76D/77 User Guide_3 - Studio Technologies

76D/77 User Guide_3 - Studio Technologies
for Surround
Model 76D Central Controller and
Model 77 Control Console
User Guide
Issue 3, September 2010
This User Guide is applicable for systems consisting of:
Model 76D: serial number M76D-00201 and later with software version 3.00 and higher;
Model 77: serial number M77-00151 and later with software version 2.01 and higher
© 2010 by Studio Technologies, Inc., all rights reserved
www.studio-tech.com
50230-0910, Issue 3
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for Surround
Table of Contents
Introduction ................................................................... 5
Installation .................................................................... 8
Configuration ................................................................15
Operation ......................................................................32
Technical Notes ............................................................38
Specifications ...............................................................41
Appendix A—Connection Pin-Out Charts ....................43
Appendix B—Sync Input Sources ................................44
Model 76D/77 User Guide
Studio Technologies, Inc.
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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 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 pre- and post-fader outputs, downmix and mute/solo functions, along with a
multi-format sync input, make the system
powerful yet simple to operate. And by using
the best of contemporary technology, as
well as following rigorous design practices,
the system’s audio quality is excellent.
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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indicators provide complete status information. A 4-digit numeric display indicates
the post-fader monitor output level in real
time. A major strength of the Model 77 is its
ability to configure, under software control,
many important operating parameters. Intended for secondary monitoring locations,
the Model 71 Control Console is a compact
user control surface. It provides three of the
most basic functions: a rotary level control,
dim on/off button, and reference level on/off
button.
While many installations will use only one
Model 77 Control Console, up to three
additional Model 77 or Model 71 Control
Consoles can also be connected. This
provides multiple users with full control over
a facility’s monitor system. And to make
installation simple, the Model 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 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 sources to be
monitored. Up to 340 milliseconds of input
delay can be selected to compensate for
processing delays in an associated video
path. A number of different signals can
serve as the Model 76D’s digital audio timing reference. For synchronization with a
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master timing reference a dedicated source
of word clock, DARS (AES11), bi-level
video, or tri-level video can be connected.
Alternately, the L/R connection of the actively selected surround or stereo input
source can serve as the timing reference.
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.
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 signal level of 5 volts peak-to-peak (Vpp).
For AES3id operation the impedance is
75 ohms and the level is 1 Vpp.
Great care was taken in designing the
system’s architecture, ensuring that the
character of the audio input signals is
preserved. All audio processing is performed in 32 bits using a high-speed
field-programmable gate array (FPGA)
integrated circuit.
The Model 76D occupies one space
(1U) in a standard 19-inch rack. Digital
audio signals are interfaced with the Model
76D’s inputs using nine BNC connectors.
A 10th BNC connector is used by the sync
source. Monitor output signal connections
are made using one 25-pin D-subminiature connector. One 9-pin D-subminiature
connector is used to connect the Model
76D with up to four Model 77 or Model 71
Control Consoles. A second 9-pin “D-sub”
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
Remote control
inputs
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Digital
monitor
output
connections
Sync
Input
connection
Surround Input B
connections
Stereo
Input C
connection
Stereo Input A and
Stereo Input B
connections
Surround Input A
connections
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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
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.
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
post-fader surround and stereo monitor
output channels to automatically mute
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whenever the output level control reaches
maximum attenuation. Using the reference
level function, the post-fader surround and
stereo monitor output levels can be set to
a pre-configured value. This is provided for
audio-with-picture applications that require
a specific monitor output level. The reference level is easily configured by taking an
electronic “snapshot” of the desired monitor output level. For operator confirmation a
4-digit LED readout can display the level of
the post-fader surround and stereo monitor output channels. To match the needs
of a facility, it can be configured to display
either the attenuation level or the sound
pressure level (SPL).
The dim function allows the post-fader
surround and stereo monitor output levels
to be reduced by a fixed dB amount. The
dim level is configured from among four
available values. A mute all function allows the post-fader surround and stereo
monitor output channels to be simultaneously muted. The channel mute/solo
section provides post-fader surround and
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stereo channel monitoring control, allowing
a single channel to be muted or monitored.
Multiple channels can also be simultaneously selected for muting or “soloing.”
A special solo mode is also provided,
called channel pop solo, which offers a
unique aid in monitoring audio material.
