SPL
The reference level in dB SPL configuration allows a specific SPL value to be
associated with the stored reference level
value. In this way whenever the monitor output is at the reference level, either
through activating the reference level function or manually adjusting the rotary level
control, the Model 77B’s display will show
the configured SPL level. Whenever the
monitor output is not at the reference value
the display will show the current value, in
dB, relative to the reference level. The reference level in dB SPL can be configured
over a range of 70.0 to 100.0 dB in 1.0-dB
steps. In many applications selecting a
value of 85 would be appropriate, reflecting the widely used audio-for-picture 85 dB
monitoring reference level. (Typically this
85 dB is really 85 dBC, indicating that a
C-weighting filter has been applied to the
measurement.) Other common reference
SPL values, such as 82 dB and 87 dB, are
well within the allowable range.
Dialnorm Reference Level
The dialnorm reference level parameter
is provided so that the StudioComm system can be configured to match a facilities’
or “plant” default dialnorm level. This value
is used as a reference against which the
post-fader surround monitor output level
will, if enabled, be adjusted up or down
Issue 4, November 2010
Page 22
in response to an incoming dialnorm value.
The dialnorm reference level parameter
can be adjusted over the entire –31 to
–1 dB range but typical values will be in
the range of –27 to –24. Implementation
purists might want to select –31 dB as it
may well be the “truest” implementation of
the dialnorm scheme. In this way the system will, when enabled, reduce the monitor
output level whenever dialnorm is different
than –31 dB. But as bar fights have broken
out over decisions such as this we’ll leave
the choice up to you! For additional information about dialnorm refer to the Technical Notes section of this user guide.
Dialnorm-Data-to-SurroundInput Assignment
For correct operation the connected Dolby
E dialnorm data must be assigned to work
in conjunction with its associated surround
input. In this way the dialnorm data will
only display, and level changes will only
take place, when the appropriate surround
input is selected by an operator.
Dim Level
The dim function is used to reduce the
post-fader surround monitor output level
by a preset amount. The reduction is in dB
relative to the post-fader surround monitor
output’s current level. There are four dim
level values available: –10.0, –15.0, –20.0,
and –25.0 dB.
Remote Mute All
Two configuration choices are associated
with the remote mute all function: disabled
and enabled. To utilize the remote mute all
function simply requires you to select the
enabled setting.
Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
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 monitor output
can be controlled using the remote control
input.
Input Delay
A time delay can be added to the input
signals, allowing compensation for delays
that may be present on associated video
signals. The selected time delay applies
to all input signals and cannot be applied
selectively. The configured delay time is
referenced to a sample rate of 48 kHz.
In the case of input signals with a sample
rate of 48 kHz the delay range is 0 to 340
milliseconds 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.
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
Model 76DB/77B User Guide
Studio Technologies, Inc.
offset level sets the amount of decrease (attenuation) that the non-soloed channels will
experience when a channel is active in the
channel pop solo mode.
LFE Downmix Mode
By default, when the 5.1 to stereo downmix
function is active the LFE channel associated with a surround input is muted. This
removes LFE content from the “downmixed”
signal. In most applications this is appropriate. However, for special situations a configuration mode allows the LFE channel to be
part of the downmix signal flow. When the
LFE downmix mode is enabled, if surround
input A or B is the 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
LFE output channel will still mute when 5.1
to stereo downmix is active.
Pre-Fader Surround Monitor
Output Mode
The pre-fader surround monitor output can
be configured as to its place in the Model
76DB’s signal flow. The choices are pre- or
post-downmix. In the pre-downmix mode
the output channels will not be impacted
by the state of the downmix functions. This
setting would be appropriate if the pre-fader
surround monitor outputs were being routed
to a storage system, routed to another facility, etc. In this case the action of an operator
enabling or disabling the downmix functions
won’t impact the pre-fader surround monitor
output signals. If the post-downmix mode
is selected the pre-fader surround monitor
outputs will reflect the actions of the downmix functions. This choice would be correct
if, for example, level meters were connected
Issue 4, November 2010
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for Surround
to the pre-fader surround monitor outputs. In
this scenario an operator would want to visually observe the actions that the downmix
functions impart on the signals.
current device address. The rotary level
control is used to select the desired device
address; the LEDs will respond accordingly. Refer to Figures 7 and 8 for details.
Restore Factory Defaults
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.
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 a minimal 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. Model 71 units have a
default address of A4; Model 77B unit’s have
a default address of A1. This ensures that, in
most cases, no change will have to be made.
A small button is located on the back of
each Model 71 Control Console, adjacent
to the 9-pin D-sub connector. Pressing and
holding this button for two seconds places
this specific unit in its configuration mode;
normal operation of the Model 76DB and
other connected Model 71 and Model 77B
units will continue. When a Model 71 enters
its configuration mode its three LEDs will no
longer perform their usual functions. Instead
the status LED will blink to indicate that configuration mode is active. The dim and reference level LEDs will display the Model 71’s
Issue 4, November 2010
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Figure 7. Model 71 Control Console Front and
Back Panels
Address
Dim LED
Reference Level LED
A1
OFF
OFF
A2
OFF
ON
A3
ON
OFF
A4
ON
ON
Figure 8. Model 71 Device Address Chart
Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
Configuration—Entering and Exiting Configuration Mode
and hold the configuration
 Press
button for 2 seconds to enter or
exit the configuration mode.
