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

for Surround Model 76DA Central Controller and Model 77 Control Console User Guide
for Surround
Model 76DA Central Controller and
Model 77 Control Console
User Guide
Issue 1, September 2010
This User Guide is applicable for systems consisting of:
Model 76DA: serial number M76DA-00151 and later with software version 3.00 and higher;
Model 77: serial number M77-00265 and later with software version 2.01 and higher
© 2010 by Studio Technologies, Inc., all rights reserved
www.studio-tech.com
50241-0910, Issue 1
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for Surround
Table of Contents
Introduction ................................................................... 5
Installation .................................................................... 8
Configuration ................................................................16
Operation ......................................................................33
Technical Notes ............................................................39
Specifications ...............................................................43
Appendix A—Connection Pin-Out Charts ....................45
Appendix B—Sync Input Sources ................................46
Model 76DA/77 User Guide
Studio Technologies, Inc.
Issue 1, September 2010
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Model 76DA/77 User Guide
Studio Technologies, Inc.
for Surround
Introduction
What This User Guide Covers
This User Guide is designed to assist you
when installing and using the Model 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, postproduction, and broadcast facilities. And
with audio-with-picture applications becoming so prevalent, additional monitoring
challenges have arisen. Studio Technologies has addressed these needs with the
StudioComm for Surround Model 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, downmix and
mute/solo functions, 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
Model 76DA/77 User Guide
Studio Technologies, Inc.
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 digital audio input, digital
and analog monitor output, processing,
and support circuitry. The Model 76DA
provides two surround (5.1) and three
stereo digital audio inputs. These unbalanced digital inputs are AES3id/SMPTE
276M-compliant; sources of this type are
ubiquitous in most post-production and
broadcast environments. The inputs allow
a sample rate of up to 192 kHz and a bit
depth of up to 24 to be directly supported.
Circuitry associated with one of the stereo
inputs provides sample rate conversion
(SRC) capability, allowing a wide range of
digital audio sources to be monitored. Up
to 340 milliseconds of input delay can be
selected to compensate for processing
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delays in an associated video path. 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), bi-level video,
or tri-level video can be connected. Alternately, the L/R connection of the actively
selected surround or stereo input source
can serve as the timing reference.
For installation flexibility the digital monitor
outputs can be configured for compatibility
with equipment that requires AES3 (“balanced”) or AES3id (“unbalanced”) digital
audio signals. When selected for AES3
compatibility the output impedance is 110
ohms with a signal level of 5 volts peak-topeak (Vpp). For AES3id operation the impedance is 75 ohms and the level is 1 Vpp.
Great care was taken in designing the
system’s architecture, ensuring that the
character of the audio input signals is preserved. All audio processing is performed
in 32 bits using a high-speed field-programmable gate array (FPGA) integrated circuit.
A range of digital and analog surround
(5.1) and stereo 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.
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
D-subminiature connectors. One 9-pin
Figure 1. Model 76DA Central Controller Front Panel
Control console
status LED
Sync status
LED
Figure 2. Model 76DA Central Controller Back Panel
AC mains input
To/from
Models 77 &
71 Control
Consoles
Remote control
inputs
Issue 1, September 2010
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Digital
monitor
outputs
Analog
monitor outputs
Surround Input B
Sync
Input
Stereo
Input C
Stereo Input A and
Stereo Input B
Surround Input A
Model 76DA/77 User Guide
Studio Technologies, Inc.
for Surround
Channel mute/solo
Mute/solo
mode
Downmix
Input source
select
Monitor output
level display
Post-fader surround
monitor output
• Surround/stereo
• Reference level
• Mute all
• Dim
• Rotary level control
Figure 3. Model 77 Control Console Front Panel
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 “D-sub” 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.
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”).
0.5-dB steps. The auto mute all function
causes the post-fader surround and stereo
digital and analog monitor output channels
to automatically mute whenever the output
level control reaches maximum attenuation. Using the reference level function, the
post-fader surround and stereo digital and
analog monitor output levels can be set to
a pre-configured value. This is provided for
audio-with-picture applications that require
a specific monitor output level. The reference level is easily configured by taking an
electronic “snapshot” of the desired monitor output level. For operator confirmation a
4-digit LED readout can display the level of
the post-fader surround and stereo digital and analog monitor output channels.
To match the needs of a facility, it can be
configured to display either the attenuation
level or the sound pressure level (SPL).
The 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
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
Additional Details
Model 76DA/77 User Guide
Studio Technologies, Inc.
Issue 1, September 2010
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for Surround
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 monitor output channel to be
raised while the level of the other channels
is reduced. This helps to emphasize the
content on one channel without fully muting the others. Broadcast applications can
benefit from the channel pop solo mode
by allowing, for example, the center channel to be highlighted while still maintaining some level on the other channels. The
amount of level increase—the “pop”—as
well as the amount of attenuation can be
configured to meet the needs of specific
applications or users.
Two functions allow the input sources to be
checked for level or phase inconsistencies.
The 5.1 to stereo downmix function is used
to create a stereo signal from the selected
surround (5.1) source. The stereo to mono
downmix function allows audio on the left
and right channels to be added (summed)
and monitored on the center output channel. The two downmix functions can be
simultaneously enabled, allowing a surround source to be checked for mono compatibility. The downmix functions always
impact the post-fader surround and stereo
digital and analog monitor outputs. A configuration setting allows the pre-fader surround digital monitor output to be selected
for pre- or post-downmix operation.
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For flexibility, the StudioComm for Surround
system is designed to easily integrate with
equipment such as production intercom
systems, on-air or recording tally signals,
and audio consoles. Two remote-control
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 postfader surround and stereo digital and
analog 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 and digital 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.
