for Surround - Studio Technologies

for Surround - Studio Technologies
for Surround
Model 76D Central Controller and
Model 77 Control Console
User Guide
Issue 1, March 2009
This User Guide is applicable for systems consisting of:
Model 76D: serial number M76D-00151 and later;
Model 77: M77-00151 and later
© 2009 by Studio Technologies, Inc., all rights reserved
www.studio-tech.com
50230-0309, Issue 1
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for Surround
Table of Contents
Introduction ................................................................... 5
Installation .................................................................... 8
Configuration ................................................................15
Operation ......................................................................31
Technical Notes ............................................................37
Specifications ...............................................................41
Appendix A—Connection Pin-Out Charts ....................43
Appendix B—Sync Sources .........................................44
Model 76D/77 User Guide
Studio Technologies, Inc.
Issue 1, March 2009
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for Surround
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Model 76D/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
76D 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 (2-channel) audio
material has become a day-to-day reality,
the ability to simply and effectively monitor
these sources is imperative for recording,
post-production, and broadcast facilities.
And with an “all-digital” world now upon
us, additional monitoring challenges have
arisen. Studio Technologies has addressed
these needs with the StudioComm for Surround Model 76D Central Controller and the
Model 77 and Model 71 Control Consoles.
With the all-digital audio inputs and outputs,
support for multiple user control surfaces,
and 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, multiple preand 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.
An all-digital StudioComm for Surround
system starts with the Model 77 Control
Console. It’s the system’s “command center”
and is designed to reside at an operator’s
location, allowing fingertip selection of
all monitoring functions. Numerous LED
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Studio Technologies, Inc.
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 level control,
dim, and reference level.
While many installations will use only one
Model 77 Control Console, up to a total of
four Model 77 or Model 71 Control Consoles can be connected to a Model 76D
Central Controller. This provides multiple
users with full control over a facility’s monitor system. Making installation simple, the
Model 76D provides power for all connected Model 77 or Model 71 units.
The core of this StudioComm for Surround
system is the Model 76D Central Controller. The one-rack-space unit contains all
the audio input, output, processing, and
support circuitry. The Model 76D provides
two surround (5.1) and three stereo audio
inputs. These unbalanced digital inputs are
AES3id/SMPTE 276M-compliant; sources
of this type are ubiquitous in most postproduction and broadcast environments.
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
source to be monitored. Up to 340 milliseconds of input delay can be selected to
compensate for processing delays in an
associated video path. For synchronization
with a master timing reference the Model
76D allows direct connection of a word
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for Surround
clock, DARS (AES11), AES3id, bi-level
video, or tri-level video signal.
Great care was taken in designing the
system’s architecture, ensuring that the
character of the audio input signals is
preserved. All audio processing is performed in 32 bits using a high-speed
field-programmable gate array (FPGA)
integrated circuit. A dynamic range of
greater than 123 dB is provided with less
than 1 dB of input-to-output noise added.
Two surround (5.1) and two stereo monitor outputs are provided. The post-fader
surround and stereo monitor outputs are
intended for connection to monitor loudspeaker systems. The pre-fader surround
monitor output can be used with metering
systems that require signals that aren’t
impacted by level control or other monitoring functions. The stereo input C direct
monitor output allows an installation to
directly access the SRC capabilities.
The Model 76D occupies one space (1U)
in a standard 19-inch rack. Digital audio
signals are interfaced with the Model 76D
using nine BNC connectors. Monitor output signal connections are made using
one 25-pin D-subminiature connector. One
9-pin D-subminiature connector is used
to connect the Model 76D 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 76D, with an acceptable range of
100 to 230 volts, 50/60 Hz.
For installation flexibility the outputs can
be configured for compatibility with equipment that requires AES3 (“balanced”)
or AES3id (“unbalanced”) digital audio signals. When selected for AES3 compatibility
the output impedance is 110 ohms with
a 5 volts peak-to-peak (Vpp) level. For
AES3id operation the impedance is
75 ohms and the level is 1 Vpp.
Figure 1. Model 76D Central Controller Front Panel
Control console
status LED
Sync status
LED
Figure 2. Model 76D Central Controller Back Panel
AC mains input
connection
To/from
Models 77 &
71 Control
Consoles
RS-485 and
remote control
inputs
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Digital
monitor
output
connections
Sync
Input
connection
Surround Input B
connections
Stereo
Input C
connection
Stereo Input A and
Stereo Input B
connections
Surround Input A
connections
Model 76D/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
Additional Details
The Model 77 provides five buttons and
associated LEDs for selection of the surround and stereo input sources to be monitored. While in most cases only one input
source will be monitored at a time, stereo
input C can be selected for simultaneous
monitoring with one of the two surround
or other two stereo inputs. This allows
the two selected inputs to be combined
(“summed”).
The post-fader surround and stereo monitor output levels can be controlled by way
of a large, easy-to-use rotary control. The
control, actually a digital encoder, allows
level selection in precise 0.5-dB steps. The
auto mute all function causes the postfader surround and stereo monitor output
channels to automatically mute whenever
the output level is set to its minimum position. Using the reference level function, the
post-fader surround and stereo monitor
output levels can be set to a pre-configured value. This is provided for audio-withpicture applications that require a specific
Model 76D/77 User Guide
Studio Technologies, Inc.
monitor output level. The reference level is
easily configured by taking an electronic
“snapshot” of the desired monitor output
level. For operator confirmation a 4-digit
LED readout can display the level of the
post-fader surround and stereo monitor
output channels. To match the needs of
a facility, it can be configured to display
either the attenuation level or the sound
pressure level (SPL).
The dim function allows the post-fader
surround and stereo monitor output levels
to be reduced by a fixed dB amount. The
dim level is configured from among four
available values. A mute all function allows
all post-fader surround and stereo monitor output channels to be simultaneously
muted. The channel mute/solo section provides individual 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
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unique aid in monitoring audio material.
Channel pop solo allows the level of a
single channel to be raised while the level
of the other channel is reduced. This helps
to emphasize the content on one channel
without fully muting the others. Broadcast
applications can benefit from the channel
pop solo mode allowing, for example, the
center channel to be highlighted while still
maintaining some level on the other channels. The amount of level increase—the
“pop”—as well as the amount of attenuation can be configured to meet the needs
of specific applications or users.
Two functions allow the input sources to be
checked for level or phase inconsistencies.
The 5.1 to stereo downmix function is used
to create a stereo signal from the selected
surround (5.1) source. The stereo to mono
downmix function allows audio on the left
and right channels to be added (summed)
and monitored on the center output channel. The two downmix functions can be
simultaneously enabled, allowing a surround source to be checked for mono compatibility. The downmix functions always
impact the post-fader surround and stereo
monitor outputs. A configuration setting
allows the pre-fader surround monitor output to be selected for pre- or post-downmix
operation.
For flexibility, the StudioComm for Surround system is designed to easily integrate with equipment such as production
intercom systems, on-air or recording tally
signals, and audio consoles. Two remotecontrol input functions are provided: mute
all and dim. 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 monitor outputs.
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Installation
In this section you will be installing the
Model 76D Central Controller in an equipment rack. Connections to the audio inputs
and monitor outputs will be made. 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
76D. AC mains power will be connected to
the Model 76D. For advanced applications
up to three additional Model 77 or Model 71
Control Console units can be connected to
the Model 76D.
System Components
The main shipping carton contains one each
of the following: Model 76D Central Controller, Model 77 Control Console, 9-pin D-sub
interconnecting cable, and user guide. Also
included in the shipping carton is a North
American-standard AC mains cord. Your
dealer or distributor should provide an AC
mains cord appropriate for destinations outside of North America. Any additional Model
77 or Model 71 Control Consoles will be
shipped in separate cartons.