These LEDs will
light alternately
when configuration
mode is active.
Model 76DB/77B User Guide
Studio Technologies, Inc.
Issue 4, November 2010
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for Surround
Configuration—Model 77B Device Address, Stereo Input C
Sample Rate Converter, and Auxiliary Stereo Monitor Output
Nominal Level
and hold the Auxiliary Output
 Press
Enable button to display and select the
Model 77B’s device address, stereo input
C sample rate converter, and auxiliary
stereo monitor output nominal level.
This LED displays the configuration of the stereo
input C sample rate converter (SRC). LED not
lit means SRC is bypassed; LED lit means SRC
enabled. Use the button to change the configuration.
Use the input buttons to select the nominal level
of the auxiliary stereo monitor output.
LED Group 1-3 lit means the output level is 0 dB;
LED 1/4 lit means the output level is –6 dB;
LED 2/5 lit means the output level is –12 dB;
LED 3/6 lit means the output level is –18 dB.
Use the level control to change this specific
Model 77B’s device address. Address can
be either A1, A2, A3, or A4.
Default:
Device address A1.
Stereo input C sample rate converter enabled.
0 dB auxiliary stereo monitor output nominal level.
Note:
The Model 77B’s device address is the only parameter stored in the Model 77B. All other parameters are
stored in the Model 76DB.
Issue 4, November 2010
Page 26
Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
Configuration—Sync Source, Sync Input Termination,
Audio-Synced-to-Video Sample Rate, and Monitor Output Types
This LED displays the configuration of
the sync input termination. LED not lit
means sync input is not terminated; LED
lit means terminated with 75 ohms. Use
the button to change the configuration.
Use the Channel Solo C and LFE
buttons to select the pre-fader
surround/stereo input C direct
monitor output type. Use the
buttons to change the configuration. C LED lit means AES3id
(75 ohms/1 Vpp); LFE LED lit
means AES (110 ohms/5 Vpp).
Use the Channel Solo LS and RS
buttons to select the post-fader surround/auxiliary stereo 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 to
 Press
display and select the sync source, sync
input termination, audio-synced-to-video
sample rate, and 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 monitor output type AES3 (110 ohms/5 Vpp).
Post-fader surround/auxiliary stereo monitor output type AES3 (110 ohms/5 Vpp).
Model 76DB/77B User Guide
Studio Technologies, Inc.
Issue 4, November 2010
Page 27
for Surround
Configuration—Input Select Buttons
When an input button is pressed use the L
and R buttons to assign stereo input A to
that button. Both L and R LEDs lit means
stereo input A is assigned to that button
as a stereo source; L LED only lit means
channel 1 of stereo input A is routed to the
center output and channel 2 is not used;
R LED only lit means channel 2 of stereo
input A is routed to the center output and
channel 1 is not used.
When an input button is pressed use the C
and LFE buttons to assign stereo input B to
that button. Both C and LFE LEDs lit means
stereo input B is assigned to that button as a
stereo source; C LED only lit means channel
1 of stereo input B is routed to the center
output and channel 2 is not used; LFE LED
only lit means channel 2 of stereo input B is
routed to the center output and channel 1 is
not used.
When an input button is
pressed use the LS button
to assign stereo input C to
that button. Both LS and RS
LEDs lit means stereo input
C is assigned to that button
as a stereo source. Individual stereo input C channels
cannot be routed to center
output.
When an input
button is pressed
use the 5.1 to
Stereo button to
assign surround
input A to that
button. Use the
Stereo to Mono
button to assign
surround input B
to that button.

Press and hold an input button to display and select which input
source is assigned to that button in Group 1-3. Press and hold both
the group select button and an input button to display and select
which input is assigned to that button when Group 4-6 is active.
Default:
Surround input A assigned to input 1.
Surround input B assigned to input 2.
No input assigned to input 3 (disabled).
Stereo input A assigned to input 4.
Stereo input B assigned to input 5.
Stereo input C assigned to input 6.
Note:
If no input is assigned to an input button that button is disabled.
Issue 4, November 2010
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Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
Configuration—Reference Level
and hold the Reference Level button for 5 seconds to take a
 Press
“snapshot” of the level control’s setting at the time configuration mode
was entered. The Reference Level LED will flash when the button is
initially pressed and then light solid when the “snapshot” has been taken.
Default:
Reference level set for –60.0 dB post-fader monitor output level.
Note:
The 5-second delay is a safety feature ensuring that the reference level will not be accidently changed.
To permanently store the new value, you must still exit the configuration mode.
Model 76DB/77B User Guide
Studio Technologies, Inc.
Issue 4, November 2010
Page 29
for Surround
Configuration—Overall Display Mode and Reference Level
in dB SPL
Use the Channel Solo L and R buttons to select the
overall display mode. L LED lit means attenuation
mode is selected; R LED lit means SPL mode is
selected. Use the buttons to change the configuration.