Model 76DA/77 User Guide
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Mounting the Model 76DA
The Model 76DA Central Controller
requires one space (1U) in a standard
19-inch (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 D-subminiature connectors. 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.
Digital Audio Inputs
Two surround (5.1) and three stereo digital
audio sources can be connected. All sources can be monitored using the pre- and
post-fader surround and post-fader stereo
digital and analog 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 function.) Stereo input C is also routed
to the stereo input C direct digital monitor
output.
The digital audio inputs support digital
audio signals with a sampling rate of up to
192 kHz and a word length (depth) of up
Model 76DA/77 User Guide
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to 24 bits. It’s best if the connected signal
sources maintain a common sample rate
and timing reference. Having all signals
“locked” together helps to ensure proper
handling by the Model 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 AES3id standard. In
broadcast or post-production environments
these signals may also be referred to as
following the SMPTE 276M standard. This
signal type has a nominal impedance of
75 ohms with a nominal signal level of
1 Vpp. As expected, these digital audio
sources should be provided in the form of
coaxial cables with BNC plugs attached.
Balanced AES3 digital audio signals can
also be used with the Model 76DA’s inputs
if external coupling transformers (“baluns”)
are utilized. These impedance-matching
(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.
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Digital Monitor Outputs
The 25-pin 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 prefader surround digital monitor output
channels are intended for connection to
metering or monitoring equipment that
requires uninterrupted full-level signals.
The post-fader surround digital monitor
output channels are intended to connect to
a 5.1 loudspeaker system. The 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 AES3 or AES3id digital
audio sources. The digital monitor outputs
are configured in two groups with separate
choices available for the pre-fader surround/
stereo input C direct group and post-fader
surround/post-fader stereo group. When
a group is set for AES3 (110 ohms/5 Vpp)
the signals are compatible with AES3 interfaces. Signals of this type are normally
interconnected using shielded twisted-pair
cable terminated with 3-pin XLR connectors. When a group is configured for AES3id
(75 ohms/1 Vpp) the source impedance and
signal level are compatible with the requirements of AES3id interfacing. These signals
Issue 1, September 2010
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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 D-sub plug
(male) on one end and the desired connectors on the other end will be used for
connecting to the digital monitor outputs.
The D-subminiature connector follows the
TASCAM® wiring convention, organizing
the 25 pins into eight groups of three pins
each; one pin remains unused. Each set of
three pins provides an independent interface. In the analog world this would allow
eight audio signals to be transported. But
with AES3/AES3id digital audio signals
this allows support for 16 audio channels;
eight interfaces each supplying two audio
channels.
A wiring assembly prepared for the Model
76DA’s digital monitor outputs, when
configured for AES3 (110 ohms/5 Vpp),
would be identical to that of a DA-88-style
output assembly. An assembly of this type
would have a male 25-pin D-subminiature
connector (DB-25M) on one end and eight
3-pin male XLR connectors on the other.
A wiring assembly prepared for the Model
76DA’s digital monitor outputs, when set
for AES3id (75 ohms/1 Vpp), would typically have eight BNC plugs attached.
For compatibility with AES3 balanced
digital audio signals connect the D-sub’s
+ terminal as signal high and the – terminal as signal low. In most applications a
3-pin XLR plug (male) will be used. In this
case the + terminal would go to pin 2 of
the XLR, the – terminal to XLR pin 3, and
the shield terminal to XLR pin 1.
Model 76DA/77 User Guide
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for Surround
For compatibility with AES3id unbalanced
digital audio signals connect the D-sub’s
+ terminal as signal high, and both the
– and shield terminals as the signal low/
shield. When terminating to a BNC plug the
D-sub’s + terminal should connect to the
center pin; the – and the shield connections should go to the “body” of the BNC
plug. To clarify, for optimal operation it is
best to connect both the – and shield 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.
Connections
TASCAM® Signal
Channel High (+)
Pre-Fader L/R
Signal
Low (–)
Shield
1
24
12
25
Pre-Fader C/LFE
2
10
23
11
Pre-Fader LS/RS
3
21
9
22
Stereo Input C Direct
4
7
20
8
Post-Fader L/R
5
18
6
19
Post-Fader C/LFE
6
4
17
5
Post-Fader LS/RS
7
15
3
16
Post-Fader Stereo
8
1
14
2
Notes: 1) All signals transformer-coupled digital audio;
selectable for AES3 or AES3id 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.
Figure 4. Connections for Digital Monitor Outputs
Model 76DA/77 User Guide
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Pre-Fader Surround Digital Monitor
Output
The pre-fader surround digital monitor
output channels are intended to connect
to metering, measurement, or other signal
monitoring equipment that requires uninterrupted, full-level digital audio signal
sources.
Stereo Input C Direct Digital Monitor
Output
The stereo input C direct digital monitor
output is intended for use in site-specific
applications. It provides an uninterrupted,
full-level digital audio signal source that
is post-SRC and input delay in the signal
chain.
Post-Fader Surround Digital Monitor
Output
The post-fader surround digital monitor
output channels are designed for connection to digital inputs on audio amplifiers
associated with monitor loudspeakers.
Alternately, they could be connected to the
inputs of loudspeakers that contain integrated amplifiers with digital audio input
capability.
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
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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 XLR plugs (male) will be used
to interface with the inputs on the associated amplifiers or amplified speakers. In this
case the + terminal would go to pin 2 of the
XLR, the – terminal to XLR pin 3, and the
shield terminal to XLR pin 1.