Channel pop solo allows the level of a
single channel to be raised while the level
of the other channels is reduced. This helps
to emphasize the content on one channel
without fully muting the others. Broadcast
applications can benefit from the channel
pop solo mode by allowing, for example,
the center channel to be highlighted while
still maintaining some level on the other
channels. The amount of level increase—
the “pop”—as well as the amount of attenuation can be configured to meet the needs
of specific applications or users.
Two functions allow the input sources to be
checked for level or phase inconsistencies.
The 5.1 to stereo downmix function is used
to create a stereo signal from the selected
surround (5.1) source. The stereo to mono
downmix function allows audio on the left
and right channels to be added (summed)
and monitored on the center output channel. The two downmix functions can be
simultaneously enabled, allowing a surround source to be checked for mono compatibility. The downmix functions always
impact the post-fader surround and stereo
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 remote-control
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inputs provide access to the mute all and
dim functions. By providing access to
these functions, talkback or slate activity
from an audio console or other communications system can control the level of the
post-fader surround and stereo monitor
outputs.
Installation
In this section you will be installing the
Model 76D Central Controller in an equipment rack. Connections to the audio inputs
and monitor outputs will be made. A dedicated digital audio timing reference signal
can be connected to the sync input. If
desired, 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 (1U) in a standard 19-inch
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(48.3 cm) equipment rack. Secure the
Model 76D into the equipment rack using two mounting screws per side. Select
a location that is convenient for making
connections to the audio signals as well
as interfacing with the first (or only) Model
77 Control Console. A cable is supplied to
connect the Model 76D to the Model 77. If
the needs of a specific installation dictate,
an alternate-length interconnecting cable
can be fabricated and used.
Audio Connections
Audio connections are made by way of
nine BNC jacks and 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
these jacks and the connector.
Audio Inputs
Two surround (5.1) and three stereo digital
audio sources can be connected. All
sources can be monitored using the preand post-fader surround and post-fader
stereo monitor output channels. A one-toone relationship is maintained between
the input and output channels, i.e., left
input to left monitor output, right input to
right monitor output, center input to center
monitor output, etc. (Of course this won’t
be true in the case where the user has
enabled 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 a sampling rate of up to 192 kHz
and a word length (depth) of up to 24 bits.
It’s best if the connected signal sources
maintain a common sample rate and timing reference. Having all signals “locked”
together helps to ensure proper handling
by the Model 76D’s all-digital signal path.
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There is, however, an exception worth
noting. Circuitry associated with stereo
input C has sample rate conversion (SRC)
capability, allowing virtually any digital
audio signal to be connected. A signal
connected to stereo input C can have an
independent sample rate and timing reference and still be monitored correctly. Refer
to the Technical Notes section of this guide
for a detailed review of the SRC capability.
Nine BNC jacks on the Model 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-attenuating transformer assemblies
typically provide a 3-pin female XLR connector on their input and a female BNC
connector on their output.
Monitor Outputs
The 25-pin D-subminiature connector
labeled Digital Monitor Outputs provides
access to the Model 76D’s 16 channels
of digital audio: pre-fader surround, postfader surround, post-fader stereo, and
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stereo input C direct monitor output. The
pre-fader surround monitor output channels are intended for connection to metering or monitoring equipment that requires
uninterrupted full-level signals. The postfader surround monitor output channels
are intended to connect to the main 5.1
loudspeaker system. The post-fader stereo
monitor output is provided to support a
separate set of stereo monitor loudspeakers. The stereo input C direct monitor
output is essentially a unity gain copy of
the signal connected to stereo input C.
However, the signal does pass through the
sample rate conversion (SRC) and input
delay circuitry. The impact made by these
functions will depend on the specific input
signal and the Model 76D’s configuration
settings.
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.
For flexibility the monitor outputs are
transformer-coupled and can be configured to act as AES3 or AES3id digital
audio sources. The monitor outputs are
configured in two groups with separate
choices available for the pre-fader surround/stereo input C direct group and
post-fader surround/post-fader stereo
monitor output group. When a group is
set for AES3 (110 ohms/5 Vpp) the signals are compatible with AES3 interfaces.
Signals of this type are normally interconnected using shielded twisted-pair cable
and 3-pin XLR connectors. When a group
is configured for AES3id (75 ohms/1 Vpp)
the source impedance and signal level
are compatible with the requirements of
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AES3id interfacing. These signals are typically interconnected using coaxial cable
terminated with 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; one pin remains unused. Each set of
three pins provides an independent interface. In the analog world this would allow
eight audio signals to be transported. But
with AES3/AES3id digital audio signals
this allows support for 16 audio channels;
eight interfaces each supplying two audio
channels.
