Model 76DA/77 User Guide Issue 9, May 2014
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Issue 9, May 2014 Model 76DA/77 User Guide
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Introduction
What This User Guide Covers
This User Guide is designed to assist
you when installing and using the Model
76DA Central Controller and one or more
associated Model 77 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,
post-production, and broadcast facilities.
And with audio-with-picture applications
becoming so prevalent, additional monitoring challenges have arisen. Studio Technologies has addressed these needs with
the StudioComm for Surround Model 76DA
Central Controller and the Model 77 and
Model 71 Control Consoles. With digital
audio inputs, digital and analog monitor
outputs, support for multiple user control
surfaces, and an extensive set of operating
resources it’s a simple task to integrate a
monitoring system into virtually any facility.
The carefully selected group of features,
including surround and stereo inputs, configurable input-signal time delay, multiple
pre- and post-fader outputs, configurable
downmix and mute/solo functions, and bass
management, along with a multi-format
sync input, make the system powerful yet
simple to operate. And by using the best of
contemporary technology, as well as following rigorous design practices, the system’s
audio quality is excellent.
A StudioComm for Surround system starts
with the Model 77 Control Console. It’s the
system’s “command center” and is designed
to reside at an operator’s location, allowing fingertip selection of all monitoring
functions. Numerous LED indicators provide complete status information. A 4-digit
numeric display indicates the post-fader
monitor output level in real time. A major
strength of the Model 77 is its ability to
configure, under software control, many
important operating parameters. Intended
for secondary monitoring locations, the
Model 71 Control Console is a compact
user control surface. It provides three of
the most basic functions: a rotary level
control, dim on/off button, and reference
level on/off button.
While many installations will use only one
Model 77 Control Console, up to three
additional Model 77 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 76DA
provides power for all connected Model 77
or Model 71 units.
The core of this StudioComm for Surround
system is the Model 76DA Central Controller. The one-rack-space unit contains
circuitry that supports digital audio inputs,
digital and analog monitor outputs, processing, and the user interface. The Model
76DA provides two surround (5.1) and
three stereo digital audio inputs. These
unbalanced digital inputs are AES3/
SMPTE 276M-compliant; sources of this
type are ubiquitous in most post-production and broadcast environments. The inputs allow a sample rate of up to 192 kHz
and a bit depth of up to 24 to be directly
supported. Circuitry associated with one
of the stereo inputs provides sample rate
conversion (SRC) capability, allowing a
wide range of digital audio sources to be
monitored. Up to 340 milliseconds of input
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delay can be selected to compensate for
processing delays in an associated video
path. For flexibility, two delay values can be
configured, allowing real-time selection as
desired. A number of different signals can
serve as the Model 76DA’s digital audio
timing reference. For synchronization with
a master timing reference a dedicated
source of word clock, DARS (AES11), bilevel 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.
A range of digital and analog surround (5.1)
and stereo digital monitor outputs are provided. The post-fader surround and stereo
digital and analog monitor outputs are intended for connection to monitor loudspeaker systems. The pre-fader surround digital
monitor output can be used with metering
systems that require signals that aren’t
impacted by level control or other monitoring functions. The stereo input C direct
digital monitor output allows an installation
to directly access the SRC capabilities.
For installation flexibility the digital monitor
outputs can be configured for compatibility with equipment that requires balanced
or unbalanced AES3 digital audio signals.
When selected for balanced AES3 compatibility the output impedance is 110 ohms
with a signal level of 5 volts peak-to-peak
(Vpp). For unbalanced AES3 operation
the impedance is 75 ohms and the level
is 1 Vpp.
A sophisticated bass management function is integral to the Model 76DA’s design
and can be enabled if desired. It can apply
to both the surround and stereo digital and
analog post-fader monitor output channels.
Note however that the bass management
function is only supported at sample rates
of 44.1, 48, 88.2, and 96 kHz. The overall
goal of bass management is very simple:
ensure that the entire audio bandwidth of
all channels can be accurately monitored.
Many loudspeaker systems have inherent
low-frequency limitations, preventing a true
picture of the source material from being
presented. To overcome this, the low-
Figure 1. Model 76DA Central Controller Front Panel
Control console
status LED
Figure 2. Model 76DA Central Controller Back Panel
A
C mains
input
Remote control inputs
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To /from
Models 77 & 71
Control Consoles
Digital monitor
outputs
Analog monitor
outputs
Sync
Input
Stereo
Input C
Surround Input B
Surround Input A
Sync status
LED
Stereo Input A and
Stereo Input B
Mute/solo
mode
for Surround
Channel mute/solo
Downmix
Input source
select
Figure 3. Model 77 Control Console Front Panel
frequency energy from the five surround
and two stereo channels can be separated
and then routed to the subwoofer loudspeaker. Several of the bass management
functions can be configured to match the
requirements of specific installations.
Great care was taken in designing the
system’s architecture, ensuring that the
character of the audio input signals is preserved. All audio processing, including bass
management, is performed in 32 bits using
a high-speed field-programmable gate array
(FPGA) integrated circuit.
The Model 76DA occupies one space (1U)
in a standard 19-inch rack. Digital audio
sources are interfaced with the Model 76DA
using nine BNC connectors. A tenth BNC
connector is used by the sync source.
Digital and analog monitor output signal
connections are made using two 25-pin
female D-subminiature connectors. One
9-pin female D-subminiature connector
is used to connect the Model 76DA with
up to four Model 77 or Model 71 Control
Consoles. A second 9-pin female “D-sub”
Monitor output
level display
Post-fader surround
monitor output
• Surround/stereo
erence level
• Ref
• Mute all
• Dim
• Rotary level control
connector is used to interface with remote
control signals. AC mains power is
connected directly to the Model 76DA,
with an acceptable range of 100 to 230
volts, 50/60 Hz.
Additional Details
The Model 77 provides five buttons and associated LEDs for selection of the surround
and stereo input sources to be monitored.
While in most cases only one input source
will be monitored at a time, stereo input C
can be selected for simultaneous monitoring
with one of the two surround or other two
stereo inputs. This allows the two selected
inputs to be combined (“summed”).
It’s interesting to note that while each of the
two surround inputs has an LFE channel
associated with it, the “.1” post-fader digital
and analog surround monitor outputs are
designated as SUB (subwoofer), rather than
LFE. This terminology was carefully selected
to highlight the fact that this output channel
may include more than just LFE content.
The bass management function, if enabled,
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will redirect low-frequency energy from the
main input channels, combing it with the
LFE content before routing the sum to the
digital and analog subwoofer outputs.
The post-fader surround and stereo digital
and analog monitor output levels can be
controlled by way of a large, easy-to-use
rotary control. The control, actually a digital
encoder, allows level selection in precise
0.5-dB steps. The auto mute all function
causes the post-fader surround and stereo
monitor output channels to automatically
mute whenever the output level control
reaches maximum attenuation. Using the
reference level function, the post-fader
surround and stereo monitor output levels
can be set to a pre-configured value. This is
provided for audio-with-picture applications
that require a specific monitor output level.
The reference level is easily configured
by taking an electronic “snapshot” of the
desired monitor output level. For operator confirmation a 4-digit LED readout can
display the level of the post-fader surround and stereo 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 and stereo digital and analog
monitor output levels 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 and stereo monitor output channels
to be simultaneously muted. The channel
mute/solo section provides post-fader surround and stereo channel monitoring control, allowing a single channel to be muted
or monitored. Multiple channels can also
be simultaneously selected for muting or
“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 post-fader digital and analog monitor output channel to be raised while the
level of the other channels is reduced. This
helps to emphasize the content on one
channel without fully muting the others.
Broadcast applications can benefit from
the channel pop solo mode by allowing, for
example, the center channel to be highlighted while still maintaining some level on
the other channels. The amount of level increase—the “pop”—as well as the amount
of attenuation can be configured to meet
the needs of specific applications or users.
Two functions allow the input sources to
be checked for level or phase inconsistencies. The surround to stereo downmix
function is used to create a stereo signal
from the selected surround (5.1) source.
Key operating parameters in the surround
to stereo downmix function can be configured to meet the requirements of an application. This can be especially useful when
support for specific international broadcast
standards is required. 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 and stereo
monitor outputs. A configuration setting
allows the pre-fader surround monitor output to be selected for pre- or post-downmix
operation.
For flexibility, the StudioComm for Surround system is designed to easily integrate with equipment such as production
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intercom systems, on-air or recording tally
signals, and audio consoles. Two remotecontrol inputs provide access to the mute
all and dim 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 and stereo monitor
outputs.
Installation
In this section you will be installing the
Model 76DA Central Controller in an equipment rack. Connections to the digital audio
inputs, digital monitor outputs, and analog
monitor outputs will be made. A dedicated
digital audio timing reference signal can
be connected to the sync input. If desired,
external equipment will be interfaced to
the remote control inputs. A location will
be selected for the first Model 77 Control
Console and it will be connected to the
Model 76DA. AC mains power will be connected to the Model 76DA. For advanced
applications up to three additional Model
77 or Model 71 Control Console units can
be connected to the Model 76DA.
System Components
The main shipping carton contains one
each of the following: Model 76DA Central
Controller, Model 77 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 appropriate for destinations outside of North
America. Any additional Model 77 or
Model 71 Control Consoles will be
shipped in separate cartons.
Mounting the Model 76DA
The Model 76DA Central Controller requires one space (1U) in a standard 19inch (48.3 cm) equipment rack. Secure
the Model 76DA 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
77 Control Console. A cable is supplied
to connect the Model 76DA to the Model
77. 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 two 25-pin female
D-subminiature connector. All the connectors are located on the Model 76DA’s back
panel. Refer to Figure 2 for a detailed view
of these jacks and the connector.
Audio Inputs
Two surround (5.1) and three stereo digital
audio sources can be connected. All sources can be monitored using the pre- and
post-fader surround and post-fader stereo
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 one or both of the downmix functions.) Stereo input C is also routed to the
stereo input C direct monitor output.
The audio inputs support digital audio signals with a sampling rate of up to 192 kHz
and a word length (depth) of up to 24 bits.
It’s best if the connected signal sources
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maintain a common sample rate and timing reference. Having all signals “locked”
together helps to ensure proper handling
by the Model 76DA’s all-digital signal
control path.
There is, however, an exception worth
noting. Circuitry associated with stereo
input C has sample rate conversion (SRC)
capability, allowing virtually any digital
audio signal to be connected. A signal
connected to stereo input C can have an
independent sample rate and timing reference and still be monitored correctly. Refer
to the Technical Notes section of this guide
for a detailed review of the SRC capability.