Press and hold
the Display
Mode button
to display and
set the overall
display mode
and the reference level in
dB SPL.
Use the level control to adjust
the reference level in dB SPL.
The range is 70.0 to 100.0 dB
in 1.0-dB steps.
Default:
Attenuation display mode selected.
85.0 dB SPL reference level.
Issue 4, November 2010
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Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
Configuration—Dialnorm Reference Level and Dialnorm-Datato-Surround-Input Assignment
Use the Downmix 5.1 to Stereo and Stereo to Mono buttons to assign the
dialnorm data to the appropriate surround input. LED 5.1 to Stereo lit
means dialnorm data assigned to surround input A; LED Stereo to Mono lit
means dialnorm data assigned to surround input B.
and hold the Dialnorm
 Press
Enable button to display and set
the dialnorm reference level and
assign the dialnorm data.
Default:
Use the level control to adjust the
dialnorm reference level. The
range is –31 to –1 dB in 1-dB steps.
–31 dB dialnorm reference level.
Dialnorm data assigned to surround input A.
Model 76DB/77B User Guide
Studio Technologies, Inc.
Issue 4, November 2010
Page 31
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 4, November 2010
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Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
Configuration—Channel Pop Solo Mode Offset Levels, LFE
Downmix Mode, and Pre-Fader Surround Monitor Output Mode

Press and hold the
5.1 to Stereo button to display and
select the channel
pop solo up offset
level, to configure
LFE downmix, and
configure pre-fader
surround monitor
output mode.
When the 5.1 to Stereo button is pressed,
these LEDs display the configuration of the
pre-fader surround monitor output mode.
LED L lit means outputs are pre-downmix;
LED R lit means outputs are post-downmix.
Use the buttons to change the configuration.
When the 5.1 to Stereo button is pressed,
this LED displays the configuration of the
LFE downmix mode. LED not lit means
LFE downmix mode is disabled; LED lit
means enabled. Use the button to change
the configuration.

Press and hold the
Stereo to Mono
button to display
and select the
channel pop solo
down offset level.
When the 5.1 to Stereo button is pressed, use the level
control to adjust the channel pop solo up offset level.
The range is 0.0 to 12.0 in 0.5-dB steps.
When the Stereo to Mono button is pressed, use the level
control to adjust the channel pop solo down offset level.
The range is –0.0 to –12.0 in 0.5-dB steps and full mute.
Full mute is selected by adjusting the level control past
–12.0, at which point the display will show – – – –.
Default:
6.0 dB channel pop solo up offset level.
–6.0 dB channel pop solo down offset level.
LFE downmix disabled.
Pre-fader surround monitor output pre-downmix.
Model 76DB/77B User Guide
Studio Technologies, Inc.
Issue 4, November 2010
Page 33
for Surround
Configuration—Restore Factory Defaults
and hold both the Dialnorm Enable and Dim buttons for 5 seconds
 Press
to restore Model 77B factory defaults. Once defaults have been restored,
the associated LEDs will light. After the buttons are released, configuration mode will be exited and normal operation will resume.
Factory Defaults:
Device address A1.
Stereo input C sample rate converter enabled.
0 dB auxiliary stereo 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 monitor output
type AES3 (110 ohms/5 Vpp).
Post-fader surround/auxiliary stereo monitor output type
AES3 (110 ohms/5 Vpp).
Surround input A assigned to input 1.
Surround input B assigned to input 2.
No input assigned to input 3 (disabled).
Stereo input A assigned to input 4.
Stereo input B assigned to input 5.
Stereo input C assigned to input 6.
Reference level set for –60.0 dB post-fader monitor
output level.
Attenuation display mode selected.
85.0 dB SPL reference level.
–31 dB dialnorm reference level.
Dialnorm data assigned to surround input A.
–20 dB dim level.
Remote mute all enabled.
Remote dim enabled.
Remote auxiliary stereo monitor output on/off enabled.
Input delay 0 ms.
6.0 dB channel pop solo up offset level.
–6.0 dB channel pop solo down offset level.
LFE downmix disabled.
Pre-fader surround monitor outputs pre-downmix.
Warning: Each Model 77B unit must have a unique address. Restoring factory defaults will reset only this specific
Model 77B to address A1. If another connected unit is already configured for address A1, normal system
operation will stop.
Note:
The 5-second button-press delay is a safety feature ensuring that the factory defaults will not be accidently
restored.
Issue 4, November 2010
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Model 76DB/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, especially regarding the
system’s support for dialnorm.
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 monitor output level will always return
to its minimum value. The rotary level control or the reference level button must then
be used to return the system to the desired
post-fader surround monitor output level.
Model 76DB Central Controller
The Model 76DB’s front panel contains
three LEDs. The control console status LED
will light whenever the Model 76DB is communicating 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 power-up sequence.
The metadata status LED will light whenever an active metadata signal has been
connected and valid metadata sync word
information is being received.
The sync status LED will light whenever
a valid timing reference signal is being
received by the Model 76DB. A flashing
sync status LED indicates that a valid sync
signal is not being received.