A wiring assembly prepared for the Model
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 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.
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For compatibility with AES3id unbalanced
digital audio signals connect the D-sub’s
+ terminal as signal high, and both the –
and shield terminals as the signal low/shield.
When terminating to a BNC plug the D-sub’s
+ terminal should connect to the center pin;
the – and the shield connections should go
to the “body” of the BNC plug. To clarify, for
optimal operation it is best to connect both
the – and shield connectors together directly
on the D-sub plug, rather than at the BNC
end of the interface assembly. Note that the
output circuitry is transformer-coupled so it
is possible to just connect to the + and –
terminals and still experience correct operation. This would leave the shield connection
unterminated.
Refer to Figure 4 or Appendix A for the
exact connection details. Note that unlike
a DA-88-style assembly, the two threaded
fasteners associated with the Model 76D’s
D-sub connector use 4-40 threads. This
complies with the original design standard
for D-subminiature connectors.
Connections
TASCAM® Signal
Channel High (+)
Pre-Fader L/R
Signal
Low (–)
Shield
1
24
12
25
Pre-Fader C/LFE
2
10
23
11
Pre-Fader LS/RS
3
21
9
22
Stereo Input C Direct
4
7
20
8
Post-Fader L/R
5
18
6
19
Post-Fader C/LFE
6
4
17
5
Post-Fader LS/RS
7
15
3
16
Post-Fader Stereo
8
1
14
2
Notes: 1) All signals transformer-coupled digital audio;
selectable for AES3 or AES3id compatibility.
2) Connector type on Model 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 possible exception of 4-40 screw
threads being required.
Figure 4. Connections for Monitor Outputs
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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.
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.
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.
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.
Sync Input
The Model 76D requires a timing reference
(sync) signal so that the digital audio input
and output signals will function correctly.
A configuration setting allows the source
of sync to be the L/R input of the currently
selected surround or stereo digital audio
input. While this is acceptable, audio
artifacts (clicks or noise) can occur when
switching between inputs. A better method
is to connect a dedicated timing reference
signal to the Model 76D’s sync input connector. The connected sync signal must
maintain a stable relationship between
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itself and the digital audio inputs. The
actual sync source can be in one of several formats: word clock, DARS (AES11),
bi-level video, or tri-level video.
An overview of the various compatible
timing reference signals might prove
worthwhile. Word clock is a digital signal
that is locked in phase and frequency to
the sample rate of the associated digital
audio sources. DARS (digital audio reference source) is a timing signal compliant
with the AES11 standard. It’s sometimes
referred to as “AES3-black.” Technically it
is similar to an AES3 or AES3id signal but
is generated specifically as a timing reference signal. Bi-level video sync signals
were originally provided to support NTSC
and PAL broadcast applications, although
they continue to be used by contemporary
equipment. Tri-level sync signals were
primarily associated with facilities that
supported high-definition (HD) video
equipment, however the importance of this
type of sync seems to be waning. Both
bi-level and tri-level signals can be found
at numerous rate combinations, configured
to allow for compatibility with the various
video formats.
With the wide range of allowable sync
sources proper Model 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 is connected to the sync input BNC connector
located on the Model 76D’s back panel.
For flexibility this input can be configured
to be high-impedance (“floating”) or terminated with an impedance of 75 ohms.
A sync source that is dedicated for use by
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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.
Remote Control Inputs
Support is provided for two remote control input functions: remote mute all and
remote dim. The Model 76D’s inputs use
logic gates, “pulled up” to +5 volts DC by
way of resistors, which are active whenever they are brought to their logic low state.
Inputs of this type are commonly referred
to as GPI inputs. While the input circuitry
is protected from over-current and static
discharge (ESD), care should be taken to
prevent nasty signals from reaching them.
The inputs are active only when held in
the low state; they can’t be configured to
change state (“latch”) in response to a
logic pulse.
A 9-pin 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 to 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
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.
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Signal
Pin
Direction
Data + (RS-485/RS-422)
7
Not used
Data – (RS-485/RS-422)
2
Not used
Data Shield
1
Shield
Remote Mute All
5
Input
Remote Dim
6
Input
Remote Spare 1
8
Input
Remote Spare 2
9
Input
Remote Common
4
Common
Note: Connector type on Model 76D is 9-pin D-subminiature
female (DE-9F). Connector uses 4-40 threaded inserts
for locking with mating plug.
Figure 5. Connector Pin Out for Remote Control
Inputs
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.