Nine BNC jacks on the Model 76DA’s
back panel are used to interface with the
18 channels associated with the digital
audio signal sources; each BNC connector
carries two audio channels. The digital
audio inputs are intended for connection
with unbalanced digital audio sources that
are compatible with the AES3 standard. In
broadcast or post-production environments
these signals may also be referred to as
following the SMPTE 276M standard. This
signal type has a nominal impedance of 75
ohms with a nominal signal level of 1 Vpp.
As expected, these digital audio sources
should be provided in the form of coaxial
cables with BNC plugs attached.
Balanced AES3 digital audio signals
can also be used with the Model 76DA’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.
Digital Monitor Outputs
The 25-pin female D-subminiature connector labeled Digital Monitor Outputs
provides access to the Model 76DA’s 16
channels of digital audio monitor output:
pre-fader surround, post-fader surround,
post-fader stereo, and stereo input C
direct. The pre-fader surround digital
monitor output channels are intended
for connection to metering or monitoring
equipment that requires uninterrupted fulllevel signals.
The post-fader surround digital monitor
output channels are intended to connect to
a 5.1 loudspeaker system. The post-fader
stereo digital monitor output is provided to
support a separate set of stereo monitor
loudspeakers.
The stereo input C direct digital monitor
output is essentially a unity gain copy of
the signal connected to stereo input C.
However, the signal does pass through the
sample rate conversion (SRC) and input
delay circuitry. The impact made by these
functions will depend on the specific input
signal and the Model 76DA’s configuration
settings.
For flexibility the digital monitor outputs
are transformer-coupled and can be configured to act as balanced or unbalanced
AES3 digital audio sources. The digital
monitor outputs are configured in two
groups with separate choices available
for the pre-fader surround/stereo input C
direct group and post-fader surround/postfader stereo group. When a group is set for
balanced AES3 operation the signals have
a nominal impedance of 110 ohms and a
nominal level of 5 Vpp. Signals of this type
are normally interconnected using shielded
twisted-pair cable terminated with 3-pin
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XLR connectors. When a group is configured for unbalanced AES3 operation the
signals have a nominal impedance of 75
ohms and a nominal level of 1 Vpp. These
signals are typically interconnected using
coaxial cable terminated with BNC connectors. For details on how a Model 77 Control
Console is used to select the digital monitor output types refer to the Configuration
section of this user guide.
A cable assembly with a 25-pin male Dsub connector (DB-25M) 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 digital audio
signals this allows support for 16 audio
channels; eight interfaces each supplying
two audio channels.
A wiring assembly prepared for the Model
76DA’s digital monitor outputs, when configured for balanced AES3 (110 ohms/
5 Vpp), would be identical to that of a DA88-style output assembly. An assembly
of this type would have a 25-pin male Dsubminiature connector (DB-25M) on one
end and eight 3-pin male XLR connectors
on the other. A wiring assembly prepared
for the Model 76DA’s digital monitor outputs, when set for unbalanced AES3
(75 ohms/1 Vpp), would typically have
eight BNC plugs attached.
For compatibility with balanced AES3
digital audio signals connect the D-sub’s +
terminal as signal high and the – terminal
as signal low. In most applications a 3-pin
male XLR connector 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 unbalanced AES3
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 connectors 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 76DA’s
D-sub connectors use 4-40 threads. This
complies with the original design standard
for D-subminiature connectors.
Pre-Fader Surround Digital Monitor
Output
The pre-fader surround digital monitor
output channels are intended to connect
to metering, measurement, or other
signal monitoring equipment that requires
uninterrupted, full-level digital audio signal
sources.
Stereo Input C Direct Digital Monitor
Output
The stereo input C direct digital monitor
output is intended for use in site-specific
applications. It provides an uninterrupted,
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TASCAM® Signal Signal
Connections Channel High (+) Low (–) Shield
Pre-Fader L/R 1 24 12 25
Pre-Fader C/SUB 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/SUB 6 4 17 5
Post-Fader LS/RS 7 15 3 16
Post-Fader Stereo 8 1 14 2
Notes: 1) All signals transformer-coupled digital audio;
selectable for balanced or unbalanced AES3
compatibility.
2) Connector type on Model 76DA is 25-pin female
D-subminiature (DB-25F). Installer must provide male
(DB-25M). Connector uses 4-40 threaded inserts for
locking with mating plug.
3) Wiring scheme follows TASCAM DA-88 convention.
Standard DA-88-type wiring harnesses are directly
compatible, with the possible exception of 4-40 screw
threads being required.
Figure 4. Connections for Digital Monitor Outputs
full-level digital audio signal source that
is post-SRC and input delay in the signal
chain.
Post-Fader Surround Digital Monitor
Output
The post-fader surround digital monitor output channels are designed for connection
to digital inputs on audio amplifiers associated with monitor loudspeakers. Alternately,
they could be connected to the inputs of
loudspeakers that contain integrated amplifiers with digital audio input capability.
Post-Fader Stereo Digital Monitor
Output
The post-fader stereo digital monitor output
channels are intended to support a stereo
loudspeaker system, either by connecting
to the digital input of an amplifier associated with a set of loudspeakers or directly
to a set of amplified speakers that provide
digital inputs.
Analog Monitor Outputs
The connector labeled Analog Monitor
Outputs provides access to the Model
76DA’s 6-channel (5.1) surround and
2-channel stereo analog monitor outputs.
The surround analog monitor output channels are intended to connect to analog
inputs associated with the surround loudspeaker system incorporated in a facility.
The stereo analog monitor output allows
support for a secondary set of stereo monitor loudspeakers.
The analog monitor output channels are
designed for connection to audio amplifiers
associated with monitor loudspeakers or
to the inputs of loudspeakers that contain
integrated amplifiers. The analog monitor
outputs are electronically balanced and
will perform optimally when driving loads
of 2000 (2 k) ohms or greater. In most applications 3-pin male XLR connectors will
be used to interface with the inputs on the
associated amplifiers or amplified speakers.
In this case the + terminal would go to pin 2
of the XLR, the – terminal to XLR pin 3, and
the shield terminal to XLR pin 1.
Balanced operation of the analog monitor
outputs is the preferred connection method
but unbalanced operation does not pose a
problem. To connect to an unbalanced load
connect the + terminal as signal high, and
only the Model 76DA’s shield terminal as
the signal low/shield. Leave the – terminal
unconnected. For correct unbalanced
operation, it is important not to connect
– and shield together.
The wiring scheme used by the D-subminiature connector complies with that
made popular by TASCAM with their DA-88
product. A wiring assembly prepared for
the Model 76DA’s analog monitor outputs
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is identical to that of a DA-88-style output assembly. Please refer to Figure 5 for
the exact connection details. Again note
that unlike a DA-88-style assembly, the
Model 76DA’s D-sub connectors use 4-40
threads.
Signal Signal
Connections High (+) Low (–) Shield
Surround L 24 12 25
Surround R 10 23 11
Surround C 21 9 22
Surround SUB 7 20 8
Surround LS 18 6 19
Surround RS 4 17 5
Stereo L 15 3 16
Stereo R 1 14 2
Notes: 1) Connector type on Model 76DA is 25-pin female
D-subminiature (DB-25F). Installer must provide
male (DB-25M). Connector uses 4-40 threaded inserts
for locking with mating plug.
2) Wiring scheme follows TASCAM DA-88 convention.
Standard DA-88-type wiring harnesses are directly
compatible, with the exception of 4-40 screw threads
being required.
Figure 5. Connections for Analog Monitor
Outputs
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 signal but is generated
specifically as a timing reference signal.
Bi-level video sync signals were originally
provided to support NTSC and PAL broadcast applications, although they continue
to be used by contemporary equipment.
Tri-level sync signals were primarily associated with facilities that supported highdefinition (HD) video equipment, however
the importance of this type of sync seems
to be waning. Both bi-level and tri-level
signals can be found at numerous rate
combinations, configured to allow for compatibility with the various video formats.
Sync Input
The Model 76DA requires a timing reference (sync) signal so that the digital audio
input and digital monitor output signals will
be handled correctly. A configuration setting allows the source of sync to be the L/R
input of the currently selected surround
or stereo digital audio input. While this is
acceptable, audio artifacts (clicks or noise)
can occur when switching between inputs.
A better method is to connect a dedicated timing reference signal to the Model
76DA’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
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With the wide range of allowable sync
sources proper Model 76DA operation
should be easy to obtain. Extensive testing
has been done using many different sync
source types and rates. Interested users
can refer to Appendix B of this user guide
for details.
The external sync reference source is connected to the sync input BNC connector
located on the Model 76DA’s back panel.
For flexibility this input can be configured
to be high-impedance (“floating”) or terminated with an impedance of 75 ohms.
A sync source that is dedicated for use by
the Model 76DA’s sync input will typically
have input termination enabled. If the sync
for Surround
signal connected to the Model 76DA 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.
Remote Control Inputs
Support is provided for two remote control
input functions: remote mute all and remote dim. These functions only impact the
post-fader surround and stereo digital and
analog monitor outputs. The Model 76DA’s
inputs use logic gates, “pulled up” to 5 volts
DC by way of resistors, which are active
whenever they are brought to their logic
low state. Inputs of this type are commonly
referred to as GPI inputs. While the input
circuitry is protected from over-current and
static discharge (ESD), 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.
A 9-pin female D-subminiature connector
is used for the remote control inputs. Refer
to Figure 6 or Appendix A for the exact
connection details. Note that pin 4 (remote
common) connects to the Model 76DA’s
internal circuit common connection as well
as to the Model 76DA’s chassis and mains
earth connections. Figure 6 also shows
two spare remote control inputs (pins 8
and 9). These are provided for future applications and should remain unconnected.
This connector also allows access to an
RS-485 data interface. This interface is
not supported in the Model 76DA and, as
such, pins 7 and 2 should remain unterminated.
Signal Pin Direction
Data + (RS-485/RS-422) 7 Not used
Data – (RS-485/RS-422) 2 Not used
Data Shield 1 Shield
Remote Mute All 5 Input
Remote Dim 6 Input
Remote Spare 1 8 Input
Remote Spare 2 9 Input
Remote Common 4 Common
Note: Connector type on Model 76D
D-subminiature (DE-9F). Connector uses 4-40
threaded inserts for locking with mating plug.