Model 76DB/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. Other system functions
can also be controlled by means of the
metadata and 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 output, 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
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for Surround
changing between groups will switch between two specific inputs. This allows rapid
switching between, as an example, input 1
and input 6.
The specific sources assigned to the input
buttons depend on the signals connected
to the Model 76DB along with how the system has been configured. Any input 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 monitor outputs. And,
depending on the selected configuration,
they may also impact the pre-fader surround
monitor outputs. Please refer to the Specifications section of this guide 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 a surround (5.1) input
source is selected. Neither of the downmix
Issue 4, November 2010
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functions can be enabled when an input
source configured for monaural is selected.
This is because an input of this type is already monaural and wouldn’t be impacted
by any additional fold down.
The Model 77B associates the state of
the downmix functions with the currently
selected input. For example, if input 2 is
the selected input source and the 5.1 to
stereo downmix function is enabled, this
condition will be “remembered” when
switching to a stereo or monaural input
source. Upon returning to input 2, the 5.1
to stereo downmix function will again
become active.
5.1 to 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 monitor output
channels. The C, LFE, LS, and RS monitor
output channels are muted. By utilizing this
downmix function phase relationships and
inter-channel level issues can be quickly
observed.
Stereo to Mono
The stereo to monaural downmix function
combines the L and R audio channels to
create a single-channel monaural signal.
This signal is sent out the C monitor output
channel while the L, R, LS, RS, and LFE
monitor output channels are muted.
When a surround source has been selected for monitoring, the 5.1 to stereo
Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
downmix function will automatically enable
whenever the stereo to mono downmix
function is enabled. This ensures that an
operator will hear a mono signal created
by folding down all channels associated
with the selected surround input.
Monitor Output General
Functions
Four buttons and one rotary control are
associated with the post-fader surround
monitor output functions. The buttons control operation of the reference level, mute
all, dim, and dialnorm enable functions.
The rotary level control is used to manually
set the post-fader surround monitor output
level. These buttons and the rotary control do not impact the pre-fader surround,
auxiliary stereo, and stereo input C direct
monitor outputs.
Reference Level
The reference level button sets the postfader surround monitor output level to a
preset value. Technical personnel, using
a sound-pressure-level (SPL) meter and
precision signal source, should have set
this level to meet the requirements of the
specific monitoring environment. The LED
associated with the reference level button
will light whenever the function is active.
Whenever the reference level mode is active the rotary level control is disabled. The
4-digit display will indicate the reference
output level. Note that the system’s default
reference level is –60.0 dB so “out of the
box” the Model 77B will display –60.0 when
reference level mode is enabled.
The reference level LED also serves as a
calibration aid. If the reference level mode
is not active, whenever the post-fader surround monitor output level is precisely the
Model 76DB/77B User Guide
Studio Technologies, Inc.
same as that stored for the reference value
the reference level LED will flash. This exact
level can also be reached through the use
of the rotary level control, either by itself or
through the setting of the rotary level control
in conjunction with the dialnorm data and
dim function. Whatever path the output level
takes to reach the reference level value, it
will cause the reference level LED to flash.
Mute All
Pressing the mute all button causes the
six channels associated with the post-fader
surround monitor output to mute. The
4-digit display indicates the mute condition
by showing four dashes (– – – –). The mute
all button is always set to “latch” the function on and off. The LED associated with the
mute all button will light whenever mute all
is active. Note that if mute all is enabled via
the remote mute all function, the mute all
LED will flash.
Dim
The dim function is provided for user convenience, allowing the post-fader surround
monitor output level to be reduced by a
fixed amount. The Model 77B’s configuration mode allows the dim level to be selected from among four choices: –10.0, –15.0,
–20.0, or –25.0 dB. Pressing the dim button
will enable the function. The dim button is
always set to “latch” the function on and off.
The 4-digit display, when selected for output
level mode, will indicate the revised monitor
output level. If the requested “dimmed” output level is equal to or less than –96.0 dB,
the monitor output will go into full mute and
the display will show four dashes (– – – –).
When dim is active the post-fader surround
monitor output level reduction will apply no
matter whether the monitor output level is
being set by the rotary level control or by
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for Surround
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 a surround
signal that has been configured as having
dialnorm associated with it. (This is because dialnorm level data is available only
for that specific source.) When enabled,
as the dialnorm level changes the postfader surround monitor output level will
Issue 4, November 2010
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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 monitor
output level. It is active whenever the reference level function is not active. The level
control provides the ability to adjust the
monitor output level over a 70 dB range.
Technically the rotary level control is a
24-step-per-revolution mechanical encoder. The amount of level change in dB per
step (“click”) will depend on how quickly
Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
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 monitor output channels will automatically mute. As previously discussed,
the 4-digit display indicates the mute condition by showing four dashes (– – – –).
Channel Solo
The channel solo function allows specific
channels to be selected for individual
or group “solo” monitoring. The function
impacts the post-fader surround monitor
outputs, taking place electrically “after”
the source selection, input delay, downmix, and level control functions. Two solo
modes are available, normal and channel
pop. In the normal solo mode the level of
a channel selected for soloing actually
doesn’t change; the solo function causes
the non-soloed 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.