Mounting the Model 76D
The Model 76D Central Controller requires
one space in a standard 19-inch (48.3 cm)
equipment rack. Select a location that is
convenient for making connections to the
audio signals as well as interfacing with
the first (or only) Model 77 Control Console.
A cable is supplied to connect the Model
76D to the Model 77. If the needs of a
specific installation dictate, an alternatelength interconnecting cable can be fabricated and used. Secure the Model 76D
into the equipment rack using two mounting
screws per side.
Model 76D/77 User Guide
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for Surround
Audio Connections
Audio connections are made by way of nine
BNC jacks and a 25-pin D-subminiature
connector. All the connectors are located
on the Model 76D’s back panel. Refer to
Figure 2 for a detailed view of the back
panel.
Audio Inputs
Two surround (5.1) and three stereo
(2-channel) digital audio sources can be
connected. All sources can be monitored
using the pre- and post-fader surround and
post-fader stereo monitor output channels.
A one-to-one relationship is maintained
between the input channels and output
channels, i.e., left input to left monitor output, right input to right monitor output,
center input to center monitor output, etc.
(Of course this won’t be true in the case
where the user has enabled the 5.1 to
stereo downmix function.) Stereo input C
is also routed to the stereo input C direct
monitor output.
The audio inputs support digital audio signals with sampling rates of up to 192 kHz
and a word length (depth) of up to 24 bits.
However, all the connected signal sources
must maintain a common sample rate and
timing reference. Having all signals “locked”
together ensures proper handling by the
Model 76D’s all-digital signal path.
There is, however, an exception worth noting. Circuitry associated with stereo input C
has sample rate conversion (SRC) capability, allowing virtually any digital audio signal
to be connected. Refer to the Technical
Notes section of this guide for a detailed
review of the SRC capability. A signal connected to stereo input C can have an independent sample rate and timing reference
and still be monitored correctly.
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Studio Technologies, Inc.
Nine BNC jacks (female) on the Model
76D’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 76D’s
inputs if external coupling transformers
(“baluns”) are utilized. These impedancematching (110 ohms to 75 ohms) and
level-attenuation transformer assemblies
typically provide a 3-pin female XLR connector on their input and a female BNC
connector on their output.
Monitor Outputs
The 25-pin D-subminiature connector
labeled Digital Monitor Outputs provides
access to the Model 76D’s 16 channels
of digital audio: pre-fader surround, postfader surround, post-fader stereo, and
stereo input C direct monitor outputs. The
pre-fader surround monitor output channels are intended for connection to metering or monitoring equipment that requires
uninterrupted full-level signals. The postfader surround monitor output channels
are intended to connect to the main 5.1
loudspeaker system incorporated in a facility. The post-fader stereo monitor output
is provided to support a separate set of
stereo monitor loudspeakers. The stereo
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input C direct monitor output is essentially
a unity gain copy of the signal connected
to stereo input C. However, the signal does
pass through the sample rate conversion
(SRC) and input delay circuitry. The impact
made by these functions will depend on the
specific input signal and the Model 76D’s
configuration settings.
one pin remains unused. Each set of three
pins provides an independent interface.
In the analog world this would allow eight
audio signals to be transported. But with
AES3/AES3id digital audio signals this allows support for 16 audio channels; eight
interfaces each consisting of two audio
channels.
It’s important to reiterate that all the monitor
outputs are digital; the Model 76D doesn’t
provide any analog outputs! This requires
that all equipment connected to the Model
76D’s monitor outputs provide digital input
capability.
A wiring assembly prepared for the Model
76D’s monitor outputs, when configured
for AES3 (110 ohms/5 Vpp), would be
identical to that of a DA-88-style output
assembly. An assembly of this type would
have a male 25-pin D-subminiature connector (DB-25M) on one end and eight
3-pin male XLR connectors on the other.
A wiring assembly prepared for the Model
76D’s digital monitor outputs, when set for
AES3id (75 ohms/1 Vpp), would typically
have eight BNC plugs attached.
For flexibility the monitor outputs are
transformer-coupled and can be configured
to act as AES3 or AES3id digital audio
sources. The monitor outputs are configured
as groups with separate choices available
for the pre-fader surround/stereo input C
direct group and post-fader surround/postfader stereo monitor output group. When a
group is set for AES3 (110 ohms/5 Vpp) the
signals are compatible with AES3 interfaces.
Signals of this type are normally interconnected using 3-pin XLR connectors. When
a group is configured for AES3id (75 ohms/
1 Vpp) the source impedance and signal
level are compatible with the requirements
of AES3id interfacing. These signals are
typically interconnected using BNC connectors. For details on how a Model 77 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;
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For compatibility with AES3 balanced
digital audio signals connect the D-sub’s
+ terminal as signal high and the – terminal as signal low. In most applications a
3-pin XLR plug (male) will be used. In this
case the + signal would go to pin 2 of the
XLR, the – terminal to XLR pin 3, and the
shield terminal to XLR pin 1.
For compatibility with AES3id unbalanced
digital audio signals connect the D-sub’s
+ terminal as signal high, and both the
– and shield terminals as the signal low/
shield. When terminating to a BNC plug
the D-sub’s + terminal should connect to
the center pin; the – and the shield connections should go to the “body” of the
BNC plug. For optimal operation, it is best
to connect both – and shield together directly on the D-sub plug, rather than at
the BNC end of the interface assembly.
Note that the output circuitry is transformer-coupled so it is possible to just connect
Model 76D/77 User Guide
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for Surround
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 76D’s
D-sub connector use 4-40 threads. This
complies with the original design standard
for D-sub connectors.
Pre-Fader Surround Monitor Output
The pre-fader surround monitor output
channels are intended to connect to metering, measurement, test, or other signal
monitoring equipment that require uninterrupted, full-level digital audio signal sources.
Post-Fader Surround Monitor Output
The post-fader surround monitor output
channels are designed for connection to
audio amplifiers associated with monitor
loudspeakers or to the inputs of loudspeakers that contain integrated amplifiers.
Connections
TASCAM® Signal
Channel High (+)
Signal
Low (–)
Shield
Pre-Fader L/R
1
24
12
25
Pre-Fader C/LFE
2
10
23
11
Pre-Fader LS/RS
3
21
9
22
Stereo Input C Direct
4
7
20
8
Post-Fader L/R
5
18
6
19
Post-Fader C/LFE
6
4
17
5
Post-Fader LS/RS
7
15
3
16
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 76D is 25-pin
D-subminiature female (DB-25F). Installer must
provide male (DB-25M). Connector uses 4-40
threaded inserts for locking with mating plug.
3) Wiring scheme follows TASCAM DA-88 convention.
Standard DA-88-type wiring harnesses are directly
compatible, with the exception of 4-40 screw threads
being required.
Post-Fader Stereo Monitor Output
The post-fader stereo monitor output
channels are intended to support a stereo
loudspeaker system, either connecting to
an amplifier associated with a set of loudspeakers or directly to a set of amplified
speakers.
Stereo Input C Direct Monitor Output
The stereo input C direct monitor output
is intended for use in site-specific applications. It provides an uninterrupted, full-level
digital audio signal source.