Figure 6. Connections for Remote Control
Inputs
A is 9-pin female
Connecting the Model 76DA
to the Model 77
A 9-pin female D-subminiature connector,
labeled To/From Control Consoles, is provided on the back panel of the Model 76DA
Central Controller. This is used to interface
the unit with Model 77 Control Consoles.
Refer to Figure 7 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 77 Control
Console. A cable with 9-pin male D-sub
(DE-9M) connectors on each end is
used to interconnect the Model 76DA with
the Model 77 units. A cable is included in
the shipping carton. The cable implements
all nine connector pins in a one-to-one
manner.
Should an interconnecting cable of a different length be required there’s no problem
for one to be fabricated and used. While it
can be wired in a one-to-one fashion supporting all nine pins, only four connections
are required: pin 1 (data +), pin 6 (data –),
pin 4 (DC +), and pin 9 (DC –). The Model
76DA’s connector pin-out scheme was de-
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Signal Pin Direction
Data + (RS-485) 1 To/From Models 77/71
Data – (RS-485) 6 To/From Models 77/71
Data Shield 2 To/From Models 77/71
DC + (12 V) 4 To Models 77/71
DC – (12 V Return) 9 To Models 77/71
DC Power Shield 5 To/From Models 77/71
Note: Connector type on Model 76DA is 9-pin female
D-subminiature (DE-9F). Connector uses 4-40
threaded inserts for locking with mating plug.
Figure 7. Connections between Model 76DA and
Model 77 and Model 71
signed 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.
A few simple calculations are required to
determine the maximum cable length when
connecting a Model 76DA to a Model 77.
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
76DA to a Model 77. The Model 76DA supplies 12 volts DC with a maximum current
of 500 milliamperes.
The Model 77 requires a minimum of
9 volts DC, 100 milliamperes, for correct
operation. (The voltage must be measured
directly at the Model 77’s 9-pin connector.)
So the maximum interconnecting cable
length is directly related to the resistive
voltage losses associated with the two DCcarrying conductors. As the Model 76DA
supplies 12 volts and the Model 77 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 77’s
required current in amperes). Remember to
include the resistance in both the DC + and
DC – wires when calculating the voltage
drop. If it’s greater than 3 volts your cable
is too long or the wire gauge is too small.
Additional Control Consoles
Some installations may benefit from the
Model 76DA’s ability to be controlled by
additional control consoles. At least one
Model 77 Control Console must be connected to the Model 76DA Central Controller. After this requirement has been met up
to three additional Model 77 or Model 71
Control Consoles can also be connected
and to powered by the Model 76DA.
When connecting multiple control consoles
to a Model 76DA all nine pins of each
interconnecting cable can be connected in
parallel (“multed”). Using this arrangement
the data and 12 volts DC power signals between all the units will be multed. A custom
cable implementation requires just four pins
to be connected: pin 1 (data +), pin 6 (data
–), pin 4 (DC +), and pin 9 (DC –).
To make installation simple, a “bus” cable
assembly can be created using a short
length of ribbon cable with one male and
multiple 9-pin female D-subminiature insulation-displacement connectors attached.
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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 76DA to Model 77 cable length are
discussed. Note the required current for
a Model 77 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 77 units.
AC Mains Power
The Model 76DA operates directly from AC
mains power of 100 to 230 volts, 50/60 Hz.
Being a “universal input” device, there are
no switches to set or jumpers to install to
match a location’s mains voltage. The unit
uses a 3-pin IEC 320 C14-type inlet connector to mate with a detachable mains
cord. All units are supplied with a mains
cord that has a North-American-standard
plug (NEMA 5-15L) on one end and an 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 Wire Color
Neutral (N) Light Blue
Line (L) Brown
Protective Earth (E) Green/Yellow
Safety Warning: The Model 76DA
does not contain an AC mains disconnect s
witch; 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 76DA will perform a power-up sequence. The two LEDs on the right side
of the front panel will individually light in a
rapid right-to-left test sequence. Then the
LEDs will flash in cadence while the firmware loads into the Model 76DA’s main
logic device. After just a few seconds initial
system operation will commence and the
two LEDs will perform their intended functions. Once operating data is being interchanged with the one or more connected
Model 77 or Model 71 Control Consoles
the control console status LED will also
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 77 units will go through
a power-up sequence, lighting each of its
LEDs in succession. Using its 4-digit display, each Model 77 will then momentarily
display its address, its software version, and
the main and logic device software versions
of the associated Model 76DA.
All connected Model 71 units will also go
through a power-up sequence after mains
power is applied to the Model 76DA. Each
of the Model 71’s three LEDs will light
momentarily. After these LEDs have been
lit, the device address will be shown briefly
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using the dim and reference level LEDs,
as shown in Figure 8 in the Configuration
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 76DA. If the Model
71’s status LED does not light check to see
if there is a device address conflict among
all connected control consoles and that all
cables are connected properly.
Should an error be detected during the
start-up process the two LEDs on the Model
76DA’s front panel will continue to flash in
cadence indefinitely. On the Model 77 units
a diagnostic code may be displayed. Refer
to the Technical Notes section of this user
guide for details.
Only after the Model 76DA and all connected Model 77 and Model 71 units have
correctly powered up will full system operation begin. It’s possible that audio signals
will first be present on the digital monitor
outputs. The analog monitor outputs will
only become active after a protection interval has elapsed. These outputs are muted
using electro-mechanical relays that operate under software control.
using a Model 77 Control Console. However,
two configuration choices are 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 77 Control Console is used to
display and select the desired system configuration. Here’s an overview of what can
be configured:
• Model 77 Device Address (must be
unique for each unit!)
• Stereo Input C Sample Rate Converter
• Post-Fader Stereo Digital and Analog
Monitor Output
• Bass Management
• Mute/Solo Bass Management Mode
• Sync Source
• Sync Input Termination
• Audio-Synced-to-Video Sample Rate
• Digital Monitor Output Types
• Reference Level
• Overall Display Mode
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
76DA Central Controller. Other parameters
affect how the one or more Model 77 Control Consoles will display status conditions
and respond to user commands. Most
of the configuration choices will be made
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• Reference Level in dB SPL
• Auto Reference Level Off
• Dim Level
• Remote Inputs
• Surround to Stereo Downmix Levels
• Pre-Fader Surround Digital Monitor
Output Mode
• Channel Pop Solo Mode Offset Levels
• Input Delay A and B
• Post-Fader Digital and Analog Monitor
Output Channel Level Offsets
for Surround
The configuration diagrams, located later
in this section, give details on setting each
parameter. An overview of each configurable parameter is provided in the following
paragraphs.
Entering and Exiting the
Configuration Mode
A small button is located on the back of
each Model 77 Control Console, adjacent
to its 9-pin female D-sub connector. On any
connected Model 77 pressing and holding
this button for two seconds places both this
specific unit and the Model 76DA into their
configuration modes. Other connected Model 77 and Model 71 units will enter a standby mode. When the Model 76DA enters its
configuration mode it will immediately mute
the monitor outputs as a speaker protection measure. When a Model 77 enters the
configuration mode its array of buttons and
LEDs no longer perform their normal functions, instead they are used to display the
operating parameters and reflect configuration changes as they are made.
As a user aid, a Model 77 that has entered
the configuration mode will have its mute
and solo LEDs (associated with the channel mute/solo section) light in an alternating
manner. Other connected Model 77 units
will indicate that they have entered the
standby mode by simultaneously flashing
their mute and solo LEDs.
To leave the configuration mode and return
the system to normal operation requires
one last action to be made on the Model 77
unit that’s in its configuration mode; press
and hold its configure the button for two
seconds. Note that configuration changes
are stored in nonvolatile memory only after
the configuration mode has been exited.
Our apologies to those of you who find the
configuration 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
77 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 76DA
Central Controller as well as the Model 77
and Model 71 Control Consoles. The individual device address is stored in each
Model 77. The device address and button
configuration parameters are stored in the
Model 71. All other configuration parameters are stored in the Model 76DA.
Model 77 Device Address
A unique device address must be assigned
to each Model 77 that is connected to a
Model 76DA. The choices are A1, A2, A3,
or A4, with the default address being A1. As
most installations will find only one Model
77 utilized, its default setting is appropriate. For installations that use a second,
third, or fourth Model 77 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 77 unit. All other settings
can be made on any one of the connected
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Model 77 units. Be sure that any selected
address does not conflict with addresses to
be assigned to Model 71 units.
Stereo Input C Sample Rate
Converter
Circuitry associated with stereo input C can
provide sample rate conversion (SRC) for
digital audio signals connected to that input.
The acceptable input range for sample rate
conversion is very wide, but is dependent
upon the output sample rate. With an output sample rate of 48 kHz any signal with
a sample rate over a range of 8 to 216 kHz
can be properly monitored by the system.
This capability can be especially useful with
signals that are not synchronized with respect to the others connected to the Model
76DA, even if the sample rate is identical. The only compromise is that the SRC
process adds a fixed input-to-output (group)
delay of approximately 1 millisecond, a value that shouldn’t impact most installations.
As such, it’s recommended that the sample
rate converter remain enabled. However
there might be special cases where this resource isn’t desired and it can be disabled.
Post-Fader Stereo Digital and
Analog Monitor Outputs
In addition to the post-fader surround digital and analog monitor outputs, separate
post-fader stereo digital and analog monitor
outputs are also provided. By default the
stereo outputs can be enabled by an operator. In applications where stereo monitor
loudspeakers are not connected to either of
the post-fader stereo monitor outputs, the
outputs can be disabled. This can minimize
confusion, preventing an operator from
attempting to select the post-fader stereo
digital and analog monitor outputs.
Bass Management
The Model 76DA incorporates flexible and
sonically excellent bass management capabilities which can impact both the digital
and analog post-fader monitor outputs. It
is, however, limited to functioning only at
sample rates of 44.1, 48, 88.2, and 96 kHz.
Five configuration parameters are used to
enable or disable bass management as
well as to select the characteristics of the
associated audio filters. While the settings
are simple to make, great care must be
taken in first reviewing the entire monitor
system. Only after a full understanding of
the performance of the associated surround and, if present, stereo loudspeaker
systems are determined can a plan for
bass management be established.
Bass management can be enabled so that
the function is active when the surround
post-fader monitor outputs are enabled. It
can also be independently enabled so that
it can be active when the stereo post-fader
monitor outputs are enabled. By default
bass management for both outputs is
disabled. The crossover point of the bass
management filters can be selected from
among four choices: 40, 50, 60, or 80 Hz.
The slope of the low-pass and high-pass
filters associated with bass management
can be independently selected. The choices are 12 dB/octave or 24 dB/octave with
the latter being the default.