Model 76DB/77B User Guide
Studio Technologies, Inc.
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 press-to-enable/
press-to-disable “latching” mode. The LED
associated with a soloed channel is used
to indicate that solo is active.
The auxiliary stereo 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 monitor output enable
button for a few seconds until all the channel solo LEDs light in the desired manner;
steady to indicate normal solo mode and
flashing for channel pop solo mode. Once
the state of the LEDs change (steady-toflashing or vice-versa) the desired solo
mode becomes active and the button can
be released. The selected solo mode will
be maintained even after the system is
powered down and subsequently powered up. In the normal solo mode a soloed
channel will have its associated LED light
steadily. In the channel pop solo mode a
soloed channel will have its associated
LED flash.
For user flexibility, more than one output
channel can be selected for soloing at a
time. The Model 77B even allows all six
monitor output channels to be simultaneously selected for solo. This would seem
to be an “all soloed so none are soloed”
mode. But this condition is specifically
allowed so that when in the normal solo
mode an output channel mute function
can be provided. By first soloing all output
channels an operator can then “un-solo”
specific channels, directly muting them. It’s
a bit confusing to describe in words but is
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for Surround
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
Output
As has been previously discussed in this
user guide, the auxiliary stereo monitor
output is a stereo (2-channel) output signal
that can be used for special applications.
The source for this output is stereo input C.
Using the auxiliary stereo monitor output
enable button stereo input C can be routed
to the auxiliary stereo monitor output as
desired. The button functions in an alternate action manner to change the current
state of the output. An associated LED
lights whenever the auxiliary stereo monitor
output is active. No level control, downmix,
or other Model 77B-supported functions will
impact the auxiliary stereo monitor output.
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 monitor output or the
dialnorm level. The display mode button is
used to select the desired mode. Two LEDs
are associated with this button, indicating
which mode is active. The button can also
be used to display the Model 76DB’s current sample rate.
Both modes will indicate level in dB. What
the digits actually represent will depend on
how the Model 77B has been configured.
When selected for the output level display
mode, the post-fader surround monitor
Issue 4, November 2010
Page 40
output level 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 output level as an
attenuation value in reference to the maximum output. This is in the form of 0.5-dB
steps less than the maximum of 0.0 dB.
So a display of –40.5 would indicate that
the post-fader surround monitor output
is 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 monitor output
level in dB SPL, the 4-digit display will
always show the output level in positive
numbers. These numbers are intended to
represent the sound pressure level in dB
SPL, a figure that should directly relate to
the actual sound pressure level that the
loudspeaker system is presenting to users.
(Typically, the level value would actually
be in dBC, the C-weighted sound pressure
level.) When the reference level button is
enabled, or the rotary level control is set so
that the reference level has been reached,
the display will typically show something
in the range of 82 to 87 dB. Assuming that
the monitoring environment has been correctly calibrated, this would indicate that an
average listening level of 85 dB, for example, had been achieved.
Dialnorm Display
When the 4-digit display is set for the
dialnorm display mode a much different
piece of information will be shown to the
Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
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-forpicture 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
9. This feature can be useful in broadcast
transmission and distribution applications.
In theory, any time the dot in the lower-right
corner is not lit the current dialnorm level
value is causing a level adjustment to take
place. This level adjustment may be taking
Model 76DB/77B User Guide
Studio Technologies, Inc.
Figure 9. Incoming Dialnorm Level Match “Dot”
place on the post-fader surround monitor
outputs if the dialnorm enable function is
active, as it would be for downstream users
of the broadcast signal.
Note that if a valid dialnorm source is not
available the 4-digit display, when selected
to display dialnorm, will show four dashes
(– – – –). This could be due to a problem
with the metadata signal connected to the
Model 76DB Central Controller. But more
frequently this will simply be the normal result that occurs when the Model 77B’s input
is not selected for the metadata-associated
surround input source.
Channel Pop Solo Display
As has been previously discussed, the
channel pop solo mode offers a unique way
of sonically highlighting an individual channel. A channel selected for soloing in this
mode will have its level increased while the
other non-soloed channels will be reduced
in level. To highlight this condition, when
the display mode is set for output level the
letters POP will appear in the 4-digit display
whenever a channel is actively being “pop”
soloed. This ensures that a user will understand that the monitor outputs no longer
represent the true inter-channel level
relationships.
Issue 4, November 2010
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for Surround
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 76DB and then configured for operation. The functions are remote mute all,
remote dim, and remote auxiliary stereo
monitor output on/off. When an external
signal activates remote mute all the LED
on the Model 77B associated with the
mute all button will flash. If mute all was
already active when the remote mute all
function is activated, the LED will change
from being steadily lit to flashing.
When an external signal activates remote
dim the LED on the Model 77B associated
with the dim button will flash. If dim was already active when remote dim is activated,
the LED will change from being steadily lit
to flashing.
When an external signal activates the
remote auxiliary stereo monitor output 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.
Issue 4, November 2010
Page 42
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 monitor output
level. 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.
Rotary Level Control
The rotary level control is used to manually
adjust the post-fader surround monitor output level. Its operating characteristics are
identical to those of the Model 77B Control
Console, discussed earlier in this section.