Balanced operation of the analog monitor
outputs is the preferred connection method
but unbalanced operation does not pose a
problem. To connect to an unbalanced load
connect the + terminal as signal high, and
only the Model 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
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.
Issue 1, September 2010
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Connections
Signal
High (+)
Signal
Low (–)
Shield
Surround L
24
12
25
Surround R
10
23
11
Surround C
21
9
22
Surround LFE
7
20
8
Surround LS
18
6
19
Surround RS
4
17
5
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.
Figure 5. Connections for Analog Monitor
Outputs
Sync Input
The Model 76DA requires a timing reference (sync) signal so that the digital audio
input and 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
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
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for Surround
the sample rate of the associated digital
audio sources. DARS (digital audio reference source) is a timing signal compliant
with the AES11 standard. It’s sometimes
referred to as “AES3-black.” Technically it
is similar to an AES3 or AES3id signal but
is generated specifically as a timing reference signal. Bi-level video sync signals
were originally provided to support NTSC
and PAL broadcast applications, although
they continue to be used by contemporary equipment. Tri-level sync signals
were primarily associated with facilities
that supported high-definition (HD) video
equipment, however the importance of this
type of sync seems to be waning. Both
bi-level and tri-level signals can be found
at numerous rate combinations, configured
to allow for compatibility with the various
video formats.
With the wide range of allowable sync
sources proper Model 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
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.
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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 overcurrent 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 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
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 76DA is 9-pin D-subminiature
female (DE-9F). Connector uses 4-40 threaded inserts
for locking with mating plug.
Figure 6. Connections for Remote Control
Inputs
Issue 1, September 2010
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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.
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
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.
Figure 7. Connections between Model 76DA and
Model 77 and Model 71
Issue 1, September 2010
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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 pinout scheme was designed to allow creation
of an interconnecting cable which uses
commonly available 2-pair audio cable.
This cable, consisting of two twisted pairs
each with an individual shield, is typically
sleek, flexible, and available in many colors. One pair and shield can be used for
the data connections while the other pair
and shield can be used for the DC connections. This implementation has the advantages of providing a shield for the data
path and a more robust common connection (two conductors including the shield)
for the DC power circuit.
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 volt 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
DC-carrying 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
Model 76DA/77 User Guide
Studio Technologies, Inc.
for Surround
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 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 volt DC power signals between
all the units will be multed. A custom cable
implementation requires just four pins to be
connected: pin 1 (data +), pin 6 (data –),
pin 4 (DC +), and pin 9 (DC –).
To make installation simple, a “bus” cable
assembly can be created using a short
length of ribbon cable with one male
and multiple female 9-pin D-subminiature
insulation-displacement connectors
attached. Then standard 9-pin cables can
link the control consoles with the connectors on the bus cable.
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 V, 50/60 Hz.
Being a “universal input” device, there are
no switches to set or jumpers to install to
match a location’s mains voltage. The unit
uses a 3-pin IEC 320 C14-type inlet connector to mate with a detachable mains
cord. All units are supplied with a mains
cord that has a North-American standard
plug (NEMA 5-15L) on one end and an
IEC 320 C13 socket on the other. Units
bound for other destinations require that
the appropriate cord be used. The wire
colors in the mains cord must conform to
the internationally recognized color code
and should be terminated accordingly:
Connection
Neutral (N)
Line (L)
Protective Earth (E)
Wire Color
Light Blue
Brown
Green/Yellow
Safety Warning: The Model 76DA
does not contain an AC mains disconnect switch; the AC mains cord
plug serves as the disconnection
device. Safety considerations require
that the plug and associated outlet
be easily accessible to allow rapid
disconnection of AC mains power
should it prove necessary.
Refer to the previous paragraphs of this
user guide where the issues involving
Model 76DA to Model 77 cable length are
Model 76DA/77 User Guide
Studio Technologies, Inc.
Issue 1, September 2010
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for Surround
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.
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.
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.
Configuration
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
using the dim and reference level LEDs, as
shown in Figure 8 in the Operation section.
When this is complete the Model 71 will
begin normal operation and its status LED
will light if communication is established
with the Model 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.
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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.
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 using a Model 77 Control Console. However,
one configuration choice is available for
each of the connected Model 71 Control
Consoles.
Configurable Parameters
Many StudioComm functions can be configured to meet the exact needs of an
installation. A Model 77 Control Console
is used to display and select the desired
Model 76DA/77 User Guide
Studio Technologies, Inc.
for Surround
system configuration. Here’s an overview
of what can be configured:
• Model 77 Device Address (unique for
each unit)
• Stereo Input C Sample Rate Converter
• Post-Fader Stereo Digital and Analog
Monitor Outputs
• Sync Source
• Sync Input Termination
• Audio-Synced-to-Video Sample Rate
• Digital Monitor Output Types
• Reference Level
• Overall Display Mode
• Reference Level in dB SPL
• Auto Reference Level Off
• Dim Level
• Remote Inputs
• Input Delay
• LFE Downmix Mode
• Pre-Fader Surround Digital Monitor
Output Mode
• Channel Pop Solo Mode Offset Levels
The configuration diagrams, located later
in this section, give details on setting each
parameter. An overview of each configurable parameter is provided in the following
paragraphs.
Entering and Exiting the
Configuration Mode
A small button is located on the back of
each Model 77 Control Console, adjacent
to its 9-pin 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
Model 76DA/77 User Guide
Studio Technologies, Inc.
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 digital and analog 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 configure button a pain to use, but it’s
supposed to be that way! Seriously, the top
of the button is slightly recessed from the
back panel, making it harder to accidentally activate. We didn’t want normal operation to cease because someone pushed
a Model 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
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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.