Mute/Solo Bass Management
Mode
The Model 76DA’s mute/solo function can
be configured for how it performs in applications where bass management has been
enabled. This is a somewhat-esoteric topic
but can be important in certain situations.
The default setting for the mute/solo bass
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management mode is for pre-bass management. This means that if a channel has
been selected for, as an example, soloing
then the bass management filters will send
any applicable low-frequency content to
the post-fader digital and analog subwoofer outputs. So in this case the solo function
is really an “input channel” solo since the
actual acoustical energy associated with
that channel will be reproduced by both the
main channel and subwoofer loudspeakers. So while one is “soloing” a channel (or
set of channels) two or more loudspeakers
may be reproducing the signals.
The mute/solos bass management mode
can also be set for post-bass management. When this mode is enabled a channel selected for soloing will cause only its
associated post-fader digital and analog
monitor output channels to remain active. So if, for example, one of the main
surround input channels (one of the “5.”
channels) is selected for soloing then all
post-fader output channels except that one
will mute. The bass management filters
will remain enabled, thus sending only the
high-passed audio energy from the soloed
input channel to the soloed output channel.
Only if the LFE channel has been selected
for soloing will the subwoofer output remain active. Typically the only reason why
the post-bass management mode would
be selected is when troubleshooting issues
with the loudspeaker system.
Sync Source
The Model 76DA 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.
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 76DA 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 76DA’s timing reference
the sample rate of the connected digital
audio signals must be specified. In most
cases the default value of 48 kHz will be
appropriate, but rates from 32 to 192 kHz
are available.
Pre-Fader Surround/Stereo
Input C Direct Digital Monitor
Output Type
To meet the needs of specific installations
the nominal impedance and level characteristic of the pre-fader surround and stereo
input C direct digital monitor outputs can
be selected. They are selected as a group;
configuration of individual digital outputs is
not provided. If the digital output signals are
going to be connected to balanced AES3
inputs then the setting that provides
a source impedance of 110 ohms and
a nominal 5 Vpp output level would be
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appropriate. If the digital output signals are
going to be connected to unbalanced AES3
inputs then the setting that provides a 75
ohm source impedance and a nominal output level of 1 Vpp would be correct.
Post-Fader Surround/Stereo
Digital Monitor Output Type
The source impedance and output level of
the post-fader surround and stereo digital
monitor outputs, as a group, can be configured. The information previously provided
concerning configuring the pre-fader surround/stereo input C direct digital monitor
output type also applies to these outputs.
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 post-fader
surround digital and analog monitor output
level to be stored, and then enabled by
pressing the Model 77 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, and downmix
functions are not active. The remote
mute all and remote dim functions must
also not be active.
3. Use the Model 77 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 77’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 77’s back panel.
6. Once the configuration mode has been
entered, all the monitor outputs (digital
and analog) will mute. Press and hold
the reference level button; its associated LED will begin to flash. After five
seconds the LED will light steadily to
indicate that a “snapshot” of the new
reference level has been taken. The
Model 77’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.
7. To complete the process the configuration mode must be exited. This is performed by again pressing and holding
the configuration button for two seconds. The new reference level is now
stored in the Model 76DA’s nonvolatile
memory. Only by repeating the entire
procedure can the value be changed.
Once the configuration mode has been
exited, the digital and analog monitor outputs will again become active. Confirm
that the correct level has been stored by
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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 77’s 4-digit numeric display can
be configured to display the post-fader surround and stereo digital and analog monitor output levels 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 turned 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 pressure level (SPL). It is used in
conjunction with the reference level in dB
SPL configuration and the stored reference
level. The 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 post-fader
surround or stereo digital and analog
monitor outputs are at their reference level,
either through activating the reference level
function or manually adjusting the rotary
level control, the Model 77’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.
Auto Reference Level Off
When auto reference level off is enabled,
the function automatically turns the reference level function off if a change is made
to the rotary level control while the reference level function is active.
Dim Level
The dim function is used to reduce the
post-fader surround and stereo digital and
analog monitor output levels by a preset
amount. The reduction is in dB relative to
the post-fader surround and stereo monitor
outputs’ current level. There are four dim
level values available: –10.0, –15.0, –20.0,
and –25.0 dB.
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Remote Mute All
Two configuration choices are associated
with the remote mute all function: disabled
and enabled. To utilize the remote mute all
function simply requires you to select the
enabled setting.
Remote Dim
Two configuration choices are associated
with the remote dim function: disabled and
enabled. To utilize the remote dim function
simply configure it for enabled.
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 time delay applies to all input
signals and cannot be applied selectively.
A 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
77 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.
For operating flexibility two different input
delay values can be selected and stored
during the configuration process. These
can then be enabled as required by the
operator during normal system operation.
The default value for both Delay A and
Delay B is 0 milliseconds. Typical applications would require only one input delay
to be configured. But in other cases two
different, both non-zero, input delay values
will be selected. This could be appropriate
in applications where multiple video display
systems are being used in the same control room or monitoring facility. Each video
display may exhibit its own processing
latency and audio would need to be “lined
up” accordingly. During normal StudioComm
operation an operator can select the appropriate input delay for the display system
currently being utilized.
Surround to Stereo Downmix
Levels
The surround to stereo downmix function is
a useful tool for checking the compatibility
of surround (5.1) input signals with stereo
and monaural playback environments. The
exact technical formula for how the Model
76DA handles the surround to stereo downmix function can be selected by way of four
configurable parameters. The default settings create a good general-purpose function that’s effectively used by numerous
users of Studio Technologies’ StudioComm
for Surround products. But there are application-specific situations where modifying one or more of the parameters will be
appropriate. This can be in response to a
personal choice in monitoring methods or,
more frequently, to meet the requirements
of international broadcast standards.
When the surround to stereo downmix
function is active the path from the left (L)
channel input to the left post-fader output
channel and the right (R) channel input to
the right post-fader output channel is maintained. A configuration choice allows the
level of the L and R inputs routed to the
L and R outputs to be selected. By default,
when the surround to stereo downmix function is active the level of the L and R inputs
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remain at unity, with no gain or loss applied.
An alternate setting allows the level of L
and R input channels to be reduced (attenuated) by 3 dB. (The available changes
in signal level can also be notated as 0 dB
or –3 dB.)
When the surround to stereo downmix
function is active the left surround (LS)
input is routed to the left (L) post-fader
monitor output; the right surround (RS)
input is routed to the right (R) post-fader
monitor output. By default the level of the
LS and RS signals routed to L and R will be
reduced (attenuated) by 3 dB. An alternate
setting allows the levels to be reduced by
6 dB. (These settings can also be notated
as –3 dB and –6 dB.)
When the surround to stereo downmix function is active the center (C) input is routed
to both the left (L) and right (R) post-fader
monitor outputs. By default the level of the
C signal routed to L and R will be reduced
(attenuated) by 6 dB. An alternate setting
allows the attenuation level to be 3 dB.
(These levels can also be notated as –3 dB
and –6 dB.)
By default, when the surround to stereo
downmix function is active the LFE channel
associated with a surround input is fully
attenuated (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 reduced by 6 dB and routed to both the left
(L) and right (R) post-fader monitor outputs.
A last word on configuring the surround
to stereo downmix function: no matter
what choices are made when the function
is active the center (C), left surround (LS),
right surround (RS), and subwoofer (SUB)
post-fader monitor outputs will fully mute.
Pre-Fader Surround Digital
Monitor Output Mode
The pre-fader surround digital monitor output can be configured as to its place in the
Model 76DA’s signal flow. The choices are
pre- or post-downmix. In the pre-downmix
mode the digital monitor output channels
will not be impacted by the state of the
downmix functions. This setting would be
appropriate if the pre-fader surround digital monitor outputs were being routed to a
storage system, routed to another facility,
etc. In this case the action of an operator
enabling or disabling the downmix functions won’t impact the pre-fader surround
digital monitor output signals. If the postdownmix mode is selected the pre-fader
surround digital monitor outputs will reflect
the actions of the downmix functions. This
choice would be correct if, for example, level meters were connected to the pre-fader
surround digital monitor outputs. In this
scenario an operator would want to visually observe the actions that the downmix
functions impart on the signals.
Channel Pop Solo Mode
Offset Levels
Two parameters can be configured that
determine how the channel pop solo function will impact the output levels of the
post-fader digital and analog monitor outputs. The up offset level sets the amount
of increase (gain) that a channel will experience when it is soloed in the channel pop
solo mode. The down offset level sets the
amount of decrease (attenuation) that the
non-soloed channels will experience when
a channel is active in the channel pop solo
mode.
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Post-Fader Digital and Analog
Monitor Output Level Offsets
To provide assistance during room calibration, the relative output levels of the
post-fader surround and stereo digital and
analog monitor output channels can be adjusted over a limited range. The eight channels can be adjusted in 0.5-dB steps over
a ±12-dB range. During configuration the
displayed value represents the dB level difference as compared to the nominal output
level. In most cases one surround and one
stereo channel should serve as the overall
reference level and not be changed. This
is typically the center channel for surround
and the left channel for stereo. The configured output level offset values apply to
both the digital and analog surround stereo
monitor outputs. It is not possible to configure a specific channel’s digital and analog
monitor output level offsets to independent
values.
This feature is provided primarily for use
when the post-fader monitor output channels are connected to loudspeaker systems that don’t offer a means of “trimming”
the input sensitivity of individual channels.
Without this capability, minor adjustments
to the output level of specific loudspeakers
to account for room acoustics wouldn’t be
possible.
It’s also possible to use the StudioComm’s
output level offset capability to adjust the
overall post-fader monitor output levels to
allow matching to the input sensitivity of
loudspeaker systems. In this case all the
channels (six for surround, two for stereo)
would be configured to have the same
output level offset setting. For example, the
six surround channels could all be configured to have a –3.5 dB output level offset.
However, great care must be taken when
configuring a system in this manner. The
dynamic range or noise floor of the audio
signals will be impacted and extreme settings could lead to poor monitor system
performance.
Restore Factory Defaults
The restore factory defaults function is provided primarily for factory use. In this way
a system can be shipped with the default
settings selected. While you are welcome
to use this function, be careful so that your
configuration efforts aren’t wasted. Specifically, be aware that the reference level
is reset to minimum level. All the other
parameters are fairly easy to set up, but
resetting the reference level would require
getting out an SPL meter and a calibrated
signal source. This is a hassle you may not
need!