Refer to Figure 6 or Appendix A for details
A 9-pin female D-sub connector, labeled
To/From Central Controller, is provided on
the back panel of each Model 77 Control
Console. A cable with 9-pin male D-sub
(DE-9M) 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
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2-pair audio cable. This cable, consisting
of two twisted pairs each with an individual
shield, is typically sleek, flexible, and available in many colors. One pair and shield
can be used for the data connections while
the other pair and shield can be used for
the DC connections. This implementation
has the advantages of providing a shield
for the data path and a more robust common connection (two conductors including
the shield) for the DC power circuit.
A few simple calculations are required to
determine the maximum cable length when
connecting a Model 76D to a Model 77.
The differential transmission scheme used
by the system’s RS-485 interface makes
an interconnection in excess of 1000 feet
(>300 meters) easily possible. The limiting
factor is typically the ability of the wiring
to pass the DC power supplied by the
Model 76D to a 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, 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
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
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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 required current in amperes).
Remember to include the resistance in
both the DC + and DC – wires when calculating the voltage drop. If it’s greater than
3 volts your cable is too long or the wire
gauge is too small.
Additional Control Consoles
Some installations may benefit from the
Model 76D’s ability to be controlled by
additional control consoles. At least one
Model 77 Control Console must be connected to the 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
Issue 3, September 2010
Page 14
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 required current for a
Model 77 is 100 milliamperes while a Model 71 requires only 35 milliamperes. It’s
important to review this information prior to
creating the interconnection scheme to be
used for installing multiple Model 77 units.
AC Mains Power
The Model 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 5-15L) on one end and an
IEC 320 C13 socket on the other. Units
bound for other destinations require that
the appropriate cord be used. The wire colors in the mains cord must conform to the
internationally recognized color code and
should be terminated accordingly:
Connection
Neutral (N)
Line (L)
Protective Earth (E)
Wire Color
Light Blue
Brown
Green/Yellow
Safety Warning: The Model 76D does
not contain an AC mains disconnect
switch; the AC mains cord plug serves
as the disconnection device. Safety
considerations require that the plug and
associated outlet be easily accessible
to allow rapid disconnection of AC
mains power should it prove necessary.
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for Surround
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 operation
can commence and the two LEDs will perform their intended functions. Once operating data is being interchanged with the
one or more connected Model 77 or Model
71 Control Consoles the control console
status LED will light. The sync status LED
will light if a valid sync source has been
recognized. The sync status LED will flash
if a valid sync source is not recognized.
Also upon application of mains power, all
connected Model 77 units will go through
a power-up sequence, lighting each of
its LEDs in succession. Using its 4-digit
display, each Model 77 will then momentarily display its address, its software
version, and the main and logic device
software versions of the associated Model
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 Model 71’s three LEDs will light
momentarily. After these LEDs have been
lit, the device address will be shown briefly
using the dim and reference level LEDs, as
shown in Figure 8 in the Operation section.
When this is complete the Model 71 will
begin normal operation and its status LED
will light if communication is established
with the Model 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.
Model 76D/77 User Guide
Studio Technologies, Inc.
Should an error be detected during the
start-up process the two LEDs on the Model 76D’s front panel will continue to flash in
cadence indefinitely. On the Model 77 units
a diagnostic code may be displayed. Refer
to the Technical Notes section of this user
guide for details.
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. However,
one configuration choice is available for
each of the connected Model 71 Control
Consoles.
Configurable Parameters
Many StudioComm functions can be
configured to meet the exact needs of an
installation. A Model 77 Control Console
is used to display and select the desired
system configuration. Here’s an overview
of what can be configured:
• Model 77 Device Address (unique for
each unit)
• Stereo Input C Sample Rate Converter
• Post-Fader Stereo Output
• Sync Source
• Sync Input Termination
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for Surround
• 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
• 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 its 9-pin D-sub connector. On any connected Model 77 pressing and holding this
button for two seconds places both this
specific unit and the Model 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.
Issue 3, September 2010
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As a user aid, a Model 77 that has entered
the configuration mode will have its mute
and solo LEDs (associated with the channel mute/solo section) light in an alternating
manner. Other connected Model 77 units
will indicate that they have entered the
standby mode by simultaneously flashing
their mute and solo LEDs.
To leave the configuration mode and return
the system to normal operation requires
one last action to be made on the Model 77
unit that’s in its configuration mode; press
and hold its configure the button for two
seconds. Note that configuration changes
are stored in nonvolatile memory only after
the configuration mode has been exited.