Sync Input
An external timing reference signal must
be connected to the Model 76D. This synchronization (“sync”) signal must maintain
a stable relationship between itself and the
connected digital audio signals. The actual sync source can be in one of several
forms: word clock, DARS, AES3id, bi-level
video, or tri-level video. The source of the
Model 76D’s sync reference will, in most
cases, be a dedicated sync signal connected to the unit’s sync input. Alternately,
the AES3id-compatible digital audio source
connected to the L/R input of surround A
can also serve as the sync reference. A
configuration choice, described later in
this user guide, is used to select the actual
sync source to be utilized. In this section
of the user guide details will be provided
regarding connection of a dedicated sync
signal to the sync input. This is the recommended method and in most cases should
be utilized.
An overview of the various compatible
timing reference signals might prove
worthwhile. Word clock is a digital signal
that is locked in phase and frequency to
the sample rate of the associated digital
Figure 4. Connections for Monitor Outputs
Model 76D/77 User Guide
Studio Technologies, Inc.
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audio sources. DARS (digital audio reference source) is a timing signal compliant
with the AES11 standard. It’s sometimes
referred to as “AES3-black.” Technically it
is similar to an AES3 or AES3id signal but
is generated specifically as a timing reference signal. Bi-level video sync signals are
typically provided to support NTSC or PAL
broadcast applications, although they’re
also used by some later-generation equipment. Tri-level sync signals are primarily
associated with facilities that support highdefinition (HD) video equipment. These
tri-level signals can be found at numerous
rate combinations, configured to allow for
compatibility with the various video formats. With the wide range of allowable
sync sources proper Model 76D operation
should be easy to obtain. Extensive testing
has been done using many different sync
source types and rates. Interested users
can refer to Appendix B of this user guide
for details.
The external sync reference source should
be connected to the sync input BNC connector located on the Model 76D’s back
panel. For flexibility the input can be configured to be high-impedance (“floating”) or
terminated with an impedance of 75 ohms.
A sync source that is dedicated for use by
the Model 76D’s sync input will typically
have input termination enabled. If the sync
signal connected to the Model 76D is being connected (“multed”) to other inputs it
may be desirable for the termination to be
disabled. A general “rule of thumb” is that
termination should be applied only at the
location of the last physical device using
a sync signal. Refer to the Configuration
section of this guide for details on how to
select the desired termination settings.
Remote Control Inputs
Support is provided for two remote control input functions: remote mute all and
remote dim. The inputs use logic gates,
“pulled up” to +5 volts DC by way of resistors, which are active whenever they are
brought to their logic low state. Inputs of
this type are commonly referred to as GPI
inputs. While the input circuitry is protected
from over-current and static (ESD) discharge, care should be taken to prevent
nasty signals from reaching them. The
inputs are active only when held in the low
state; they can’t be configured to change
state (“latch”) in response to a logic pulse.
A 9-pin D-subminiature connector is used
for the remote control inputs. Refer to
Figure 5 or Appendix A for the exact connection details. Note that pin 4 (remote
common) connects to the Model 76D’s
internal circuit common connection as
well as the Model 76D’s chassis and
mains earth connections. Figure 5 also
shows two spare remote control inputs
(pins 8 and 9). These are provided for
future applications and should remain
unconnected. This connector also allows
Signal
Pin
Direction
Data + (RS-485/RS-422)
7
Not used
Data – (RS-485/RS-422)
2
Not used
Data Shield
1
Shield
Remote Mute All
5
Input
Remote Dim
6
Input
Remote Spare 1
8
Input
Remote Spare 2
9
Input
Remote Input Common
4
Common
Note: Connector type on Model 76D is 9-pin D-subminiature
female. Connector uses 4-40 threaded inserts for
locking with mating plug.
Figure 5. Connector Pin Out for Remote Control
Inputs
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Model 76D/77 User Guide
Studio Technologies, Inc.
for Surround
access to an RS-485 data interface. This
interface is not supported in the Model 76D
and, as such, pins 7 and 2 should remain
unterminated.
Connecting the Model 76D 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 76D
Central Controller. This is used to interface
the unit with Model 77 Control Consoles.
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 connectors on each end is used to interconnect
the Model 76D with the Model 77 units. A
cable is included in the shipping carton. The
cable implements all nine connector pins in
a one-to-one manner.
Should an interconnecting cable of a different length be required there’s no problem for
one to be fabricated and used. While it can
be wired in a one-to-one fashion supporting all nine pins, only four connections are
required: pin 1 (data +), pin 6 (data –), pin 4
(DC +), and pin 9 (DC –). The Model 76D’s
connector pin-out scheme was designed to
allow creation of an interconnecting cable
which uses commonly available 2-pair audio
cable. This cable, consisting of two twisted
pairs each with an individual shield, is typically sleek, flexible, and available in many
colors. One pair and shield can be used for
the data connections while the other pair
and shield can be used for the DC connections. This implementation has the advantages of providing a shield for the data path
and a more robust common connection (two
conductors including the shield) for the DC
power circuit. Refer to Figure 6 or Appendix
A for details.
Model 76D/77 User Guide
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Signal
Pin
Direction
Data + (RS-485)
1
To/From Models 77/71
Data – (RS-485)
6
To/From Models 77/71
Data Shield
2
To/From Models 77/71
DC + (12 V)
4
To Models 77/71
DC – (12 V Return)
9
To Models 77/71
DC Power Shield
5
To/From Models 77/71
Note: Connector type on Model 76D is 9-pin D-subminiature
female (DE-9F). Connector uses 4-40 threaded inserts
for locking with mating plug.
Figure 6. Connections between Model 76D and
Model 77 and Model 71
A few simple calculations are required to
determine the maximum cable length when
connecting a Model 77 to a Model 76D.
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 76D to the Model 77. The Model
76D supplies 12 volt DC with a maximum
current of 500 milliamperes.
The Model 77 requires a minimum of
9 volts DC, 100 milliamperes maximum
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 76D supplies 12 volts and the
Model 77 requires 9 volts minimum, this
directly leads to a 3 volt DC maximum
drop due to the interconnecting cable. Using Ohm’s law it’s quite easy to determine
whether the selected cable will support the
desired interconnection length. Calculate
the voltage drop by multiplying the total
resistance (in ohms) of the proposed cable
by 0.1 (the Model 77’s maximum required
current in amperes). Remember to include
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the resistance in both the DC + and
DC – wires in the figure for the total resistance. If it’s greater than 3 volts your cable
is too long or the wire gauge is too small.
Additional Control Consoles
Some installations may benefit from the
Model 76D’s ability to be controlled by additional control consoles. As expected, at
least one Model 77 Control Console must
be connected to a Model 76D 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 76D.
When connecting multiple control consoles
to a Model 76D all nine pins of each interconnecting cable can be connected in
parallel (“multed”). This will electrically
mult the data and 12 volt DC power signals
between all the units. A custom cable
implementation requires just four pins to
be connected: pin 1 (data +), pin 6 (data –),
pin 4 (DC +), and pin 9 (DC –).
To make installation simple, a “bus” cable
assembly can be created using a short
length of ribbon cable with one male and
multiple female 9-pin D-subminiature insulation-displacement connectors attached.
Then standard 9-pin cables can link the
control consoles with the connectors on
the bus cable.
Refer to the previous paragraphs of this
user guide where the issues involving
Model 76D to Model 77 cable length are
discussed. Note the maximum 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.
Issue 1, March 2009
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AC Mains Power
The Model 76D operates directly from
AC mains power of 100 to 230 V, 50/60 Hz.