However, only the individual device address is stored in each Model 77 and
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 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
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signal with a sample rate over a range of
8 to 216 kHz can be properly monitored
by the system. This capability can be
especially useful with signals that are not
synchronized with respect with the others
connected to the Model 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 monitor output, separate post-fader
stereo digital and analog monitor outputs
are also provided. By default these stereo outputs can be enabled by an operator. In applications where stereo monitor
loudspeakers are not connected to the
post-fader stereo digital or analog 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.
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.
Model 76DA/77 User Guide
Studio Technologies, Inc.
for Surround
Sync Input Termination
The sync input circuitry can be configured
to terminate the signal connected to the
back-panel sync input BNC connector.
When termination is selected a 75 ohm
load is applied to the signal. When the
sync input is not terminated the input impedance is very high, essentially applying
no load to the source. If the sync source
is connected only to the Model 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 appropriate. If the digital
output signals are going to be connected
to unbalanced AES3id inputs then the
Model 76DA/77 User Guide
Studio Technologies, Inc.
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.
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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 configure 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
pressing the reference level button. The
SPL meter should display the desired level.
If not, repeat the calibration procedure to
achieve the desired goal.
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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). Used in conjunction with the reference level in dB SPL
configuration and the stored reference
level, SPL mode allows a user to see a
visual representation of the SPL level that
is present in the listening environment.
While it takes a little more care to correctly
implement the SPL display mode, it can
offer an enhanced experience for StudioComm users.
Reference Level in dB SPL
The reference level in dB SPL configuration allows a specific SPL value to be
associated with the stored reference level
Model 76DA/77 User Guide
Studio Technologies, Inc.
for Surround
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 digital
and analog monitor outputs’ current level.
There are four dim level values available:
–10.0, –15.0, –20.0, and –25.0 dB.
Remote Mute All
Two configuration choices are associated
with the remote mute all function: disabled
and enabled. To utilize the remote mute all
Model 76DA/77 User Guide
Studio Technologies, Inc.
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 selected time delay applies
to all input signals and cannot be applied
selectively. The configured delay time is
referenced to a sample rate of 48 kHz.
In the case of input signals with a sample
rate of 48 kHz the delay range is 0 to
340 milliseconds in 1-millisecond steps.
For other sample rates the time must be
linearly scaled. For example, for a sample
rate of 96 kHz the actual time range is 0 to
170 milliseconds. In this case selecting a
delay of 120 on the Model 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.
LFE Downmix Mode
By default, when the 5.1 to stereo downmix function is active the LFE channel
associated with a surround input is muted.
This removes LFE content from the “downmixed” signal. In most applications this is
appropriate. However, for special situations
a configuration mode allows the LFE channel to be part of the downmix signal flow.
When the LFE downmix mode is enabled,
if surround input A or B is the currently selected input and the 5.1 to stereo downmix
function is active, the LFE signal level is
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for Surround
reduced in level by 6 dB and added to both
the left and right output channels. As expected, even when the LFE downmix mode
is active the LFE output channel will still
mute when 5.1 to stereo downmix is active.
Pre-Fader Surround 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 prefader surround digital monitor output signals. If the post-downmix mode is selected
the pre-fader surround digital monitor outputs will reflect the actions of the downmix
functions. This choice would be correct if,
for example, level meters were connected
to the pre-fader surround digital monitor
outputs. In this scenario an operator would
want to visually observe the actions that the
downmix functions impart on the signals.
Channel Pop Solo Mode Offset
Levels
Two parameters can be configured that
determine how the channel pop solo function impacts audio levels. The up offset level
sets the amount of increase (gain) that a
channel will experience when it is soloed
in the channel pop solo mode. The down
offset level sets the amount of decrease
(attenuation) that the non-soloed channels
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will experience when a channel is active in
the channel pop solo mode.
Restore Factory Defaults
The restore factory defaults function is provided primarily for factory use. In this way
a system can be shipped with the default
settings selected. While you are welcome
to use this function, be careful so that your
configuration efforts aren’t wasted. Specifically, be aware that the reference level is
reset to minimum level. All the other parameters are fairly easy to set up, but resetting
the reference level would require getting
out an SPL meter and a calibrated signal
source. This is a hassle you may not need!
Model 71 Control Console
Configuration
The only configuration choice available on
a Model 71 is its device address. It must be
selected so as not to conflict with the device
address of any other connected Model 71
or Model 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
Figures 8 and 9 for details.
A small button is located on the back of
each Model 71 Control Console, adjacent
to the 9-pin D-sub connector. Pressing and
holding this button for two seconds places
this specific unit in its configuration mode;
normal operation of the Model 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. The dim and
Model 76DA/77 User Guide
Studio Technologies, Inc.
for Surround
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.
To leave the configuration mode and return
a Model 71 to normal operation requires
one last action; again press and hold its
configure button for two seconds. The
selected device address will be stored in a
nonvolatile memory device that is located
inside this specific Model 71.
Figure 8. Model 71 Control Console Front and
Back Panels
Address
Dim LED
Reference Level LED
A1
OFF
OFF
A2
OFF
ON
A3
ON
OFF
A4
ON
ON
Figure 9. Model 71 Device Address Chart
Model 76DA/77 User Guide
Studio Technologies, Inc.
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Configuration—Entering and Exiting Configuration Mode
and hold the configuration
 Press
button for 2 seconds to enter or
exit the configuration mode.
These LEDs will light alternately
when configuration mode is active.