Dim
The dim function allows the post-fader
surround monitor output level to be reduced by a fixed amount. Its operating
characteristics are identical to those of the
Model 77B Control Console, discussed
earlier in this section.
Reference Level
The reference level button sets the postfader surround monitor output level to a
preset value. Its operating characteristics
are identical to those of the Model 77B
Control Console, discussed earlier in this
section.
Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
Technical Notes
32.0, 44.1, 48.0, 88.2, 96.0, 176.4, or
192.0—will momentarily be displayed.
Loss of Sync
Any time that a valid sync signal is not
connected to the Model 76DB the monitor
outputs will automatically revert to an internally generated sample rate of 48 kHz with
no digital audio content present. This audio
“black” signal will allow most connected
equipment to continue to function correctly,
of course with no meaningful audio signal
present. As soon as a valid sync signal is
again connected to the Model 76DB the
monitor outputs will automatically switch to
their correct sample rate and audio signals
will again be present.
The Model 76DB 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 76DB’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 76DB the sync
status LED, located on the unit’s front panel, will light. The sample rate of the monitor
output channels will reflect the rate of the
sync input and, if a video sync source is
utilized, the configured rate.
If a valid sync signal is not present several visual indications will be provided. On
the Model 76DB the sync status LED will
flash. On all connected Model 77B Control Consoles the 4-digit LED display will
cease normal operation, instead alternating between the words no and sync. When
a valid sync signal is again connected the
sync status LED will light steadily. On the
Model 77B units the word sync will momentarily be displayed followed by a brief
display of the monitor output sample rate.
The sample rate will display as 32.0, 44.1,
48.0, 88.2, 96.0, 176.4, or 192.0, reflecting
the impact of the sync source rate and the
Model 76DB’s configuration.
If during normal operation the sync source
changes from one valid rate to another
a visual indication is provided. On the
Model 77B units the new sample rate—
Model 76DB/77B User Guide
Studio Technologies, Inc.
Power Down
Great care was taken in the Model 76DB’s
design to minimize the chance that clicks,
pops, or other objectionable audio signals
will be present on the monitor outputs.
A power-down circuit supplies the main
microcontroller integrated circuit with an
indication that a power loss is imminent.
When this condition is detected the monitor outputs automatically switch to silence
(audio “black”) in preparation for a complete loss of signal.
Power-Up Messages and
Error Codes
Upon mains power being applied to the
Model 76DB all connected Model 77B
units will go through a power-up sequence.
The sequence starts by each of the individual LEDs lighting in a “walk-through”
sequence. Then the 4-digit display tests
all its LED segments. Finally, a set of
messages provide details on the specific
Model 77B and connected Model 76DB
software versions:
Issue 4, November 2010
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for Surround
1. Displays 77b
2. Displays Model 77B software version
3. Displays Model 77B unit address
(A1, A2, A3, or A4)
4. Displays 76db
5. Displays Model 76DB main software
version
6. Displays FPgA
7. Displays 76DB’s logic device (FPGA)
software version
After a successful system power-up sequence normal operation will then commence. Should a problem be encountered
during power up one of two error codes may
show on the Model 77B’s 4-digit display. If
Err1 displays it indicates that communication is not taking place with the Model 76DB.
The most likely cause would be incorrect
wiring of the data pair linking the two units.
Err2 indicates that the Model 76DB is having problems with its internal logic device.
(A high-speed field-programmable gate
array (FPGA) serves as the digital “heart”
of the Model 76DB and without it no audio
activity can occur.) The only way to remedy
this condition is to first try removing and
reconnecting mains power. (And that’s a
long-shot as to whether it would accomplish
anything.) If the error code continues to be
displayed the Model 76DB must be returned
to the factory for service. Note that for the
vast majority of StudioComm systems neither of these error codes, especially Err2,
will ever appear.
Sample Rate 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
Issue 4, November 2010
Page 44
re-synchronized to match the Model
76DB’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 offer “single-chip” SRC
solutions and the Model 76DB uses an
excellent one from AKM. The technical capabilities of the Model 76DB’s SRC function is stated in this way: the sample rate
of an input signal can range from 1/6 to
six times the Model 76DB’s output sample
rate, with the additional restriction that it
must be no less than 8 kHz and no more
than 216 kHz. The Model 76DB’s output
sample rate is determined by the external
timing reference (sync) signal and, if required, a configured value. If a word clock,
DARS (AES11), or AES3id signal is the
designated sync source its rate will be
the Model 76DB’s output sample rate. If a
video sync signal is connected, the Model
76DB’s sample rate is selected as part of
the configuration process.
So in practice what can the SRC function
accomplish? If the output sample rate is
48 kHz then a signal connected to stereo
input C can have a sample rate from 8 to
216 kHz. Or, as another example, if the
Model 76DB’s output sample rate is 96
kHz a signal connected to stereo input C
can have its sample rate range from 16 to
216 kHz.
As useful as allowing one disparate sample rate to be converted to another, it may
be the ability of the Model 76DB’s SRC
function to re-synchronize a signal that
proves most valuable. In typical broadcast
applications all signals will have a sample
rate of 48 kHz. A Model 76DB and all of its
normally connected input signals will be
“locked” to the main timing reference signal
Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
that supports the 48 kHz sampling rate.