Being a “universal input” device, there are
no switches to set or jumpers to install
to match a location’s mains voltage. The
unit uses a 3-pin IEC 320 C14-type inlet
connector to mate with a detachable mains
cord. All units are supplied with a mains
cord that has a North-American standard
plug (NEMA 15L) on one end and an IEC
320 C13 socket on the other. Units bound
for other destinations require that the appropriate cord be used. The wire colors
in the mains cord must conform to the
internationally recognized color code and
should be terminated accordingly:
Connection
Neutral (N)
Line (L)
Protective Earth (E)
Wire Color
Light Blue
Brown
Green/Yellow
Safety Warning: The Model 76D does
not contain an AC mains disconnect
switch. As such, the AC mains cord
plug serves as the disconnection
device. Safety considerations require
that the plug and associated outlet be
easily accessible to allow rapid disconnection of AC mains power should
it prove necessary.
As soon as mains power is applied
the Model 76D 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 76D’s main logic
device. After just a few seconds normal
operation can commence and the LEDs
will perform their intended functions. Once
Model 76D/77 User Guide
Studio Technologies, Inc.
for Surround
normal operating data is being interchanged with the one or more connected
Model 77 or Model 71 Control Consoles
the control console status LED will light.
The sync status LED will light if a recognized sync source has been connected.
The sync status LED will flash if a valid
sync source is not recognized.
Also upon application of mains power, all
connected Model 77 units will go through
a power-up sequence, lighting each of its
LEDs in succession. Using its 4-digit display, each Model 77 will then momentarily
display its address, its software version,
and the software versions of the associated Model 76D. At this point normal system
operation can begin.
All connected Model 71 units will also go
through a power-up sequence after mains
power is applied to the Model 76D. Each
of the units’ three status LEDs will light
momentarily. After the three status LEDs
have been lit, the device address will be
shown briefly using the dim and reference
level LEDs as shown in Figure 8. When
this is complete the Model 71 will enter the
normal operating mode and its status LED
will light if communications are established
with the Model 76D. If the Model 71’s status LED does not light check to see if there
is a device address conflict among all connected control consoles and that all cables
are connected properly.
Should an error be detected during the
start-up process the two status LEDs on
the Model 76D 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.
Configuration
After the physical installation has been
completed it’s important that the system’s
configuration options be carefully reviewed.
In most cases one or more of the operating
parameters will need to be revised to meet
the needs of the specific installation. Many
of the configuration parameters will impact
the signal flow in to and out of the Model
76D 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. One
configuration choice is available for each of
the connected Model 71 Control Consoles.
Configurable Parameters
Many StudioComm functions can be
configured to meet the exact needs of an
installation. The Model 77 Control Console
is used to display and select the desired
system configuration. Here’s an overview
of what can be configured:
• Model 77 Device Address
• Stereo Input C Sample Rate Converter
• Post-Fader Stereo Output
• Sync Type
• Sync Input Termination
• Audio-Synced-to-Video Sample Rate
• Monitor Output Types
• Reference Level
• Overall Display Mode
• Reference Level in dB SPL
• Auto Reference Level Off
• Dim Level
Model 76D/77 User Guide
Studio Technologies, Inc.
Issue 1, March 2009
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for Surround
• Remote Inputs
• Input Delay
• LFE Downmix Mode
• Pre-Fader Surround 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 the 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 76D into
their configuration modes. Other connected Model 77 and Model 71 units will
enter a standby mode. When the Model
76D enters its configuration mode it will
immediately mute the monitor outputs as
a speaker protection measure. When a
Model 77 enters the configuration mode
its array of buttons and LEDs no longer
perform their normal functions, instead
they are used to display the operating
parameters and reflect configuration
changes as they are made.
As a user aid, a Model 77 that has entered
the configuration mode will have its mute
and solo LEDs (associated with the channel mute/solo section) light in an alternating manner. Other connected Model 77
units will indicate that they have entered
the standby mode by simultaneously flashing their mute and solo LEDs.
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To leave the configuration mode and return
the system to normal operation requires
one last action on the Model 77 unit that’s
in its configuration mode. Again press and
hold configure button for two seconds.
Note that configuration changes are stored
in nonvolatile memory only after the configuration mode has been exited.
Our apologies to those of you who find
the configure button a pain to use, but it’s
supposed to be that way! Seriously, the top
of the button is slightly recessed from the
back panel, making it harder to accidentally activate. We didn’t want normal operation to cease because someone pushed a
Model 77 into a “rats nest” of schedules,
memos from management, and empty
coffee cups! But a firm press with the
fleshy part of an index finger should do
the trick.
There is no problem frequently “tweaking” the system’s operating parameters
to achieve the desired performance. The
configuration data is stored in nonvolatile
memory, which is rated for thousands of
read and write cycles and a retention time
in tens of years. Note that memory integrated circuits are located in the Model
76D Central Controller as well as the
Model 77 and Model 71 Control Consoles.
Only the individual device address is
stored in each Model 77 and Model 71.
All other configuration parameters are
stored in the Model 76D.
Model 77 Device Address
A unique device address must be assigned
to each Model 77 that is connected to a
Model 76D. 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,
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Studio Technologies, Inc.
for Surround
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)
of connected digital audio signals. The
acceptable input range for sample rate
conversion is very wide, but is dependent
upon the output sample rate. With an output sample rate of 48 kHz any signal with
a sample rate over a range of 8 to 216 kHz
can be properly monitored by the system.
This capability can be especially useful with signals that are not synchronized
in respect with the others connected to
the Model 76D, 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 Output
In addition to the post-fader surround
monitor output, a separate post-fader
stereo monitor output is also provided.
By default this stereo output can be enabled by an operator. In applications where
Model 76D/77 User Guide
Studio Technologies, Inc.
stereo monitor loudspeakers are not connected to the post-fader stereo monitor
output, the output can be disabled. This
can minimize confusion, preventing an operator from attempting to select the postfader stereo monitor output.
Sync Type
The Model 76D requires that the designated sync (external timing reference) signal
be defined. Three of the choices—word
clock, DARS, and video—are associated
with a signal that is connected to the sync
input BNC connector. The fourth choice
allows an AES3id-compatible digital audio
signal connected to the L/R input of surround input A to serve as the sync source.
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 76D then
enabling termination is typically appropriate. If the sync source is being “shared” by
multiple inputs then care must be taken so
that the signal is only terminated by one
device.
Audio-Synced-to-Video
Sample Rate
If a video sync signal is being used as the
Model 76D’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.
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Pre-Fader Surround/Stereo
Input C Direct Monitor Output
Type
To meet the needs of a specific installation
the nominal impedance and level characteristic of the pre-fader surround and
stereo input C direct monitor outputs can
be selected. They are selected as a group;
configuration of individual outputs is not
provided. If the output signals are going
to be connected to balanced AES3 inputs
then the setting that provides a source
impedance of 110 ohms with a nominal
5 Vpp level would be appropriate. If the
output signals are going to be connected
to unbalanced AES3id inputs then the
setting that provides a 75 ohm source
impedance and a nominal output level
of 1 Vpp would be correct.
Post-Fader Surround/Stereo
Monitor Output Type
The source impedance and output level of
the post-fader surround and stereo monitor outputs, as a group, can be configured.
The information previously provided concerning the pre-fader surround and stereo
input C direct monitor output type also
applies to these outputs.
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 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:
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1. Set up a precision sound pressure
level (SPL) measuring device at the
desired listening location.
2. Place the StudioComm system in the
normal operating mode, not the configuration mode. Be certain that the dim,
mute all, reference level, and downmix
functions are not active. The remote
mute all and remote dim functions
must also not be active.
3. Use the Model 77 Control Console to
select the input source that contains
the desired reference signal source,
e.g., pink noise.
4. Observing the SPL meter, adjust the
Model 77’s rotary level control until the
desired loudspeaker system reference
level has been reached.
5. Being careful not to disturb the position of the rotary level control, enter the
configuration mode by pressing and
holding the configuration button located on the Model 77’s back panel.