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Model 76DA/77 User Guide
Studio Technologies, Inc.
for Surround
Configuration—Model 77 Device Address, Stereo Input C
Sample Rate Converter, and Post-Fader Stereo Digital and
Analog Monitor Outputs
and hold the Mute/Solo button
 Press
to display and select the Model 77’s
device address, stereo input C sample
rate converter, and post-fader stereo
digital and analog monitor outputs.
This LED displays the configuration of the stereo
input C sample rate converter (SRC). LED not
lit means SRC is bypassed; LED lit means SRC
enabled. Use the button to change the configuration.
When the Mode
button is pressed,
these LEDs
display the status
of the post-fader
stereo digital
and analog
monitor outputs
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.
Use the Level control to change this
specific Model 77’s device address.
Address can be either A1, A2, A3, or A4.
Default:
Device address A1.
Stereo input C sample rate converter enabled.
Post-fader stereo digital and analog monitor outputs 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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Studio Technologies, Inc.
Issue 1, September 2010
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for Surround
Configuration—Sync Source, Sync Input Termination,
Audio-Synced-to-Video Sample Rate, and Digital Monitor
Output Types
This LED displays the configuration
of the sync input termination. LED
not lit means sync input is not terminated; LED lit means terminated with
75 ohms. Use the button to change
the configuration.
Use the Channel Solo C and LFE buttons
to select the pre-fader surround/stereo
input C direct digital monitor output
type. Use the buttons to change the
configuration. C LED lit means AES3id
(75 ohms/1 Vpp); LFE LED lit means
AES3 (110 ohms/5 Vpp).
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
AES3id (75 ohms/1 Vpp); RS LED lit
means AES (110 ohms/5 Vpp).

Press and hold
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 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.
Use the level control to adjust the audiosynced-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 AES3 (110 ohms/5 Vpp).
Post-fader surround/stereo digital monitor output type AES3 (110 ohms/5 Vpp).
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Studio Technologies, Inc.
for Surround
Configuration—Reference Level
and hold the Reference Level button for 5 seconds to take a “snapshot”
 Press
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.
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.
Model 76DA/77 User Guide
Studio Technologies, Inc.
Issue 1, September 2010
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for Surround
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 button to
 display
and set the overall display mode,
the reference level in dB SPL, and auto
reference level off.
Default:
When the Mute All button is pressed,
use the Level control to adjust the
reference level in dB SPL.
Attenuation display mode selected.
85.0 dB SPL reference level.
Auto ref level off disabled.
Issue 1, September 2010
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Model 76DA/77 User Guide
Studio Technologies, Inc.
for Surround
Configuration—Dim Level, Remote Mute All, Remote Dim,
and Input Delay
This LED displays the configuration of
remote mute all. LED not lit means
remote mute all is disabled; LED lit
means enabled. Use the button to
change the configuration.
This LED displays the configuration
of remote dim. LED not lit means
remote dim is disabled; LED lit
means enabled. Use the button to
change the configuration.
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.
and hold the Dim button to
 Press
display and select the dim level,
remote mute all, remote dim, and
input delay.
Default:
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.
–20 dB dim level.
Remote mute all enabled.
Remote dim enabled.
Input delay 0 ms.
Model 76DA/77 User Guide
Studio Technologies, Inc.
Issue 1, September 2010
Page 29
for Surround
Configuration—LFE Downmix Mode 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 outputs are pre-downmix; LED R lit means
outputs are post-downmix. Use the buttons to change
the configuration.
This LED displays the configuration of the LFE
downmix mode. LED not lit means LFE downmix mode is disabled; LED lit means enabled.
Use the button to change the configuration.

Press and hold
the Surround to
Stereo button to
display and set
the LFE downmix
and pre-fader
surround digital
monitor output
modes.
Default:
LFE downmix disabled.
Pre-fader surround digital monitor outputs pre-downmix.
Issue 1, September 2010
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Model 76DA/77 User Guide
Studio Technologies, Inc.
for Surround
Configuration—Channel Pop Solo Mode Offset Levels

Press and hold
the Surround A
button to display
and select the
channel pop solo
up offset level.

Press and hold
the Surround B
button to display
and select the
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.
The range is –0.0 to –12.0 in 0.5 dB steps and full mute.
Full mute is selected by adjusting the level control past
–12.0, at which point the display will show – – – –.
Default:
6.0 dB channel pop solo up offset level.
–6.0 dB channel pop solo down offset level.
Model 76DA/77 User Guide
Studio Technologies, Inc.
Issue 1, September 2010
Page 31
for Surround
Configuration—Restore Factory Defaults
and hold both the Surround/Stereo and Dim buttons for 5 seconds
 Press
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.
Factory Defaults:
Device address A1.
Stereo input C sample rate converter enabled.
Post-fader stereo digital and analog monitor outputs can
be enabled.
Sync source is L/R of currently selected input.
Sync input terminated.
Audio-synced-to-video sample rate 48 kHz.
Pre-fader surround/stereo input C direct digital monitor
output type AES3 (110 ohms/5 Vpp).
Post-fader surround/stereo digital monitor output type
AES3 (110 ohms/5 Vpp).
Reference level set for –60.0 dB post-fader monitor
output level.
Attenuation display mode selected.
85.0 dB SPL reference level.
Auto reference level off disabled.
–20 dB dim level.
Remote mute all enabled.
Remote dim enabled.
Input delay 0 ms.
LFE downmix disabled.
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.
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.
Issue 1, September 2010
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Model 76DA/77 User Guide
Studio Technologies, Inc.
for Surround
Operation
Now that you’ve installed and configured
the system, you’re ready to go. You should
find operation very easy. However, taking
time to study this section of the guide may
prove valuable.