Model 71 Control Console
Configuration
Two configuration choices are available on
each Model 71. One is its device address,
the other is the button disable mode. A
small button is located on the back of each
Model 71 Control Console, adjacent to the
9-pin female D-sub connector. Pressing
and holding this button for two seconds
places this specific unit in its configuration
mode; normal operation of the Model 76DA
and other connected Model 71 and Model
77 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. Refer to Figure 8 for details.
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Figure 8. Model 71 Control Console Front and
Back Panels
Device Address
The dim and reference level LEDs will
display the Model 71’s current device
address. The rotary level control is used
to select the desired device address; the
LEDs will respond accordingly. The device
address must be selected so as not to conflict with the device address of any other
connected Model 71 or Model 77 Control
Console. The choices are A1, A2, A3,
and A4. All Model 71 units have a default
device address of A4; Model 77’s units
have a default device address of A1. This
ensures that, in most cases, no change
will have to be made. Refer to Figure 9 for
details.
Address Dim LED Reference Level LED
A1 OFF OFF
A2 OFF ON
A3 ON OFF
A4 ON ON
Figure 9. Model 71 Device Address Chart
Button Disable
To disable the Model 71’s buttons, simultaneously press and hold both the dim and
erence buttons for two seconds. When
ref
the disable request has been recognized
the LEDs above both buttons will flash
rapidly. Release the buttons and they will
no longer enable or disable their normal
functions. To return the buttons to normal
operation simultaneously press and hold
both buttons for two seconds at which time
the two LEDs will flash rapidly.
To leave the configuration mode and return
a Model 71 to normal operation requires
one last action: again press and hold its
configuration button for two seconds. The
selected configuration parameters will be
stored in a nonvolatile memory device that
is located inside this specific Model 71.
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Configuration—Entering and Exiting Configuration Mode
Press and hold the configuration
button for 2 seconds to enter or
exit the configuration mode.
These LEDs will light alternately
when configuration mode is active.
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Configuration—Model 77 Device Address, Stereo Input C
Sample Rate Converter, and Post-Fader Stereo Digital and
Analog Monitor Output
Press and hold the Mute/Solo button
to display and configure the Model 77’s
device address, stereo input C sample
rate converter, and post-fader stereo
digital and analog monitor output.
This LED displays the configuration of the
stereo input C sample rate converter
(SRC).
LED not lit means SRC is disabled;
LED lit means SRC enabled. Use the button
to change the configuration.
These LEDs display the status of the post-fader stereo digital and analog monitor output function. When
LED Surround is lit the function cannot be enabled.
When LED Stereo is lit the function can be enabled.
Use the button to change the configuration.
Default: Device address A1.
Stereo input C sample rate converter enabled.
Post-fader stereo digital and analog monitor output can be enabled.
Note:The Model 77’s device address is the only parameter stored in the Model 77. All other parameters are stored in the Model 76DA.
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Use the Level control to change
this specific Model 77’s device address. Address can be either
A1, A2, A3, or A4. See Note below.
for Surround
Configuration—Bass Management and Mute/Solo Bass
Management Mode
Use these
buttons to select
bass management low-pass
filter slope.
LED Surround A
lit means
24 dB/octave;
LED Surround B
lit means
12 dB/octave.
Use these
buttons to
select bass
management
high-pass
filter slope.
LED Stereo A
lit means
24 dB/octave;
LED Stereo B
lit means
12 dB/octave.
This LED displays the configuration of
the surround output bass management.
LED lit means surround output bass
management enabled; LED not lit means
surround output bass management
disabled. Use the button to change
the configuration. See Note below.
Press and hold the Stereo C b
to display and configure the bass
management and mute/solo bass
management mode settings.
utton
This LED displays the configuration of
the stereo output bass management.
LED lit means stereo output bass
management enab
means stereo output bass management
disabled. Use the button to change
the configuration. See Note below.
Use the Level control to select the
bass management crossover
frequency. Choices are 40, 50,
60, or 80 Hz.
led; LED not lit
This LED displays
the configuration
of the mute/solo
bass mana
ment mode. LED
lit means mute/
solo functions
occur post-bass
management;
LED not lit means
mute/solo functions occur prebass management.
Use the button
to change the
configuration.
Bass management crossover frequency 80 Hz.
Mute/solo pre-bass management mode.
Note:Bass management capability only available at sample rates of 44.1, 48, 88.2, and 96 kHz.
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Configuration—Sync Source, Sync Input Termination,
Audio-Synced-to-Video Sample Rate, and Digital Monitor
Output Types
Use the Channel Solo LS and RS
buttons to select the post-fader
surround/stereo digital monitor
output type. Use the buttons to
change the configuration. LS LED
lit means unbalanced AES3 (75
ohms/1 Vpp); RS LED lit means
balanced AES3 (110 ohms/5 Vpp).
This LED displays the configuration
of the sync input termination. LED
not lit means sync input is not terminated; LED lit means terminated with
75 ohms. Use the button to change
the configuration.
Use the Channel Solo C and LFE buttons to
select the pre-fader surround/stereo input C direct digital monitor output type. Use
the buttons to change the configuration.
C LED lit means unbalanced AES3 (75
ohms/1 Vpp); LFE LED lit means balanced
AES3 (110 ohms/5 Vpp).
Press and hold
Use these buttons
to select the sync source.
LED Surround B
lit means sync
input, video;
LED Stereo A lit
means sync input,
DARS;
LED Stereo B lit
means sync input,
word clock;
LED Stereo C
lit means L/R of
currently selected
input.
the Stereo to
Mono button
to display and
select the sync
source, sync input termination,
audio-syncedto-video-sample
rate, and digital
monitor output
types.
Use the level control to adjust the audio-synced-to-video sample rate. Available
sample rates are 32, 44.1, 48, 88.2, 96,
176.4, and 192 kHz.
Default: Sync source is L/R of currently selected input.
Sync input terminated.
Audio-synced-to-video sample rate 48 kHz.
Pre-fader surround/stereo input C direct digital monitor output type balanced AES3 (110 ohms/5 Vpp).
Post-fader surround/stereo digital monitor output type balanced AES3 (110 ohms/5 Vpp).
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Configuration—Reference Level
Press and hold the Reference Level button for 5 seconds to take a “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 steadily when the “snapshot” has been taken. See Note below.
Default: Reference level set for –60.0 dB post-fader monitor output level.
Note: The 5-second button-press 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.
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Configuration—Overall Display Mode, Reference Level
in dB SPL, and Auto Reference Level Off
When the Mute All button is pressed, use the Channel Mute/Solo
L and R buttons to select the overall display mode. LED L lit
means attenuation mode is selected; LED R lit means SPL mode
is selected. Use the buttons to change the configuration.
When the Mute
All button is
pressed, use the
Reference Level
button to enable
or disable auto
reference level
off. When the
Reference Level
LED is lit auto
reference level
off is enabled.
Press and hold the Mute All b
Default: Attenuation display mode selected.
85.0 dB SPL reference level.
Auto ref level off disabled.
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y and set the overall display mode,
displa
the reference level in dB SPL, and auto
reference level off.
utton to
When the Mute All button is pressed,
use the Level control to adjust the
reference level in dB SPL.
for Surround
Configuration—Dim Level, Remote Mute All, and Remote Dim
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.
Use these buttons
to select dim level.
LED Surround B lit
means –10 dB;
LED Stereo A lit
means –15 dB;
LED Stereo B lit
means –20 dB;
LED Stereo C lit
means –25 dB.
This LED displays the configuration
of remote dim. LED not lit means
remote dim is disab
means enabled. Use the button to
change the configuration.
led; LED lit
Press and hold the Dim button to
display and select the dim level,
remote mute all, and remote dim.
Default: –20 dB dim level.
Remote dim enabled.
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Remote mute all enabled.
for Surround
Configuration—Surround to Stereo Downmix Levels and
Pre-Fader Surround Digital Monitor Output Mode
These LEDs display the configuration of the
pre-fader surround digital monitor output
mode. LED L lit means output channels are
pre-downmix; LED R lit means output channels are post-downmix. Use the buttons to
change the configuration.
Use these buttons
to select the level
change for the left
and right channels
when the surround
to stereo downmix
function is active.
LED Surround A
lit means 0 dB;
LED Surround B
lit means –3 dB.
Use these buttons
to select the level
change for the left
surround and right
surround channels
when the surround
to stereo downmix
function is active.
LED Stereo A
lit means –3 dB;
LED Stereo B
lit means –6 dB.
Use this button to select the
level change for the LFE
channel when the surround to stereo downmix function
is activ
e. LED not lit means
full attenuation; LED lit means
–6 dB.
Use these buttons to select
the level change for the
center channel when the
surround to stereo downmix function is active.
LED LS lit means –3 dB;
LED RS lit means –6 dB.
Press and hold
the Surround to
Stereo b
to display and
confirm the surround to stereo
downmix levels
and pre-fader
surround digital
monitor output
mode.
utton
Default: L and R channel level change 0 dB when surround to stereo downmix function active.
LS and RS channel level change –3 dB when surround to stereo downmix function active.
C channel level change –6 dB when surround to stereo downmix function active.
LFE level change full attenuation when surround to stereo downmix function active.
Pre-fader surround digital monitor outputs pre-downmix.
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Configuration—Channel Pop Solo Mode Offset Levels
Press and hold
the Surround A
b
utton to display
and select the
channel pop solo
up offset le
vel.
Press and hold
the Surround B
button to display
and select the
channel pop solo
down offset level.
Default: 6.0 dB channel pop solo up offset level.
–6.0 dB channel pop solo down offset level.
When the Surround A 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 Surround B button is pressed, use the level
control to adjust the channel pop solo down offset level.
ange is –0.0 to –12.0 in 0.5-dB steps and full mute.
The r
Full mute is selected by adjusting the level control past
–12.0, at which point the display will show – – – –.
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Configuration—Input Delay Settings
Press and hold the
Stereo A b
display and select
input delay A.
utton to
Press and hold the
Stereo B button to
display and select
input delay B.
Default: Input delay 0 ms for both A and B.
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.
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for Surround
Configuration—Post-Fader Digital and Analog Monitor Output
Level Offsets
Press and hold
utton
the L b
to configure
the surround L
level offset.
Press and hold both
the L and Surround/
Stereo buttons to
configure the stereo
L level offset.
Press and hold
both the R and
Surround/Stereo
buttons to configure
the stereo R level
offset.
Press and hold
the R button
to configure
the surround R
level offset.
Press and hold
the C button to
configure the
surround C
level offset.
Press and hold
the LFE button
to configure the
surround LFE
level offset.