6. Once the configuration mode has been
entered, all the monitor outputs 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.
Model 76D/77 User Guide
Studio Technologies, Inc.
for Surround
The new reference level is now stored
in the Model 76D’s nonvolatile memory.
Only by repeating the entire procedure
can the value be changed.
Once the configuration mode has been exited, the monitor outputs will again become
active. Confirm that the correct level has
been stored by pressing the reference level
button. The SPL meter should display the
desired level. If not, repeat the calibration
procedure to achieve the desired goal.
You might wonder why you have to press
and hold the reference level button for
five seconds before the selected value is
recognized. This is provided specifically so
that unauthorized users won’t accidentally
change the reference level while they experiment with the configuration mode. Only
if you know the “secret” will you be able to
store a new value.
Overall Display Mode
The Model 77’s 4-digit numeric display
can be configured to display the post-fader
surround and stereo 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 moved in
the counterclockwise direction the display
will show negative values, reaching –70.0
before the full mute function automatically
mutes the outputs.
In the SPL mode the display can be configured to allow the output level to be
presented to users in terms of the actual
sound pressure level (SPL). Used in conjunction with the reference level in dB SPL
configuration and the stored reference
Model 76D/77 User Guide
Studio Technologies, Inc.
level, SPL mode allows a user to see a visual representation of the SPL level that is
present in the listening environment. While
it takes a little more care to correctly implement the SPL display mode, it can offer
an enhanced experience for StudioComm
users.
Reference Level in dB SPL
The reference level in dB SPL configuration allows a specific SPL value to be
associated with the stored reference level
value. In this way whenever the post-fader
surround or stereo monitor output is at
the 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.
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Dim Level
LFE Downmix Mode
The dim function is used to reduce the postfader surround and stereo monitor output
levels by a preset amount. The reduction is
in dB relative to the post-fader surround and
stereo monitor outputs’ current level. There
are four dim level values available: –10.0,
–15.0, –20.0, and –25.0 dB.
By default, when the 5.1 to stereo downmix function is active the LFE channel
associated with a surround input is muted.
This removes LFE content from the “downmixed” signal. In most applications this is
appropriate. However, for special situations
a configuration mode allows the LFE channel to be part of the downmix signal flow.
When the LFE downmix mode is enabled,
if surround input A or B is the active input
and the 5.1 to stereo downmix function is
active, the LFE signal level is reduced in
level by 6 dB and added to both the left
and right output channels. As expected,
even when the LFE downmix mode is active the LFE output channel will still mute
when 5.1 to stereo downmix is active.
Remote Mute All
Two configuration choices are associated
with the remote mute all function: disabled
and enabled. To utilize the remote mute all
function simply requires you to select the
enabled setting.
Remote Dim
Two configuration choices are associated
with the remote dim function: disabled and
enabled. To utilize the remote dim function
simply configure it for enabled.
Input Delay
A time delay can be added to the input signals, allowing compensation for delays that
may be present on associated video signals.
The selected time delay applies to all input
signals and cannot be applied selectively.
The configured delay time is referenced
to a sample rate of 48 kHz. In the case of
input signals with a sample rate of 48 kHz
the delay range is 0 to 340 milliseconds. For
other sample rates the time must be linearly
scaled. For example, for a sample rate of
96 kHz the actual time range is 0 to 170
milliseconds. In this case selecting a delay
of 120 on the Model 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.
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Pre-Fader Surround Monitor
Output Mode
The pre-fader surround monitor output can
be configured as to its place in the Model
76D’s signal flow. The choices are pre- or
post-downmix. In the pre-downmix mode
the output channels will not be impacted
by the state of the downmix functions.
This setting would be appropriate if the
pre-fader surround monitor outputs were
being routed to a storage system, routed
to another facility, etc. In this case the action of an operator enabling or disabling
the downmix functions won’t impact the
pre-fader surround monitor output signals.
If the post-downmix mode is selected the
pre-fader surround monitor outputs will
reflect the actions of the downmix functions. This choice would be correct if, for
example, level meters were connected to
the pre-fader surround monitor outputs. In
this scenario an operator would want to
visually observe the actions that the downmix functions impart on the signals.
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for Surround
Channel Pop Solo Mode
Offset Levels
Two parameters can be configured that
set how the channel pop solo function will
impact audio levels. The up offset level
sets the amount of increase (gain) that a
channel will experience when it is soloed
in the channel pop solo mode. The down
offset level sets the amount of decrease
(attenuation) that the non-soloed channels
will experience when a channel is active in
the channel pop solo mode.
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!
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Studio Technologies, Inc.
Issue 1, March 2009
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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.
Issue 1, March 2009
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Model 76D/77 User Guide
Studio Technologies, Inc.
for Surround
Configuration—Model 77 Device Address, Stereo Input C
Sample Rate Converter, and Post-Fader Stereo Output
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
output.
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 output
function. When
LED Surround
is lit the function
cannot be enabled. When LED
Stereo is lit the
function can be
enabled. Use the
button to change
the configuration.
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 output can be enabled.
Note:
The Model 77’s device address is the only parameter stored in the Model 77. All other parameters are stored
in the Model 76D.
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Issue 1, March 2009
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for Surround
Configuration—Sync Type, Sync Input Termination, AudioSynced-to-Video Sample Rate, and Monitor Output Types
This LED displays the configuration
of the sync input termination. LED
not lit means sync input is not terminated; LED lit means terminated with
75 ohms. Use the button to change
the configuration.
Use the Channel Solo C and LFE buttons to select the pre-fader surround/
stereo input C direct monitor output
type. Use the buttons to change the
configuration. C LED lit means AES3id
(75 ohms/1 Vpp); LFE LED lit means
AES3 (110 ohms/5 Vpp).
Use the Channel Solo LS and RS
buttons to select the post-fader
surround/stereo 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
type, sync input
termination,
audio-synced-to
video-sample
rate, and monitor output types.
Use these buttons
to select sync type.
LED Surround B
lit means video
sync;
LED Stereo A lit
means DARS;
LED Stereo B lit
means word clock;
LED Stereo C lit
means sync to
surround input A.
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 type video.
Sync input terminated.
Audio-synced-to-video sample rate 48 kHz.
Pre-fader surround/stereo input C direct monitor output type AES3 (110 ohms/5 Vpp).
Post-fader surround/stereo monitor output type AES3 (110 ohms/5 Vpp).
Issue 1, March 2009
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Model 76D/77 User Guide
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 fully attenuated (minimum) post-fader monitor output level.
Note:
The 5-second button-press delay is a safety feature ensuring that the reference level will not be accidently
changed. To permanently store the new value, you must still exit the configuration mode.
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Issue 1, March 2009
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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.
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Model 76D/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, and 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.
Scale up or down for other sample rates.
–20 dB dim level.
Remote mute all enabled.
Remote dim enabled.
Input delay 0 ms.
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Studio Technologies, Inc.
Issue 1, March 2009
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for Surround
Configuration—LFE Downmix Mode and Pre-Fader Surround
Monitor Output Mode
These LEDs display the configuration of the
pre-fader surround monitor output mode.
LED L lit means outputs are pre-downmix;
LED R lit means outputs are post-downmix.
Use the buttons to change the configuration.
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 monitor
output modes.
Default:
LFE downmix disabled.
Pre-fader surround monitor outputs pre-downmix.
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Model 76D/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 76D/77 User Guide
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Issue 1, March 2009
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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 output can be enabled.
Sync type video.
Sync input terminated.
Audio-synced-to-video sample rate 48 kHz.
Pre-fader surround/stereo input C direct monitor output
type AES3 (110 ohms/5 Vpp).