Upon power up the system will return to
the last operating condition, including the
selected source, downmix modes, etc. As
a precaution, however, the post-fader surround 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
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
Model 76DA/77 User Guide
Studio Technologies, Inc.
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.
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.
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
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for Surround
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. Please refer to the Specifications section of this guide if you’d like
a detailed description of how the downmix
functions perform their tasks.
A specific downmix function can only be
enabled when it is applicable for the currently selected input source. This means
that the 5.1 to stereo downmix function can
only be enabled when surround input A or
B is selected.
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
5.1 to stereo downmix function is enabled,
this condition will be “remembered” when
switching to one of the stereo input sources. Upon returning to surround input A, the
5.1 to stereo downmix function will again
become active.
5.1 to Stereo
When the 5.1 to stereo downmix function
is enabled the LS, RS, and C channels
associated with a surround source are
combined (“folded down”) with the L and
R signals to create a 2-channel stereo
(left and right) signal. And, depending on
the system’s configuration, the LFE channel may also be combined with the L and
R signals. The resulting stereo signal,
Issue 1, September 2010
Page 34
sometimes known as LoRo, is routed to
the L and R surround digital and analog
monitor output channels. The C, LFE, LS,
and RS digital and analog monitor output channels are muted. By utilizing this
downmix function phase relationships and
inter-channel level issues can be quickly
observed.
Stereo to Mono
The stereo to mono downmix function
combines the L and R audio channels to
create a single-channel monaural signal.
This signal is sent out the C surround
digital and analog monitor output channels
while the L, R, LS, RS, and LFE digital and
analog monitor output channels are muted.
When a surround source has been
selected for monitoring, the 5.1 to stereo
downmix function will automatically enable
whenever the stereo to mono downmix
function is enabled. This ensures that an
operator will hear a mono signal created
by folding down all channels associated
with the selected surround input.
Monitor Output General
Functions
Four buttons and one rotary control are
associated with the post-fader surround
and stereo digital and analog monitor output functions. The buttons control operation of the surround and stereo digital and
analog 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.
Model 76DA/77 User Guide
Studio Technologies, Inc.
for Surround
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 digital
and analog monitor output channels are
active. The channels associated with the
post-fader stereo digital and analog monitor outputs are muted. When the stereo
output is selected the left and right channels associated with the post-fader stereo
digital and analog monitor outputs become
active; the six channels of the post-fader
surround monitor digital and analog 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 digital
and analog 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
Model 76DA/77 User Guide
Studio Technologies, Inc.
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, 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 digital and analog monitor outputs
takes to reach the reference level value, it
will cause the reference level LED to flash!
Mute All
Pressing the mute all button causes the
output channels associated with the postfader surround and stereo digital and
analog monitor outputs to mute. The 4-digit
display indicates the mute condition by
showing four dashes (– – – –). The mute
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for Surround
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.
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!
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 digital and analog 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.
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.
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
Issue 1, September 2010
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Rotary Level Control
The rotary level control is used to manually
adjust the post-fader surround and stereo
digital and analog 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 24-step-per-revolution
mechanical encoder. The amount of level
change in dB per step (“click”) will depend
on how quickly the control is turned. When
rotated slowly, each step represents a 0.5dB 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 change in dB per
step. A little experimentation will allow the
user to acquire a good “feel” for how best
to use the control.
The reference level LED will flash when
the rotary level control sets the output level
to be the same as the stored reference
level. Whenever the rotary level control
attempts to set the output level for less
than –70.0 dB, the post-fader surround
and stereo digital and analog monitor
output channels will automatically mute.
Model 76DA/77 User Guide
Studio Technologies, Inc.
for Surround
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 digital and
analog monitor output levels. It’s also not
active whenever the reference level function is active, except if the auto reference
level off function has been enabled.
Channel 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 digital and analog monitor outputs, taking place electrically “after”
the input source selection delay, downmix,
and level control functions.
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. It is also used to select which solo
mode, normal or channel pop, is active.
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.
Model 76DA/77 User Guide
Studio Technologies, Inc.
The mute/solo button is also used to select
the solo mode, the choices being normal
or channel pop. Simply press and hold the
mute/solo button for a few seconds until
the LED associated with the solo mode
lights in the desired manner; steady to
indicate normal solo mode and flashing
for channel pop solo mode. Once the state
of the mode has changed as indicated by
the LED (steady-to-flashing or vice-versa)
the desired solo mode becomes active
and the mute/solo button can be released.
The selected solo mode will be maintained
even after the system is powered down
and subsequently powered up.
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 digital and analog
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 digital and analog 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.
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for Surround
Display in dB SPL
If the Model 77 is configured to display
the 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 C-weighted sound
pressure level.) When the reference level
button is enabled, or the rotary level control
is set so that the reference level has been
reached, the display will typically show
something in the range of 82 to 87 dB.
Assuming that the monitoring environment
has been correctly calibrated, this would
indicate that an average listening level of
85 dB, for example, had been achieved.
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 digital and analog 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
Issue 1, September 2010
Page 38
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 limited number of pushbutton switches,
LEDs, and a rotary level control for status
display and control. The two buttons, along
with associated LEDs, provide access to
the dim and reference level functions. A
rotary level control allows adjustment of
the post-fader surround and stereo digital
and analog monitor output levels. A status LED lights steadily whenever normal
Model 71 operation is taking place.
Any changes made using the Model 71’s
rotary level control and buttons will be
reflected in the appropriate LEDs and displays on all the connected Model 77 and
Model 71 units. And, as expected, changes
made using a Model 77 will be reflected in
the Model 71’s LEDs.