Press and hold
the LS button to
configure the
surround LS
level offset.
Press and hold
the RS button
to configure the
surround RS
level offset.
Use the level control to adjust the post-fader digital and analog monitor output level offsets. The range is –12.0 to
12.0 in 0.5-dB steps.
Default: 0.0 dB post-fader surround monitor output level offsets.
0.0 dB post-fader stereo monitor output level offsets.
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Configuration—Restore Factory Defaults
Press and hold both the Surround/Stereo and Dim buttons for 5 seconds
to restore Model 77 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. See Note below.
Factory Defaults:
Device address A1.
Stereo input C sample rate converter enabled.
Post-fader stereo digital and analog monitor outputs can
be enabled.
Surround output bass management disabled.
Stereo output bass management disabled.
Bass management low-pass filter slope 24 dB/octave.
Bass management high-pass filter slope 24 dB/octave.
Bass management crossover frequency 80 Hz.
Mute/solo pre-bass management mode.
Sync source is L/R of currently selected input.
Sync input terminated.
Audio-synced-to-video sample rate 48 kHz.
Pre-fader surround/stereo input C direct digital monitor
output type balanced AES3 (110 ohms/5 Vpp).
Post-fader surround/stereo digital monitor output type
balanced AES3 (110 ohms/5 Vpp).
Reference level set for –60.0 dB post-fader monitor
output level.
Warning: Each Model 77 unit must have a unique address. Restoring factory defaults will reset only this specific
Model 77 to device 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.
Attenuation display mode selected.
85.0 dB SPL ref
Auto reference level off disabled.
–20 dB dim level.
Remote mute all enabled.
Remote dim enabled.
L and R channel level change 0 dB when surround to
stereo downmix function active.
LS and RS channel level change –3 dB when surround to
stereo downmix function active.
C channel level change –6 dB when surround to stereo
downmix function active.
LFE level change full attenuation when surround to stereo
downmix function active.
Pre-fader surround digital monitor outputs pre-downmix.
6.0 dB channel pop solo up offset level.
–6.0 dB channel pop solo down offset level.
Input delay 0 ms for both A and B.
0.0 dB post-fader surround monitor output level offsets.
0.0 dB post-fader stereo monitor output level offsets.
erence level.
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Operation
Now that you’ve installed and configured
the system, you’re ready to go. You should
find operation very easy. However, taking
time to study this section of the guide may
prove valuable.
Upon power up the system will return to
the last operating condition, including the
selected source, downmix modes, etc. As
a precaution, however, the post-fader surround and stereo digital and analog monitor output levels will always return to their
minimum value. The rotary level control
or the reference level button must then be
used to return the system to the desired
monitor output level.
Model 76DA Central
or Model 71 Control Consoles that have
been connected. Two system functions can
also be controlled by means of the remote
control inputs.
Model 77 Control Console
To make things easy to describe, the Model 77’s operator functions are divided into
six main groups: input source selection,
downmix, monitor output general functions,
channel mute/solo, display and display
mode, and remote control inputs.
Any change made to any one Model 77
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.
Controller
The Model 76DA’s front panel contains two
LEDs. The control console status LED will
light whenever the Model 76DA is communicating with the one or more connected
Model 77 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 77
is in the configuration mode or when the
Model 77 is going through its power-up
sequence.
The sync status LED will light whenever
a valid timing reference signal is being
received by the Model 76DA. A flashing
sync status LED indicates that a valid sync
signal is not being received.
Control Consoles
StudioComm for Surround operation is
controlled using the up to four Model 77
Input Source Selection
To select an input source press one of the
five input source buttons. The corresponding LED will light to indicate that the input
has been selected. Typically, only one
source will be selected for monitoring at
any one time. However, input stereo C can
be selected by itself, or mixed (summed)
with one of the other four inputs. To accomplish this is easy: simply press and hold
input stereo C then press the button associated with the other desired input source.
The two corresponding LEDs will light.
Alternately, press and hold the first desired
input (other than input stereo C) and then
press the input stereo C button.
It’s possible (although unlikely) that selecting an input will result in the mute all
function being enabled and an Err3 message being displayed. This would indicate
a conflict between the sample rate of the
selected input source and the bass management function. (Operation of the bass
Model 76DA/77 User Guide Issue 9, May 2014
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management function requires the source
to have a sample rate of 44.1, 48, 88.2, or
96 kHz.) Selecting a source with a sample
rate of 44.1, 48, 88.2, or 96 kHz will resolve the issue and normal operation will
resume. Refer to the Technical Notes section of this guide for additional details.
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 and stereo digital and
analog monitor outputs. And, depending on
the selected configuration, they may also
impact the pre-fader surround digital monitor output.
A specific downmix function can only be
enabled when it is applicable for the currently selected input source. This means
that the surround to stereo downmix function can only be enabled when surround
input A or B is selected.
The Model 77 associates the state of
the downmix functions with the currently
selected input. For example, if surround
input A is the selected input source and
the surround to stereo downmix function
is enabled, this condition will be “remembered” when switching to one of the stereo
input sources. Upon returning to surround
input A, the surround to stereo downmix
function will again become active.
Surround to Stereo
When the surround 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 2channel 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 LtRt, is routed to the L and R post-fader
surround digital and analog monitor output
channels. Also, whenever the surround to
stereo downmix function is enabled the C,
LS, RS, and SUB digital and analog monitor output channels are muted. By utilizing
this downmix function phase relationships
and inter-channel level issues can be
quickly observed.
Stereo to Mono
The stereo to mono downmix function
combines the L and R audio channels to
create a single-channel monaural signal.
This signal is sent out the C surround
digital and analog monitor output channels
while the L, R, LS, RS, and SUB digital
and analog monitor output channels are
muted.
When a surround source has been selected for monitoring, the surround to stereo
downmix function will automatically enable
whenever the stereo to mono downmix
function is enabled. This ensures that an
operator will hear a mono signal created
by folding down all channels associated
with the selected surround input.
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Monitor Output General
Functions
Four buttons and one rotary control are
associated with the post-fader digital and
analog surround and stereo monitor output
functions. The buttons control operation of
the surround and stereo outputs, reference
level, mute all, and dim functions. The rotary
level control is used to manually set the
post-fader surround and stereo digital and
analog monitor output levels. These buttons
and the rotary control do not impact the
pre-fader surround and stereo input C direct
digital monitor outputs.
Surround and Stereo Digital and Analog
Outputs
The surround/stereo function allows
selection between two different loudspeaker
systems. When the surround output is selected the six post-fader surround channels
associated with both the digital and analog
monitor outputs are active. The channels
associated with the post-fader digital and
analog stereo monitor outputs are muted.
When the stereo output is selected the
left (L) and right (R) channels associated
with both the post-fader digital and analog
stereo monitor outputs become active; the
six channels associated with the post-fader
surround digital and analog monitor outputs
mute.
Remember that the Model 77 Control Console can be configured to disable the surround/stereo button. If the button is pressed
and the post-fader stereo monitor outputs
are not selected, this must be the case!
Display Current Sample Rate
The surround/stereo monitor output select
button is also used to display the system’s
current sample rate value. Pressing and
holding the surround/stereo 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.
Reference Level
The reference level button sets the postfader surround and stereo digital and
analog monitor output levels to a preset
value. Technical personnel, using a soundpressure-level (SPL) meter and precision
signal source, should have set this level
to meet the requirements of the specific
monitoring environment. The LED associated with the reference level button will light
whenever the function is active. The 4-digit
display will indicate the reference output
level. Note that the system’s default reference level is –60.0 dB so “out of the box”
the Model 77 will display –60.0 when reference level mode is enabled.
How the rotary level control functions whenever the reference level mode is active
depends on a configuration setting. If the
auto reference level off function is disabled
turning the rotary level control will have no
impact on the reference level function; it will
remain active. If the auto reference level
off function has been enabled turning the
rotary level control will cause the reference
level function to automatically turn off.
The LED associated with the reference
level button can also serve as a calibration
aid. If the reference level mode is not active,
whenever the post-fader surround or stereo
digital and analog monitor output levels are
precisely the same as that stored for the
reference value the reference level LED
will flash. This exact level can be reached
through the use of the rotary level control,
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for Surround
either by itself or through the setting of the
rotary level control in conjunction with the
dim function. Whatever path the post-fader
surround and stereo monitor outputs take
to reach the reference level value, it will
cause the reference level LED to flash!
Mute All
Pressing the mute all button causes the
output channels associated with the postfader surround and stereo monitor outputs
to mute. The 4-digit display indicates the
mute condition by showing four dashes
(– – – –). The mute all button is always set
to “latch” the function on and off. The LED
associated with the mute all button will light
whenever mute all is active. Note that if
mute all is enabled via the remote mute all
function, the mute all LED will flash.
Dim
The dim function is provided for user
convenience, allowing the post-fader surround and stereo digital and analog monitor output levels to be reduced by a fixed
amount. The Model 77’s configuration
mode allows the dim level to be selected
from among four choices: –10.0, –15.0,
–20.0, or –25.0 dB. Pressing the dim button will enable the function. The dim button
is always set to “latch” the function on and
off. The 4-digit display, when selected for
output level mode, will indicate the revised
post-fader monitor output level. If the requested “dimmed” output level is equal to or
less than –96.0 dB, the monitor outputs will
go into full mute and the display will show
four dashes (– – – –). When dim is active
the post-fader monitor output level reduction will apply no matter whether the level
is being set by the rotary level control or by
the reference level button. The LED associated with the dim button will light whenever
dim is active. If dim mode is enabled via the
remote dim function the dim LED will flash.
It’s worth using a few sentences to discuss the auto dim off function. Whenever
dim is enabled due to the dim button being pressed, and the rotary level control is
active (reference level mode is not active),
changing the setting of the rotary level
control will automatically turn off dim. The
auto dim off function is a unique attempt
at protecting the aural health of users. No
longer will there be a heart-stopping blast of
audio when the dim button is pressed, supposedly to enable dim, but actually turning
dim off because it was already enabled. It’s
hard to explain unless you’ve experienced
this in person—trust us, this situation can
and does happen!
Note that the auto dim off function is not
active whenever dim is enabled due to
the remote dim function being active. This
allows remote control equipment, such as a
talkback system, to reliably dim the monitor
outputs.
Rotary Level Control
The rotary level control is used to manually
adjust the post-fader surround and stereo
monitor output levels. The level control
provides the ability to adjust the post-fader
surround and stereo digital and analog
monitor output levels over a 70-dB range.