Post-fader surround/stereo monitor output type
AES3 (110 ohms/5 Vpp).
Reference level set for fully attenuated (minimum)
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 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.
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Model 76D/77 User Guide
Studio Technologies, Inc.
for Surround
Model 71 Control Console
Configuration
The only configuration choice available on
a Model 71 is its device address. It must
be selected so as not to conflict with the
device address of any other connected
Model 71 or Model 77 Control Console.
The choices are A1, A2, A3, and A4. All
Model 71 units have a default device address of A4 while the Model 77’s have a
default device address of A1. This ensures
that, in most cases, no change will have to
be made.
A small button is located on the back of
each Model 71 Control Console, adjacent
to the 9-pin D-sub connector. On any connected Model 71 pressing and holding this
button for two seconds places this specific unit in its configuration mode; normal
operation of the Model 76D 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 reference level LEDs will display the
Model 71’s current device address. The
rotary level control is used to select the
desired device address; the LEDs will
respond accordingly. Refer to Figures 7
and 8 for details.
To leave the configuration mode and return
a Model 71 to normal operation requires
one last action; again press and hold its
configure button for two seconds. The
selected device address will be stored in
a nonvolatile memory device that is located
inside this specific Model 71.
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Figure 7. Model 71 Control Console Front and
Back Panels
Address
Dim LED
Reference Level LED
A1
OFF
OFF
A2
OFF
ON
A3
ON
OFF
A4
ON
ON
Figure 8. Model 71 Device Address Chart
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.
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for Surround
Upon power up the system will return to
the last operating condition, including all
selected sources, downmix modes, etc. As
a precaution, however, the post-fader surround and stereo monitor output level will
always return to its minimum value. The
rotary level control or the reference level
button must then be used to return the system to the desired monitor output level.
Model 76D Central Controller
The Model 76D’s front panel contains two
LEDs. The control console status LED
will light whenever the Model 76D is communicating under normal operation with
the one or more connected Model 77 or
Model 71 units. A flashing control console
status LED indicates that the DC power
output supporting the control consoles is
in a short-circuit or over-current condition.
The control console status LED will not
light when a Model 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 76D. 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 or
Model 71 Control Consoles that have been
connected. System functions can also be
controlled by means of the metadata and
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,
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downmix, monitor output general functions,
channel mute/solo, display and display
mode, and remote control inputs.
Any change made to any one Model 77
will be reflected in the status LEDs and
displays on all the connected units. Note
that all control console units function
simultaneously—there is no priority of
one unit over the others.
Input Source Selection
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 selection of two inputs 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 (2-channel). The other allows a
stereo signal to be converted to mono. Using the downmix functions simply requires
pressing the desired button. The buttons
are set to always “latch” the functions on
and off. An LED is located adjacent to each
button and lights whenever its respective
function is active. The downmix functions
always impact the post-fader surround and
Model 76D/77 User Guide
Studio Technologies, Inc.
for Surround
stereo monitor outputs. And, depending
on the selected configuration, they may
also impact the pre-fader surround monitor
output. Please refer to the Specifications
section of this guide for a detailed description on how the downmix functions perform
their tasks.
A specific downmix function can only be
enabled when it is applicable for the currently selected input source. This means
that the 5.1 to stereo downmix function
can only be enabled when 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 Surround
When the 5.1 to stereo downmix function
is enabled the LS, RS, and C channels
associated with a surround signal are
combined (“folded down”) with the L and
R signals to create a 2-channel stereo (left
and right) signal. And, depending on the
system’s configuration, the LFE channel
may also be combined with the L and R
signals. The resulting stereo signal, sometimes known as LoRo, is routed to the L
and R surround monitor output channels.
The C, LFE, LS, and RS monitor output channels are muted. By utilizing this
downmix function phase relationships and
inter-channel level issues can be quickly
observed.
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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
monitor output channel while the L, R,
LS, RS, and LFE monitor output channels
are muted.
When a surround source has been selected for monitoring, the 5.1 to stereo
downmix function will automatically enable
whenever the stereo to mono downmix
function is enabled. This ensures that an
operator will hear a mono signal created
by folding down all channels associated
with the selected surround input.
Monitor Output General
Functions
Four buttons and one rotary control are
associated with the post-fader surround
and stereo monitor output functions. The
buttons control operation of the surround
and stereo outputs, reference level, mute
all, and dim functions. The rotary level
control is used to manually set the postfader surround and stereo monitor output
levels. These buttons and the rotary control
do not impact the pre-fader surround and
stereo input C direct monitor outputs.
Surround and Stereo Outputs
The surround/stereo function allows selection between two different loudspeaker
systems. When the surround output is
selected the six post-fader surround monitor output channels are active. The two
channels associated with the post-fader
stereo monitor output are muted. When the
stereo output is selected the left and right
channels associated with the post-fader
stereo monitor output become active; the
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for Surround
six channels of the post-fader surround
monitor output mute.
Remember that the Model 77 Control
Console can be configured to disable
the surround/stereo button. If the button
is pressed and the post-fader stereo monitor output is 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 monitor output
levels to a preset value. Technical personnel, using a sound-pressure-level (SPL)
meter and precision signal source, should
have set this level to meet the requirements of the specific monitoring environment. The LED associated with the
reference level button will light whenever
the function is active. The 4-digit display
will indicate the reference output level.
Note that the system’s default reference
level is full mute so “out of the box” the
Model 77 will display four dashes (– – – –)
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
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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 monitor output level is 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 monitor output level
takes to reach the reference level value, it
will cause the reference level LED to flash!
Mute All
Pressing the mute all button causes the
output channels associated with the postfader surround and stereo monitor output
to mute. The 4-digit display indicates the
mute condition by showing four dashes
(– – – –). The mute all button is always set
to “latch” the function on and off. The LED
associated with the mute all button will
light whenever mute all is active. Note that
if mute all is enabled via the remote mute
all function, the mute all LED will flash.
Dim
The dim function is provided for user convenience, allowing the post-fader surround
and stereo 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
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for Surround
the dim button will enable the function. The
dim button is always set to “latch” the function on and off. The 4-digit display, when
selected for output level mode, will indicate
the revised post-fader monitor output level.
If the requested “dimmed” output level is
equal to or less than –96.0 dB, the monitor
output will go into full mute and the display
will show four dashes (– – – –). When dim
is active the post-fader monitor output level
reduction will apply no matter whether the
level is being set by the rotary level control
or by the reference level button. The LED
associated with the dim button will light
whenever dim is active. If dim mode is enabled via the remote dim function the dim
LED will flash.
It’s worth using a few sentences to discuss
the auto dim off function. Whenever dim
is enabled due to the dim button being
pressed, as well as the rotary level control
being active (reference level mode is not
active), changing the setting of the rotary
level control will automatically turn off
dim. The auto dim off function is a unique
attempt at protecting the aural health of
users. No longer will there be a heart-stopping blast of audio when the dim button
is pressed, supposedly to enable dim, but
actually turning dim off because it was
already enabled. It’s hard to explain unless
you’ve experienced this in person—trust
us, this situation can and does happen!
Note that the auto dim off function is not
active whenever dim is enabled due to
the remote dim function being active. This
allows remote control equipment, such
as a talkback system, to reliably dim the
monitor outputs.