Rotary Level Control
The rotary level control is used to manually
adjust the post-fader surround and stereo
digital and analog monitor output levels.
Its operating characteristics are identical
to those of the Model 77 Control Console,
discussed earlier in this section.
Model 76DA/77 User Guide
Studio Technologies, Inc.
for Surround
Dim
The dim function allows the post-fader surround and stereo digital and analog 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.
Reference Level
The reference level button sets the postfader surround and stereo digital and
analog 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.
Technical Notes
Loss of Sync
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 digital
monitor output sample rate. The sample
rate will display as 32.0, 44.1, 48.0, 88.2,
96.0, 176.4, or 192.0, reflecting the impact
of the sync source rate and the Model
76DA’s configuration.
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.
The Model 76DA relies on an external
timing reference (sync) source for proper
operation. This can be in the form of an
AES3id, word clock, DARS (AES11),
bi-level video, or tri-level video reference
signal. In most cases the sync signal will
be connected to the sync input BNC connector located on the Model 76DA’s back
panel. Alternately, a configuration choice
allows the L/R input of the AES3id source
currently selected for monitoring to also
serve as the system’s timing reference.
Whenever a valid sync signal has been
connected to the Model 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.
Any time that a valid sync signal is not
connected to the Model 76DA the digital
monitor outputs will automatically revert
to an internally generated sample rate of
48 kHz with no digital audio content present. This audio “black” signal will allow
most connected equipment to continue
to function correctly, of course with no
meaningful audio signal present. The
analog monitor outputs will move to their
minimum output condition. As soon as a
valid sync signal is again connected to the
Model 76DA the digital monitor outputs will
automatically switch to their correct sample
rate and audio signals will again be present. The analog monitor outputs will return
to their normal signal levels.
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
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 digital and analog
Model 76DA/77 User Guide
Studio Technologies, Inc.
Power Down
Issue 1, September 2010
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for Surround
monitor outputs. A power-down circuit supplies the main microcontroller integrated
circuit with an indication that a power loss
is imminent. When this condition is detected the digital monitor outputs will switch to
silence (audio “black”) in preparation for a
complete loss of signal. Electromechanical
relays associated with the analog monitor
outputs will change to their mute state to
minimize the change of signal transients
reaching the connected inputs.
Power-Up Messages and
Error Codes
Upon mains power being applied to the
Model 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 76d
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. Should a problem be encountered
during power up one of two error codes
may show on the Model 77’s 4-digit
Issue 1, September 2010
Page 40
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 to the factory for
service. Note that for the vast majority of
StudioComm systems neither of these error
codes, especially Err2, will ever appear.
Sample Rate Conversion
(SRC)
Circuitry associated with stereo input C
can provide sample rate conversion (SRC)
capability. A digital audio signal connected
to that input can have its sample rate and
timing re-synchronized to match the Model
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
Model 76DA/77 User Guide
Studio Technologies, Inc.
for Surround
timing reference (sync) signal and, if required, a configured value. If a word clock,
DARS (AES11), or AES3id signal is the
designated sync source its rate will be the
Model 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 postproduction 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 digital monitor output can
be connected to other devices that find
need for the now-synchronized signal. In
some cases it may be useful to connect the
stereo input C direct digital monitor output
to the input of a signal router, allowing an
entire facility to access the signal.
Model 76DA/77 User Guide
Studio Technologies, Inc.
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 a +12 volt DC
power source for use by the control
console’s circuitry. The DC output is
current-limited to minimize the chance
that a short-circuit condition will damage
the Model 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.
“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 Model 71 units are
again connected. The control consoles
will go through their standard power-up
sequence and then normal operation will
resume.
Issue 1, September 2010
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Channel Status, User, and
Validity Bits
The non-audio bits that are part of the
AES3/AES3id digital monitor output channel data are actively controlled by the Model 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.
Issue 1, September 2010
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Model 76DA/77 User Guide
Studio Technologies, Inc.
for Surround
Specifications
Model 76DA Central Controller
General Audio:
Supported Sample Rates: 32, 44.1, 48, 88.2, 96,
176.4, and 192 kHz
Maximum Level: +24 dBu into 2000 (2 k) ohms
or greater
Frequency Response, Digital Inputs to Analog
Monitor Outputs: 10 Hz-20 kHz +0.0/–0.3 dB @