But, as an example, a signal associated
with a portable device, while at a 48 kHz
sampling rate, may not be synchronized
(“genlocked”) to the “house” reference.
Connecting this signal to stereo input C
will cause the SRC function to “lock” it to
the Model 76DB’s rate, thus allowing it to
be monitored over a loudspeaker system.
In addition, the stereo input C direct monitor output can be connected to other devices that find need for the now-synchronized
signal. In some cases it may be useful to
connect the stereo input C direct monitor
output to the input of a signal router, allowing an entire facility to access the signal.
Dialnorm
A source of Dolby E metadata can be connected to the Model 76DB Central Controller. Within this flow of metadata frames can
be a “dialnorm” level value that’s associated with one of the Model 76DB’s 5.1
surround input signals. When this surround
input is selected for monitoring its associated dialnorm level value can be displayed
by the Model 77B Control Console. It can
also be used to control the level of the
post-fader surround monitor output.
Technically, the metadata is in the form
of a 115.2 kbit/s RS-485/RS-422 signal
that contains a number of data elements,
including one or more that represent the
average dialog level (dialog normalization or dialnorm) in the audio program
signals being carried over the digital audio
portion of the related Dolby E interface.
These dialnorm levels are associated with
specific programs within the 8-channel
audio “stream.” Firmware within the Model
76DB is able to parse (separate) the data
elements, specifically separating the first
Model 76DB/77B User Guide
Studio Technologies, Inc.
dialnorm level value in the metadata frame
from the one or more that may be present
later in the frame. To clarify, all dialnorm
level elements that occur later in the same
metadata frame are ignored. This method
was selected as it was assumed that the
first dialnorm level element will always be
associated with a 5.1 program. There’s
a technical basis for why this should be
true. In Dolby E a 5.1 program is always
assigned to the first six channels (channels 1-6). While there may be separate
dialnorm values associated with audio
channels 7 and 8, they are not relevant for
correct StudioComm system operation.
Model 76DB to Control
Console Connections
Figure 6 gives a detailed description of the
signals that connect the Model 76DB Central Controller to the one or more Model
77B or Model 71 Control Consoles. The
Model 76DB provides a +12 volt DC power
source for use by the control console’s
circuitry. The DC output is current-limited
to minimize the chance that a short-circuit
condition will damage the Model 76DB’s
circuitry. An asynchronous, bi-directional
data interface links the connected units.
The RS-485 hardware connection scheme
operates at a rate of 115.2 kbit/s and uses
an 8-N-1 data format. The Model 76DB
communicates with each Model 77B and
Model 71 unit 20 times per second, receiving button and rotary level control information and sending LED and 4-digit display
status data.
“Hot” Disconnection of
Control Consoles
There’s no problem relocating one or more
Model 77B or Model 71 Control Consoles
Issue 4, November 2010
Page 45
for Surround
while the StudioComm system is operating. You can disconnect the 9-pin interconnecting cable, move the unit (or units),
and then reconnect without issue. Upon
disconnection of all control consoles the
Model 76DB Central Controller will mute
the monitor output channels as well as
saving the current operating parameters.
No clicks, pops, or other noises will occur
when the Model 77B or Model 71 units
are again connected. The control consoles
will go through their standard power-up
sequence and then normal operation will
resume.
Channel Status, User, and
Validity Bits
The non-audio bits that are part of the
AES3/AES3id monitor output channel data
are actively controlled by the Model 76DB’s
software. The Channel Status bits use the
Professional Use of Channel Status block.
They indicate a word length of 24 and the
current sample rate. The correct CRC is
also calculated and inserted. The User bits
are always set to 0. When a valid timing
reference (sync) source is recognized by
the system the Validity bits will be set to 1.
The Model 76DB’s hardware is capable of
routing the C/U/V bit information from surround input A L/R, stereo input C, and the
sync input to the main logic device (FPGA)
and then on to the digital audio transmitter
(DIT) integrated circuits. This is provided
for future use and is not active at this time.