Rotary Level Control
The rotary level control is used to manually
adjust the post-fader surround and stereo
Model 76D/77 User Guide
Studio Technologies, Inc.
monitor output levels. The level control
provides the ability to adjust the post-fader
surround and stereo monitor output level
over a 70 dB range. Technically the rotary
level control is a 24-step-per-revolution
mechanical encoder. The amount of level
change in dB per step (“click”) will depend
on how quickly the control is turned. When
changed slowly, each step represents a
0.5 dB change in level. In this case, to traverse the entire level range would require
rotating the control more than four full
turns. But the Model 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 monitor output channels will automatically mute. As previously discussed,
the 4-digit display indicates the mute condition by showing four dashes (– – – –).
If the mute all function is active the rotary
level control won’t have an impact on the
post-fader surround and stereo 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 monitor outputs, taking place
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for Surround
electrically “after” the input source selection, 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.
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 monitor
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output level 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 Attenuation
If configured for the attenuation mode the
display will show the output level as an
attenuation value in reference to the maximum output. This is in the form of 0.5-dB
steps less than the maximum of 0.0 dB. So
a display of –40.5 would indicate that the
surround or stereo monitor output is set to
be 40.5 dB below the maximum level. As
the rotary level control is moved counterclockwise the output level will go down and
the indicated value will get more negative.
Display in dB SPL
If the Model 77 is configured to display
the 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
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for Surround
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 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
76D and then configured for operation. The
functions are remote mute all and remote
dim. When an external signal activates
remote mute all the LED on the Model 77
associated with the mute all button will
flash. If mute all was already active when
the remote mute all function is activated,
the LED will change from being steadily
lit to flashing.
When an external signal activates remote
dim the LED on the Model 77 associated
with the dim button will flash. If dim was
already active when remote dim is activated, the LED will change from being
steadily lit to flashing.
Model 71 Control Console
The Model 71 Control Console provides
a limited number of pushbutton switches,
LEDs, and a rotary level control for operation status display and control. The
two buttons, along with associated LEDs,
provide access to the dim and reference
level functions. A rotary level control allows
adjustment of the post-fader surround and
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Studio Technologies, Inc.
stereo monitor output level. A status LED
lights steadily whenever normal Model 71
operation is taking place.
Any changes made using the Model 71’s
rotary level control and buttons will be
reflected in the appropriate status LEDs
and displays on 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
monitor output level. Its operating characteristics are identical to those of the Model
77 Control Console, discussed earlier in
this section.
Dim
The dim function allows the post-fader
surround and stereo monitor output level 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 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
The Model 76D relies on an external timing
reference (sync) source for proper operation. This can be in the form of a word
clock, DARS (AES11), AES3id, bi-level
video, or tri-level video reference signal.
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for Surround
In most cases the sync signal will be connected to the sync input BNC connector
located on the Model 76D’s back panel. A
configuration setting also allows the signal
connected to the L/R input of surround input
A to serve as an AES3id timing reference.
Whenever a valid sync signal has been
connected to the Model 76D the sync status
LED, located on the unit’s front panel, will
light. The sample rate of the monitor output
channels will reflect the rate of the sync
input and, if a video sync source is utilized,
the configured rate.
If a valid sync signal is not present several
visual indications are provided. On the Model 76D the sync status LED will flash. On all
connected Model 77 Control Consoles the
4-digit LED display will cease normal operation, instead alternating between the words
no and sync. When a valid sync signal
is again connected the Model 76D’s sync
status LED will light steadily. On the Model
77 units the word sync will momentarily be
displayed followed by a brief display of the
monitor output sample rate. The sample
rate will display as 32.0, 44.1, 48.0, 88.2,
96.0, 176.4, or 192.0, reflecting the impact
of the sync source rate and the Model 76D’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.
Any time a valid sync signal is not connected to the Model 76D the monitor outputs will
automatically revert to an internally generated sample rate of 48 kHz with no digital
audio content present. This audio “black”
signal will allow most connected equipment
to continue to function correctly, of course
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with no meaningful audio signal present. As
soon as a valid sync signal is again connected to the Model 76D the monitor outputs will
automatically switch to their correct sample
rate and audio signals will again be present.
Power Down
Great care was taken in the Model 76D’s
design to minimize the chance that clicks,
pops, or other objectionable audio signals
will be present on the monitor outputs. A
power-down circuit supplies the main microcontroller integrated circuit with an indication
that a power loss is imminent. When this condition is detected the monitor outputs automatically switch to silent audio (audio “black”)
in preparation of a complete loss of signal.
Power-Up Messages and Error
Codes
Upon mains power being applied to the
Model 76D 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 76D software versions:
1. Displays 77
2. Displays Model 77 software version
3. Displays Model 77 unit address
(A1, A2, A3, or A4)
4. Displays 76d
5. Displays Model 76D main software
version
6. Displays FPGA
7. Displays 76D’s logic device software
version
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for Surround
After a successful system power-up sequence normal operation will then commence. Should a problem be encountered
during power up one of two error codes
may show on the Model 77’s 4-digit display.
If Err1 displays it indicates that communication is not taking place with the Model
76D. The most likely cause would be incorrect wiring of the data pair linking the two
units. Err2 indicates that the Model 76D
is having problems with its internal logic
device. (A high-speed field-programmable
gate array (FPGA) serves as the digital
“heart” of the Model 76D and without it no
audio activity can occur.) The only way to
remedy this condition is to first try removing and reconnecting mains power. (And
that’s a long-shot as to whether that would
accomplish anything.) If the error code
continues to be displayed the Model 76D
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
76D’s internal clock. While it would be nice
to proclaim that the engineers at Studio
Technologies came up with a unique and
exotic circuit to perform this function it’s
really not the case. Several semiconductor
companies provide “single-chip” SRC solutions and an excellent one from AKM was
selected for the Model 76D. The technical
capabilities of the Model 76D’s SRC function is stated in this way: the sample rate
of an input signal can range from 1/6 to
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six times the Model 76D’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 76D’s output
sample rate is determined by the external
timing reference (sync) signal and, if required, a configured value. If a word clock,
DARS (AES11), or AES3id signal is the
designated sync source its rate will be the
Model 76D’s output sample rate. If a video
sync signal is connected, the Model 76D’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 76D’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 76D’s SRC function to re-synchronize a signal that proves
most valuable. For example, in typical
post-production and broadcast applications
signals will have a sample rate of 48 kHz.
A Model 76D and all its normally connected input signals will be “locked” to the
main timing reference signal that supports
the 48 kHz sampling rate. But, as an example, a signal associated with a portable
device, while at a 48 kHz sampling rate,
may not be synchronized (“genlocked”)
to the “house” reference. Connecting this
signal to stereo input C will cause the SRC
function to “lock” it to the Model 76D’s rate,
thus allowing it to be monitored over a
loudspeaker system. In addition, the stereo input C direct monitor output can be
connected to other devices that find need
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for the now-synchronized signal. In some
cases it may be useful to connect the
stereo input C direct monitor output to
the input of a signal router, allowing an
entire facility to access the signal.
through their standard power-up sequence
and then normal operation will resume.
Model 76D to Control Console
Connections
The non-audio bits that are part of the
AES3/AES3id monitor output channel data
are actively controlled by the Model 76D’s
software. The Channel Status bits use the
Professional Use of Channel Status block.
They indicate a word length of 24 and the
current sample rate. The correct CRC is
also calculated and inserted. The User bits
are always set to 0. When an external timing reference (sync) source is available to
the system the Validity bits will be set to 1.
Figure 6 gives a detailed description of the
signals that connect the Model 76D Central Controller to the one or more Model 77
or Model 71 Control Consoles. The Model
76D 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 76D’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 76D 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.
Channel Status, User, and
Validity Bits
The Model 76D’s hardware is capable of
routing the C/U/V bit information from surround input A L/R, stereo input C, and the
sync input to the main logic device (FPGA)
and then on to the digital audio transmitter
(DIT) integrated circuits. This is provided
for future use and is not active at this time.