48 kHz sample rate; –3 dB @ 64 kHz
Distortion (THD+N): 0.004%, ref 1 kHz, +4 dBu
output
Word Length: 24 bits maximum
S/N Ratio: 89 dB, ref +4 dBu output
Internal Processing: 32 bits
Dynamic Range: greater than 109 dB
Input-to-Output Latency: one sample (e.g., 0.021
milliseconds @ 48 kHz sample rate)
Crosstalk: 98 dB at 1 kHz; 97 dB at 16 kHz,
ref –1 dBFS input
Digital Audio Inputs: five (18 audio channels)
Configuration: two surround (5.1) and three stereo
Connector: 25-pin D-subminiature female (DB-25F)
Type: AES3id-2001/SMPTE 276M (unbalanced
75 ohms/1 Vpp)
Connectors: BNC (per IEC 60169-8 Amendment 2)
Sample Rate Conversion (SRC):
Application: available on Stereo Input C
Input Sample Rate Range: 8 to 216 kHz, limited
to 1/6 to 6 times the output sample rate
Latency: 1 millisecond, nominal
Sync Source: configured to follow L/R of currently
selected input or signal connected to sync input
Sync Input:
Compatible Sources: word clock, DARS (AES11),
bi-level video, tri-level video
Jitter: 4 ns pp maximum
Connector: BNC (per IEC 60169-8 Amendment 2)
Termination: 75 ohms, selectable on/off
Configurable Delay: 0 to 340 milliseconds @
48 kHz sample rate (scales up or down depending
on actual sample rate)
Downmix:
Functions: 5.1 to stereo, stereo to mono
5.1 to Stereo: LS @ –3 dB summed with L;
RS @ –3 dB summed with R;
C @ –6 dB summed with L and R;
LFE @ –6 dB summed with L and R (if enabled);
C, LFE, LS, and RS monitor outputs mute
Stereo to Mono: L @ –3 dB summed with R @
–3 dB to C;
L, R, LS, RS, and LFE monitor outputs mute (for a
surround input this results in the C output being the
sum of L @ –3 dB, R @ –3 dB, C @ –3 dB, LFE @
–3 dB (if enabled), LS @ –6 dB, and RS @ –6 dB)
Control Console Interface:
Type: RS-485, 115.2 kbit/s, 8-1-N
Polling Interval: 50 milliseconds
Digital Monitor Outputs: 16 (8 pairs)
Configuration: organized as two surround (5.1)
and two stereo
Power: 12 volts DC, 500 milliamperes maximum
Dynamic Range: 135 dB
Remote Control Inputs: 2
Functions: remote mute all, remote dim
Type: AES3 (110 ohms/5 Vpp) or AES3id/SMPTE
276M (75 ohms/1 Vpp), selectable
Connector: 25-pin D-subminiature female (DB-25F)
Analog Monitor Outputs: 8
Configuration: organized as one surround (5.1)
and one stereo (2-channel)
Type: electronically balanced, source impedance
200 ohms
Nominal Level: +4.0 dBu @ –20 dBFS input
source and level control at maximum setting
Model 76DA/77 User Guide
Studio Technologies, Inc.
Connector: 9-pin D-subminiature female (DE-9F)
Type: +5 V logic, activates on closure to system
common
Connector: 9-pin D-subminiature female (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)
Issue 1, September 2010
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Dimensions:
19.00 inches wide (48.3 cm)
1.72 inches high (4.4 cm)
7.00 inches deep (17.8 cm)
Mounting: one space (1U) in a standard 19-inch
rack
Weight: 6.2 pounds (2.8 kg)
Model 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 D-subminiature female (DE-9F)
Dimensions (Overall):
7.20 inches wide (18.3 cm)
2.20 inches high (5.6 cm)
5.40 inches deep (13.7 cm)
Weight: 1.7 pounds (0.8 kg)
Model 71 Control Console
Application: up to three Model 71 Control
Consoles can be connected to a Model 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 D-subminiature female (DE-9F)
Dimensions (Overall):
3.20 inches wide (8.1 cm)
2.20 inches high (5.6 cm)
4.10 inches deep (10.4 cm)
Weight: 0.8 pounds (0.4 kg)
Specifications and information contained in this
User Guide subject to change without notice.
Issue 1, September 2010
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Model 76DA/77 User Guide
Studio Technologies, Inc.
for Surround
Appendix A—Connection Pin-Out
Charts
Connections
TASCAM® Signal
Channel High (+)
Signal
Low (–)
Shield
Connections
Signal
High (+)
Signal
Low (–)
Shield
Pre-Fader L/R
1
24
12
25
Surround L
24
12
25
Pre-Fader C/LFE
2
10
23
11
Surround R
10
23
11
Pre-Fader LS/RS
3
21
9
22
Surround C
21
9
22
Stereo Input C Direct
4
7
20
8
Surround LFE
7
20
8
Post-Fader L/R
5
18
6
19
Post-Fader C/LFE
6
4
17
5
Surround LS
18
6
19
Post-Fader LS/RS
7
15
3
16
Surround RS
4
17
5
Post-Fader Stereo
8
1
14
2
Stereo L
15
3
16
Stereo R
1
14
2
Notes: 1) All signals transformer-coupled digital audio;
selectable for AES3 or AES3id 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.
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.
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 Analog Monitor Outputs
Connections for Monitor Outputs
Signal
Data + (RS-485/RS-422)
Data – (RS-485/RS-422)
Pin
Direction
Signal
7
Not used
Data + (RS-485)
1
To/From Models 77/71
Not used
Data – (RS-485)
6
To/From Models 77/71
Data Shield
2
To/From Models 77/71
2
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 76DA is 9-pin D-subminiature
female (DE-9F). Connector uses 4-40 threaded inserts
for locking with mating plug.
Pin
Direction
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
Model 76DA/77 User Guide
Studio Technologies, Inc.
Issue 1, September 2010
Page 45
for Surround
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 AES3id: Signal with sample rate of 32, 44.1, 48, 88.2, 96, 176.4, or
192 kHz.
Bi-Level and Tri-Level Video: See table below.
Video Format
Video Format, continued
NTSC (“Black Burst”)
1035i/59.98 Hz
PAL (“Black Burst”)
1035i/60 Hz
525i/59.94 Hz
1080i/50 Hz
525p/59.94 Hz
1080i/59.94 Hz
625i/50 Hz
1080i/60 Hz
625p/50 Hz
1080p/23.98 Hz
720p/23.98 Hz
1080p/24 Hz
720p/24 Hz
1080p/25 Hz
720p/25 Hz
1080p/29.97 Hz
720p/29.97 Hz
1080p/30 Hz
720p/30 Hz
1080psf/24 Hz
720p/50 Hz
1080psf/23.98 Hz
720p/59.94 Hz
720p/60 Hz
Issue 1, September 2010
Page 46
Model 76DA/77 User Guide
Studio Technologies, Inc.
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