Issue 4, November 2010
Page 46
Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
Specifications
Downmix:
Functions: 5.1 to stereo, stereo to mono
Model 76DB Central Controller
5.1 to Stereo: LS @ –3 dB summed with L;
RS @ –3 dB summed with R;
C @ –6 dB summed with L and R;
LFE @ –6 dB summed with L and R (if enabled);
C, LFE, LS, and RS monitor outputs mute
General Audio:
Supported Sample Rates: 32, 44.1, 48, 88.2, 96,
176.4, and 192 kHz
Word Length: 24 bits maximum
Input-to-Output Latency: one sample (e.g., 0.021
milliseconds @ 48 kHz sample rate)
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)
Digital Audio Inputs: five (18 audio channels)
Configuration: two surround (5.1) and three stereo
Dolby E Metadata Input:
Type: RS-485/RS-422
Type: AES3id-2001/SMPTE 276M (unbalanced
75 ohms/1 Vpp)
Data Rate/Format: 115.2 kbit/s, 8-N-1
Internal Processing: 32 bits
Dynamic Range: >135 dB
Connectors: BNC (per IEC 60169-8 Amendment 2)
Connector: 9-pin D-subminiature female (DE-9F),
shared with remote control inputs
Sample Rate Conversion (SRC):
Application: available on Stereo Input C
Control Console Interface:
Type: RS-485, 115.2 kbit/s, 8-1-N
Input Sample Rate Range: 8 to 216 kHz, limited
to 1/6 to 6 times the output sample rate
Polling Interval: 50 milliseconds
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: four (16 audio channels)
Configuration: organized as two surround (5.1),
one auxiliary stereo, and one stereo input C direct
output
Type: AES3 (110 ohms/5 Vpp) or AES3id/SMPTE
276M (75 ohms/1 Vpp), selectable
Connector: 25-pin D-subminiature female (DB-25F)
Configurable Delay: 0 to 340 milliseconds @
48 kHz sample rate (scaled up or down depending
on actual sample rate)
Power: 12 volts DC, 500 milliamperes maximum
Connector: 9-pin D-subminiature female (DE-9F)
Remote Control Inputs: three
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
AC Mains:
Requirement: 100 to 230 V, 50/60 Hz, 15 watts
maximum
Connector: 3-blade, IEC 320 C14-compatible
(mates with IEC 320 C13)
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 76DB/77B User Guide
Studio Technologies, Inc.
Issue 4, November 2010
Page 47
for Surround
Model 77B Control Console
Application: up to four Model 77B Control
Consoles can be connected to a Model 76DB
Central Controller
Power: 12 volts DC nominal (9 volts DC minimum),
maximum current 100 milliamperes, provided by
Model 76DB Central Controller
Control Data:
Type: RS-485
Data Rate/Format: 115.2 kbit/s, 8-N-1
Connector: 9-pin D-subminiature female (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)
Model 71 Control Console
Application: up to three Model 71 Control
Consoles can be connected to a Model 76DB
Central Controller
Power: 12 volts DC nominal (9 volts DC minimum),
maximum current 35 milliamperes, provided by
Model 76DB Central Controller
Control Data:
Type: RS-485
Data Rate/Format: 115.2 kbit/s, 8-N-1
Connector: 9-pin D-subminiature female (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.
Issue 4, November 2010
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Model 76DB/77B User Guide
Studio Technologies, Inc.
for Surround
Appendix A—Connection Pin-Out
Charts
Connections
TASCAM® Signal
Channel High (+)
Signal
Pin
Direction
Signal
Low (–)
Shield
Data + (RS-485)
1
To/From Models 77B/71
Pre-Fader L/R
1
24
12
25
Data – (RS-485)
6
To/From Models 77B/71
Pre-Fader C/LFE
2
10
23
11
Data Shield
2
To/From Models 77B/71
Pre-Fader LS/RS
3
21
9
22
DC + (12 V)
4
To Models 77B/71
Stereo Input C Direct
4
7
20
8
DC – (12 V Return)
9
To Models 77B/71
Post-Fader L/R
5
18
6
19
DC Power Shield
5
To/From Models 77B/71
Post-Fader C/LFE
6
4
17
5
Post-Fader LS/RS
7
15
3
16
Auxiliary Stereo
8
1
14
2
Notes: 1) All signals transformer-coupled digital audio;
selectable for AES3 or AES3id compatibility.
Note: Connector type on Model 76DB is 9-pin D-subminiature
female (DE-9F). Connector uses 4-40 threaded inserts
for locking with mating plug.
Connections between Model 76DB and
Model 77B and Model 71
2) Connector type on Model 76DB is 25-pin
D-subminiature female (DB-25F). Installer must
provide male (DB-25M). Connector uses 4-40
threaded inserts for locking with mating plug.
3) Wiring scheme follows TASCAM DA-88 convention.
Standard DA-88-type wiring harnesses are directly
compatible, with the possible exception of 4-40 screw
threads being required.
Connections for Monitor Outputs
Signal
Pin
Direction
Data + (RS-485/RS-422)
7
Input
Data – (RS-485/RS-422)
2
Input
Data Shield
1
Shield
Remote Mute All
5
Input
Remote Dim
6
Input
Remote Aux Stereo Monitor Out On/Off
8
Input
Remote Spare
9
Input
Remote Common
4
Common
Note: Connector type on Model 76DB is 9-pin D-subminiature
female (DE-9F) Connector uses 4-40 threaded inserts
for locking with mating plug.
Connections for Metadata and Remote Control
Inputs
Model 76DB/77B User Guide
Studio Technologies, Inc.
Issue 4, November 2010
Page 49
for Surround
Appendix B—Sync Input Sources
The Model 76DB’s sync input has been tested and confirmed for correct operation with the
following sync signals:
Word Clock: Square wave signal with rate of 32, 44.1, 48, 88.2, 96, 176.4, or 192 kHz.
DARS (AES11) or AES3id: Signal with sample rate of 32, 44.1, 48, 88.2, 96, 176.4, or
192 kHz.
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 4, November 2010
Page 50
Model 76DB/77B User Guide
Studio Technologies, Inc.
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