Technically the rotary level control is a 24step-per-revolution mechanical encoder.
The amount of level change in dB per step
(“click”) will depend on how quickly the
control is turned. When rotated slowly, each
step represents a 0.5-dB change in level. In
this case, to traverse the entire level range
would require rotating the control more than
five full turns. But the Model 77’s software
detects when the control is rotated more
quickly and increases the amount of level
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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 post-fader
monitor 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 and stereo monitor output channels will automatically mute. As previously
discussed, the 4-digit display indicates the
mute condition by showing four dashes
(– – – –).
If the mute all function is active the rotary
level control won’t have an impact on the
post-fader surround and stereo output levels. It’s also not active whenever the reference level function is active, except if the
auto reference level off function has been
enabled.
Channel Mute/Solo
The channel mute/solo functions allow
specific channels to be selected for individual or group mute or “solo” monitoring.
The functions impact the post-fader surround and stereo monitor outputs, taking
place electrically “after” the input source
selection, input delay, downmix, and level
control functions. The relationship between
the mute/solo function and the bass management resources will depend on how the
system has been configured.
The mute/solo mode button and the six
channel mute/solo buttons, along with associated LEDs, work together to provide
excellent operating flexibility. The channel
mute/solo mode button allows the operator
to select between the mute and solo functions. Going from mute mode to solo mode,
or vice-versa, clears all active mutes or
solos. Pressing the mode button twice is
a legitimate means of quickly clearing
muted or soloed channels. To mute or solo
a channel simply requires pressing one
of the channel mute/solo buttons. The buttons function in a press-to-enable/press-todisable “latching” mode. Multiple channels
can be muted or soloed at the same time.
The LED associated with any muted or
soloed channels is used to indicate that
the function is active.
In most cases the mute/solo function will
be configured to act in a pre-bass management signal flow, creating an “input”
mute/solo function. In this case soloing
one channel when bass management is
enabled will result in audio content being
reproduced in both the soloed channel as
well as the subwoofer post-fader monitor output channels. Should the function
be configured for post-bass management
mode soloing a channel will result in only
that specific monitor output channel reproducing the audio content.
Selecting the Solo Mode
As previously discussed in this user guide,
solo operation can be selected between
normal and channel pop. When the normal solo mode has been enabled the solo
LED will light steadily. When the channel
pop solo mode is enabled the solo LED
will flash. It’s easy to change from normal
to pop solo, and vice-versa. Simply press
and hold the mode button and use the surround to stereo button to select the desired
solo mode. The LED associated with the
surround to stereo button displays the active mode. Refer to Figure 10 for details.
The selected mode will be stored in nonvolatile memory so a power down/power
up cycle will not change the selection.
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During normal operation, press and hold the Mute/Solo button
to view and change the solo mode and input delay settings.
for Surround
This LED displays the current setting
of the solo mode. LED not lit means
normal; LED lit means channel pop.
Press the button to change the mode.
This LED displays the current
setting of the input delay.
LED not lit means input delay A
is selected; LED lit means input
delay B is selected. Press the
button to change the setting.
The display shows the currently
selected input delay in milliseconds.
Figure 10. Solo mode and input delay settings
Input Delay
Two input delay settings, A and B, can be
selected and saved during system configuration. These are provided for aligning
the audio input signals with latencies associated with video processing and display
systems. During normal operation of the
StudioComm system the active input delay,
A or B, can be selected. The channel mute/
solo button, stereo to mono button, and 4digit display are used to display and select
the input delay. When the mute/solo button
is pressed and held the LED associated
with the stereo to mono button indicates
whether input delay A or input delay B is active. The 4-digit display will show the active
delay time in milliseconds. While pressing
and holding the mute/solo button the stereo
to mono button can be pressed to change
the selected input delay. Refer to Figure 10
for details. The selected input delay will be
stored in non-volatile memory so a power
down/power up cycle will not change the
selection.
Display and Display Mode
The Model 77’s 4-digit LED display shows
the post-fader surround and stereo digital
and analog monitor output levels as either
the amount of attenuation or the sound
pressure level (SPL). Both will indicate
level in dB. What the digits actually represent will depend upon how the Model 77
has been configured.
Display in dB of Attenuation
If configured for the attenuation mode
the display will show the post-fader monitor output level as an attenuation value in
reference to the maximum output. This is
in the form of 0.5-dB steps less than the
maximum of 0.0 dB. So a display of –40.5
would indicate that the surround or stereo
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monitor output is set to be 40.5 dB below
the maximum level. As the rotary level control is moved counterclockwise the output
level will go down and the indicated value
will get more negative.
Display in dB SPL
If the Model 77 is configured to display the
post-fader digital and analog 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
surround or stereo loudspeaker system
is presenting to users. (Typically, the level
value would actually be in dBC, the Cweighted sound pressure level.) When the
reference level button is enabled, or the
rotary level control is set so that the reference level has been reached, the display
will typically show something in the range
of 82 to 87 dB. Assuming that the monitoring environment has been correctly calibrated, this would indicate that an average
listening level of 85 dB, for example, had
been achieved.
Channel Pop Solo Display
As has been previously discussed, the
channel pop solo mode offers a unique way
of sonically highlighting an individual channel. A channel selected for soloing in this
mode will have its level increased while the
other non-soloed channels will be reduced
in level. To highlight this condition the letters POP will appear in the 4-digit display
whenever a channel is actively being soloed
in the channel pop solo mode. This ensures
that a user will understand that the postfader monitor outputs no longer represent
the true inter-channel level relationships.
Remote Control Inputs
As previously discussed in the Installation
section of this user guide, two remote
control signals can be connected to the
Model 76DA and then configured for
operation. The functions are remote mute
all and remote dim. When an external signal
activates remote mute all the LED on the
Model 77 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 77 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.
Model 71 Control Console
The Model 71 Control Console provides a
rotary level control and a limited number of
pushbutton switches and LEDs for control
and status display. The rotary level control
allows adjustment of the post-fader surround
and stereo monitor output levels. Two buttons, along with associated LEDs, provide
access to the dim and reference level functions. 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 77 and Model 71
units. And, as expected, changes made using a Model 77 will be reflected in the Model
71’s LEDs.
In some applications it may be desirable to
disable operation of a Model 71’s dim and
reference buttons. An example could be
Model 76DA/77 User Guide Issue 9, May 2014
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where non-technical personnel are allowed
only to use the rotary level control. A configuration parameter, previously described
in the Model 71 Control Console Configuration section, allows button operation to
be disabled.
Rotary Level Control
The rotary level control is used to manually
adjust the post-fader surround and stereo
monitor output levels. Its operating characteristics are identical to those of the Model
77 Control Console, discussed earlier in
this section.
Dim
The dim function allows the post-fader surround and stereo monitor output levels to
be reduced by a fixed amount. Its operating characteristics are identical to those of
the Model 77 Control Console, discussed
earlier in this section.
An indication is provided should the dim
button be pressed when button operation
has been disabled. Its associated LED will
flash briefly but no operating change will
occur. The LED will continue to display the
status of the dim function as selected by
other Model 77 and Model 71 units.
Reference Level
The reference level button sets the postfader surround and stereo monitor output
levels to their preset values. The operating characteristics are identical to those of
the Model 77 Control Console, discussed
earlier in this section.
An indication is provided should the reference button be pressed when button
operation has been disabled. The associated LED will flash briefly but no operating
change will occur. The LED will continue
to display the status of the reference level
function as selected by other Model 77 and
Model 71 units.
Technical Notes
Loss of Sync
The Model 76DA relies on an external
timing reference (sync) source for proper
operation. This can be in the form of an
AES3, 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 76DA’s back panel.
Alternately, a configuration choice allows
the L/R input of the AES3 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 76DA 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 are provided. On
the Model 76DA the sync status LED will
flash. On all connected Model 77 Control Consoles the 4-digit LED display will
cease normal operation, instead alternating between the words no and sync. When
a valid sync signal is again connected
the Model 76DA’s sync status LED will
light steadily. On the Model 77 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 76DA’s
configuration.
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If during normal operation the sync source
changes from one valid rate to another a
visual indication is provided. On the Model
77 units the new sample rate—32.0, 44.1,
48.0, 88.2, 96.0, 176.4, or 192.0—will
momentarily be displayed.
Any time that a valid sync signal is not
connected to the Model 76DA 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 76DA the
monitor outputs will automatically switch to
their correct sample rate and audio signals
will again be present.
Power Down
Great care was taken in the Model 76DA’s
design to minimize the chance that clicks,
pops, or other objectionable audio signals
will be present on the post-fader digital
and analog monitor outputs. A power-down
circuit supplies the main microcontroller
integrated circuit with an indication that a
power loss is imminent. When this condition is detected the digital monitor outputs
will switch to silence (digital audio “black”)
in preparation for a complete loss of signal.
Electromechanical relays associated with
the analog monitor outputs will change to
their mute state to minimize the chance of
signal transients reaching the connected
loudspeaker inputs.
Power-Up Messages
Upon mains power being applied to the
Model 76DA all connected Model 77 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 77 and
connected Model 76DA software versions:
1. Displays 77
2. Displays Model 77’s software version
3. Displays Model 77’s unit address
(A1, A2, A3, or A4)
4. Displays 76DA
5. Displays Model 76DA’s main software
version
6. Displays FPgA
7. Displays Model 76DA’s logic device
(FPGA) software version
After a successful system power-up
sequence normal operation will then
commence.
Error Codes Err1 and Err2
Should a problem be encountered during
power up one of two error codes may show
on the Model 77’s 4-digit display. If Err1
displays it indicates that communication is
not taking place with the Model 76DA. The
most likely cause would be incorrect wiring
of the data pair linking the two units. Err2
indicates that the Model 76DA is having
problems with its internal logic device. (A
high-speed field-programmable gate array
(FPGA) serves as the digital “heart” of the
Model 76DA 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 76DA must be returned
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to the factory for service. Note that for the
vast majority of StudioComm systems neither of these error codes, especially Err2,
will ever appear.
Error Code Err3
As previously discussed in this guide, the
bass management function only supports
input signals whose sample rate is 44.1,
48, 88.2, or 96 kHz. If during normal operation this condition is not met, it’s possible
that Err3 will display and the mute all function will be automatically enabled. This will
occur if the bass management function is
configured to be enabled for either or both
the surround and stereo post-fader monitor
outputs and an input with a non-compatible sample rate has been selected. In this
scenario, selecting a different input with a
sample rate of 44.1, 48, 88.2, or 96 kHz
will return the system to normal operation.