“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
76D Central Controller will mute the monitor output channels as well as saving the
current operating parameters. No clicks,
pops, or other noises will occur when the
Model 77 or Model 71 units are again
connected. The control consoles will go
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Model 76D/77 User Guide
Studio Technologies, Inc.
for Surround
Specifications
Downmix:
Functions: 5.1 to stereo, stereo to mono
Model 76D Central Controller
5.1 to Stereo: LS @ –3 dB summed with L; RS @
–3 dB summed with R; C @ –6 dB summed with
L and R; LFE @ –6 dB summed with L and R (if
enabled); C, LFE, LS, and RS monitor outputs mute
General Audio:
Supported Sample Rates: 32, 44.1, 48, 88.2, 96,
176.4, and 192 kHz
Word Length: 24 bits maximum
Internal Processing: 32 bits
Dynamic Range: 134 dB
Input-to-Output Latency: one sample (e.g., 0.021
milliseconds @ 48 kHz sample rate)
Digital Audio Inputs: five (18 audio channels)
Configuration: two surround (5.1) and three stereo
(2-channel)
Type: AES3id-2001/SMPTE 276M (75 ohms,
unbalanced)
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 Input:
Sources: word clock, DARS (AES11), AES3id,
bi-level video, tri-level video
Jitter: 4 ns pp maximum
Connector: BNC (per IEC 60169-8 Amendment 2)
Termination: 75 ohms, selectable on/off
Digital Monitor Outputs: four (16 audio channels)
Configuration: organized as two surround (5.1)
and two stereo
Type: AES3 (110 ohms/5 Vpp) or AES3id/SMPTE
276M (75 ohms, 1 Vpp), selectable
Stereo to Mono: L @ –3 dB summed with R @
–3 dB to C; L, R, LS, RS, and LFE monitor outputs
mute. (For a surround input this results in the C
output being the sum of L @ –3 dB, R @ –3 dB,
C @ –3 dB, LFE @ –3 dB (if enabled), LS @ –6 dB,
and RS @ –6 dB.)
Control Console Interface:
Type: RS-485, 115.2 kbit/s, 8-1-N
Polling Interval: 50 milliseconds
Power: 12 volts DC, 500 milliamperes maximum
Connector: 9-pin D-subminiature female
Remote Control Inputs: two
Functions: remote mute all, remote dim
Type: +5 V logic, activates on closure to system
common
Connector: 9-pin D-subminiature female
AC Mains:
Requirement: 100 to 230 V, 50/60 Hz, 15 watts
maximum
Connector: 3-blade, IEC 320 C14-compatible
(mates with IEC 320 C13)
Mounting: one space in a standard 19-inch rack
Dimensions:
19.00 inches wide (48.3 cm)
1.72 inches high (4.4 cm)
7.00 inches deep (17.8 cm)
Weight: 6.2 pounds (2.8 kg)
Connector: 25-pin D-subminiature female
Configurable Delay: 0 to 340 milliseconds @
48 kHz sample rate (scaled up or down depending
on actual sample rate)
Model 76D/77 User Guide
Studio Technologies, Inc.
Issue 1, March 2009
Page 41
for Surround
Model 77 Control Console
Application: up to four Model 77 Control Consoles
can be connected to a Model 76D Central Controller
Power: 12 volts DC, maximum current 100 milliamperes, provided by Model 76D Central Controller
Control Data:
Type: RS-485
Data Rate/Format: 115.2 kbit/s, 8-N-1
Connector: 9-pin D-subminiature female
Dimensions (Overall):
7.20 inches wide (18.3 cm)
2.20 inches high (5.6 cm)
5.40 inches deep (13.7 cm)
Weight: 1.7 pounds (0.8 kg)
Model 71 Control Console
Application: up to three Model 71 Control Consoles
can be connected to a Model 76D Central Controller
Power: 12 volts DC, maximum current 35 milliamperes, provided by Model 76D Central Controller
Control Data:
Type: RS-485
Data Rate/Format: 115.2 kbit/s, 8-N-1
Connector: 9-pin D-subminiature female
Dimensions (Overall):
3.20 inches wide (8.1 cm)
2.20 inches high (5.6 cm)
4.10 inches deep (10.4 cm)
Weight: 0.8 pounds (0.4 kg)
Specifications and information contained in this
User Guide subject to change without notice.
Issue 1, March 2009
Page 42
Model 76D/77 User Guide
Studio Technologies, Inc.
for Surround
Appendix A—Connection Pin-Out
Charts
Connections
TASCAM® Signal
Channel High (+)
Signal
Low (–)
Shield
Data + (RS-485)
1
To/From Models 77/71
Signal
Pin
Direction
Pre-Fader L/R
1
24
12
25
Data – (RS-485)
6
To/From Models 77/71
Pre-Fader C/LFE
2
10
23
11
Data Shield
2
To/From Models 77/71
Pre-Fader LS/RS
3
21
9
22
DC + (12 V)
4
To Models 77/71
Stereo Input C Direct
4
7
20
8
DC – (12 V Return)
9
To Models 77/71
Post-Fader L/R
5
18
6
19
DC Power Shield
5
To/From Models 77/71
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 76D is 25-pin
D-subminiature female (DB-25F). Installer must
provide male (DB-25M). Connector uses 4-40
threaded inserts for locking with mating plug.
Note: Connector type on Model 76D is 9-pin D-subminiature
female (DE-9F). Connector uses 4-40 threaded inserts
for locking with mating plug.
Connections between Model 76D and Model 77
and Model 71
3) Wiring scheme follows TASCAM DA-88 convention.
Standard DA-88-type wiring harnesses are directly
compatible, with the exception of 4-40 screw threads
being required.
Connections for Monitor Outputs
Signal
Pin
Direction
Data + (RS-485/RS-422)
7
Not used
Data – (RS-485/RS-422)
2
Not used
Data Shield
1
Shield
Remote Mute All
5
Input
Remote Dim
6
Input
Remote Spare 1
8
Input
Remote Spare 2
9
Input
Remote Input Common
4
Common
Note: Connector type on Model 76D is 9-pin D-subminiature
female. Connector uses 4-40 threaded inserts for
locking with mating plug.
Connector Pin Out for Remote Control Inputs
Model 76D/77 User Guide
Studio Technologies, Inc.
Issue 1, March 2009
Page 43
for Surround
Appendix B—Sync Sources
The Model 76D’s sync input has been tested and confirmed for correct operation with the
following sync signals:
Word Clock: Square wave signal with rate of 32, 44.1, 48, 88.2, 96, 176.4, or 192 kHz.
DARS (AES11) or AES3id: Signal with sample rate of 32, 44.1, 48, 88.2, 96, 176.4, or
192 kHz.
Video: See table below.
Video Format
Video Format
NTSC (“Black Burst”)
1035i/59.98 Hz
PAL (“Black Burst”)
1035i/60 Hz
525i/59.94 Hz
1080i/50 Hz
525p/59.94 Hz
1080i/59.94 Hz
625i/50 Hz
1080i/60 Hz
625p/50 Hz
1080p/23.98 Hz
720p/23.98 Hz
1080p/24 Hz
720p/24 Hz
1080p/25 Hz
720p/25 Hz
1080p/29.97 Hz
720p/29.97 Hz
1080p/30 Hz
720p/30 Hz
1080psf/24 Hz
720p/50 Hz
1080psf/23.98 Hz
720p/59.94 Hz
720p/60 Hz
Issue 1, March 2009
Page 44
Model 76D/77 User Guide
Studio Technologies, Inc.
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