Sample Rate Conversion
(SRC)
Circuitry associated with stereo input C
can provide sample rate conversion (SRC)
capability. A digital audio signal connected to that input can have its sample
rate and timing re-synchronized to match
the Model 76DA’s internal timing. While
it would be nice to proclaim that the engineers at Studio Technologies came up
with a unique and exotic circuit to perform
this function it’s really not the case. Several semiconductor companies provide
“single-chip” SRC solutions and an excellent one from AKM was selected for the
Model 76DA. The technical capabilities of
the Model 76DA’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
76DA’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 76DA’s output sample rate is determined by the selected timing reference
(sync) signal and, if required, a configured
value. If a word clock, DARS (AES11), or
AES3 signal is the designated sync source
its rate will be the Model 76DA’s output
sample rate. If a video sync signal is connected, the Model 76DA’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 76DA’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 76DA’s
SRC function to re-synchronize a signal
that proves most valuable. For example,
in typical post-production and broadcast
applications all signals will have a sample
rate of 48 kHz. A Model 76DA and all of its
normally connected input signals will be
“locked” to the main timing reference signal
that supports the 48 kHz sampling rate.
But, as an example, a signal associated
with a portable device, while at a 48 kHz
sampling rate, may not be synchronized
(“genlocked”) to the “house” reference.
Connecting this signal to stereo input C will
cause the SRC function to “lock” it to the
Model 76DA’s rate, thus allowing it to be
monitored over a loudspeaker system. In
addition, the stereo input C direct monitor
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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.
Model 76DA to Control
Console Connections
Figure 7 gives a detailed description of the
signals that connect the Model 76DA Central Controller to the one or more Model 77
or Model 71 Control Consoles. The Model
76DA provides 12 volts DC 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 76DA’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 76DA communicates with each
Model 77 and Model 71 unit 20 times per
second, receiving button and rotary level
control information and sending LED and
4-digit display status data.
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 digital audio monitor output channel
data are actively controlled by the Model
76DA’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 76DA’s hardware is capable of
routing the C/U/V bit information from any
of the L/R inputs, as well as the sync input,
to the main logic device (FPGA) and then
on to the digital audio transmitter (DIT) integrated circuits. This is provided for future
use and is not active at this time.
“Hot” Disconnection of
Control Consoles
There’s no problem relocating one or
more Model 77 or Model 71 Control
Consoles while the StudioComm system
is operating. You can disconnect the 9-pin
interconnecting cable, move the unit (or
units), and then reconnect without issue.
Upon disconnection of all control consoles
the Model 76DA Central Controller will
mute the internal digital audio channels
as well as saving the current operating
parameters. No clicks, pops, or other
noises will occur when the Model 77 or
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Specifications
Model 76DA Central Controller
General Audio:
Supported Sample Rates: 32, 44.1, 48, 88.2, 96,
176.4, and 192 kHz
Word Length: 24 bits maximum
Internal Processing: 32 bits
Input-to-Output Latency: two samples (e.g., 0.042
milliseconds @ 48 kHz sample rate)
Digital Audio Inputs: 5 (18 audio channels)
Configuration: two surround (5.1) and three stereo
Type: unbalanced AES3/SMPTE 276M (75 ohms/
1 Vpp)
Connectors: BNC (per IEC 60169-8 Amendment 2)
Sample Rate Conversion (SRC):
Application: available on Stereo Input C
Input Sample Rate Range: 8 to 216 kHz, limited to
1/6 to 6 times the output sample rate
Latency: 1 millisecond, nominal
Sync Source: configured to follow L/R of currently
selected input or signal connected to sync input
Sync Input:
Compatible Sources: word clock, DARS (AES11),
bi-level video, tri-level video
Jitter: 4 ns pp maximum
Connector: BNC (per IEC 60169-8 Amendment 2)
Termination: 75 ohms, selectable on/off
Digital Monitor Outputs: 16 (eight pairs)
Configuration: organized as two surround (5.1)
and two stereo
Dynamic Range:
Type: balanced AES3 (110 ohms/5 Vpp) or unbal
anced AES3/SMPTE 276M (75 ohms/1 Vpp),
selectable
Connector: 25-pin female D-subminiature (DB-25F)
Analog Monitor Outputs: 8
Configuration: organized as one surround (5.1)
48 kHz sample rate (scales up or down depending
on actual sample rate)
Post-Fader Monitor Output Level Offsets:
each surround and stereo channel independently
adjustable in 0.5-dB steps over a ±12-dB range.
(Digital and analog outputs associated with a
specific channel share the same setting.)
Bass Management:
Supported Sample Rates: 44.1, 48, 88.2, and
96 kHz only
Crossover Frequency and Type: –6 dB @ 40, 50,
60, or 80 Hz, symmetrical for low-pass and highpass filters, maximally flat
Filter Slope: 12 or 24 dB/octave
Overall Operation: independent on/off selectable
for surround and stereo post-fader monitor outputs
Downmix:
Functions: surround to stereo, stereo to mono
Surround to Stereo:
L @ 0 or –3 dB;
R @ 0 or –3 dB;
C @ –3 or –6 dB summed with L and R;
LFE @ full attenuation or –6 dB summed with
L and R;
LS @ –3 or –6 dB summed with L;
RS @ –3 or –6 dB summed with R;
C, SUB, LS, and RS monitor outputs mute
Stereo to Mono:
L @ –3 dB summed with R @ –3 dB to C;
L, R, LS, RS, and SUB monitor outputs mute
For a surround input this results in the C output being the sum of L @ –3 or –6 dB, R @ –3 or –6 dB;
C @ –3 or –6 dB, LFE @ full attenuation or –6 dB;
LS @ –6 or –9 dB, and RS @ –6 or –9 dB.
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Control Console Interface:
Type: RS-485, 115.2 kbit/s, 8-1-N
Polling Interval: 50 milliseconds
Power: 12 volts DC, 500 milliamperes maximum
Connector: 9-pin female D-subminiature (DE-9F)
Remote Control Inputs: 2
Functions: remote mute all, remote dim
Type: 5 Vdc logic, activates on closure to system
common
Connector: 9-pin female D-subminiature (DE-9F)
AC Mains:
Requirement: 100 to 230 V, +10/–15%, 50/60 Hz,
15 W maximum
Connector: 3-blade, IEC 320 C14-compatible
(mates with IEC 320 C13)
Dimensions:
19.00 inches wide (48.3 cm)
1.72 inches high (4.4 cm)
7.00 inches deep (17.8 cm)
Mounting: one space (1U) in a standard 19-inch
rack
Weight: 3.6 pounds (1.6 kg)
Model 71 Control Console
Application: up to three Model 71 Control
Consoles can be connected to a Model 76DA
Central Controller
Power: 12 volts DC nominal (9 volts DC minimum),
maximum current 35 milliamperes, provided by
Model 76DA Central Controller
Control Data:
Type: RS-485
Data Rate/Format: 115.2 kbit/s, 8-N-1
Connector: 9-pin female D-subminiature (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.
Model 77 Control Console
Application: up to four Model 77 Control Consoles
can be connected to a Model 76DA Central
Controller
Power: 12 volts DC nominal (9 volts DC minimum),
maximum current 100 milliamperes, provided by
Model 76DA Central Controller
Control Data:
Type: RS-485
Data Rate/Format: 115.2 kbit/s, 8-N-1
Connector: 9-pin female D-subminiature (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)
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Appendix A—Connection Pin-Out
Charts
TASCAM® Signal Signal
Connections Channel High (+) Low (–) Shield
Pre-Fader L/R 1 24 12 25
Pre-Fader C/SUB 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/SUB 6 4 17 5
Post-Fader LS/RS 7 15 3 16
Post-Fader Stereo 8 1 14 2
Notes: 1) All signals transformer-coupled digital audio;
selectable for balanced or unbalanced AES3
compatibility.
2) Connector type on Model 76DA 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 Digital Monitor Outputs
Signal Signal
Connections High (+) Low (–) Shield
Surround L 24 12 25
Surround R 10 23 11
Surround C 21 9 22
Surround SUB 7 20 8
Surround LS 18 6 19
Surround RS 4 17 5
Stereo L 15 3 16
Stereo R 1 14 2
Notes: 1) Connector type on Model 76DA is 25-pin
D-subminiature female (DB-25F). Installer must provide
male (DB-25M). Connector uses 4-40 threaded inserts
for locking with mating plug.
2) Wiring scheme follows TASCAM DA-88 convention.
Standard DA-88-type wiring harnesses are directly
compatible, with the exception of 4-40 screw threads
being required.
Connections for Analog Monitor Outputs
Signal Pin Direction
Data + (RS-485/RS-422) 7 Not used
Data – (RS-485/RS-422) 2 Not used
Data Shield 1 Shield
Remote Mute All 5 Input
Remote Dim 6 Input
Remote Spare 1 8 Input
Remote Spare 2 9 Input
Remote Input Common 4 Common
Note: Connector type on Model 76D
D-subminiature female (DE-9F). Connector uses
4-40 threaded inserts for locking with mating plug.
A is 9-pin
Signal Pin Direction
Data + (RS-485) 1 To/From Models 77/71
Data – (RS-485) 6 To/From Models 77/71
Data Shield 2 To/From Models 77/71
DC + (12 V) 4 To Models 77/71
DC – (12 V Return) 9 To Models 77/71
DC Power Shield 5 To/From Models 77/71
Note: Connector type on Model 76DA is 9-pin
D-subminiature female (DE-9F). Connector uses
4-40 threaded inserts for locking with mating plug.
Connections between Model 76DA and
Model 77 and Model 71
Connections for Remote Control Inputs
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Appendix B—Sync Input Sources
The Model 76DA’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 AES3: 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 FormatVideo Format, continued
NTSC (“Black Burst”)1035i/59.98 Hz
PAL (“Black Burst”)1035i/60 Hz
525i/59.94 Hz1080i/50 Hz
525p/59.94 Hz1080i/59.94 Hz
625i/50 Hz1080i/60 Hz
625p/50 Hz1080p/23.98 Hz
720p/23.98 Hz1080p/24 Hz
720p/24 Hz1080p/25 Hz
720p/25 Hz1080p/29.97 Hz
720p/29.97 Hz1080p/30 Hz
720p/30 Hz1080psf/24 Hz
720p/50 Hz1080psf/23.98 Hz
720p/59.94 Hz
720p/60 Hz
Model 76DA/77 User Guide Issue 9, May 2014
Studio Technologies, Inc. Page 53
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