Our apologies to those of you who find
the configure button a pain to use, but it’s
supposed to be that way! Seriously, the top
of the button is slightly recessed from the
back panel, making it harder to accidentally
activate. We didn’t want normal operation to
cease because someone pushed a Model
77 into a “rats nest” of schedules, memos
from management, and empty coffee cups!
But a firm press with the fleshy part of an
index finger should do the trick.
There is no problem frequently “tweaking” the system’s operating parameters
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. However,
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 76D/77 User Guide
Studio Technologies, Inc.
for Surround
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, third, or fourth Model 77 each unit
must be configured with a unique device
address. Problems will occur if more than
one unit has the same address! It’s important to highlight the fact that the device
address is the only setting that must be
done on each individual Model 77 unit. All
other settings can be made on any one
of the connected Model 77 units. Be sure
that any selected address does not conflict
with addresses to be assigned to Model 71
units.
Stereo Input C Sample Rate
Converter
Circuitry associated with stereo input C
can provide sample rate conversion (SRC)
for digital audio signals connected to
that input. The acceptable input range for
sample rate conversion is very wide, but
is dependent upon the output sample rate.
With an output sample rate of 48 kHz any
signal with a sample rate over a range of
8 to 216 kHz can be properly monitored
by the system. This capability can be
especially useful with signals that are not
synchronized with respect with the others
connected to the Model 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
Model 76D/77 User Guide
Studio Technologies, Inc.
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
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
post-fader stereo monitor output.
Sync Source
The Model 76D requires that the designated external timing reference (sync) be
defined. Three of the choices—word clock,
DARS, and video—are associated with a
signal that is connected to the sync input
BNC connector. The fourth choice allows
the L/R input of the currently selected surround or stereo digital audio input to serve
as the system’s sync source.
Sync Input Termination
The sync input circuitry can be configured
to terminate the signal connected to the
back-panel sync input BNC connector.
When termination is selected a 75 ohm
load is applied to the signal. When the
sync input is not terminated the input impedance is very high, essentially applying
no load to the source. If the sync source
is connected only to the Model 76D then
enabling termination is typically appropriate. However, if the sync source is being
“shared” by multiple inputs then care must
be taken so that the signal is only terminated by one device.
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for Surround
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.
Pre-Fader Surround/Stereo
Input C Direct Monitor Output
Type
To meet the needs of specific installations
the nominal impedance and level characteristic of the pre-fader surround and
stereo input C direct monitor outputs can
be selected. They are selected as a group;
configuration of individual outputs is not
provided. If the output signals are going
to be connected to balanced AES3 inputs
then the setting that provides a source
impedance of 110 ohms and a nominal
5 Vpp output level would be appropriate.
If the output signals are going to be connected to unbalanced AES3id inputs then
the setting that provides a 75 ohm source
impedance and a nominal output level
of 1 Vpp would be correct.
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 configuring the pre-fader surround/
stereo input C direct digital monitor output
type also applies to these outputs.
Issue 3, September 2010
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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:
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.
Model 76D/77 User Guide
Studio Technologies, Inc.
for Surround
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.
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
Model 76D/77 User Guide
Studio Technologies, Inc.
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
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
Issue 3, September 2010
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for Surround
be appropriate, reflecting the widely used
audio-for-picture 85 dB monitoring reference
level. (Typically this 85 dB is really 85 dBC,
indicating that a C-weighting filter has
been applied to the measurement.) Other
common reference SPL values, such as
82 dB and 87 dB, are well within the allowable range.
Auto Reference Level Off
When auto reference level off is enabled,
the function automatically turns the reference level function off if a change is made
to the rotary level control while the reference level function is active.
Dim Level
The dim function is used to reduce the 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.
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.
Issue 3, September 2010
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The selected time delay applies to all input
signals and cannot be applied selectively.
The configured delay time is referenced
to a sample rate of 48 kHz. In the case of
input signals with a sample rate of 48 kHz
the delay range is 0 to 340 milliseconds in
1-millisecond steps. For other sample rates
the time must be linearly scaled. For example, for a sample rate of 96 kHz the actual
time range is 0 to 170 milliseconds. In this
case selecting a delay of 120 on the Model
77 will result in an actual time delay of 60
milliseconds. For 192 kHz sampling the
time range is 0 to 85 milliseconds. Selecting a delay of 240 will result in a time delay
of 60 milliseconds.
LFE Downmix Mode
By default, when the 5.1 to stereo downmix function is active the LFE channel
associated with a surround input is muted.
This removes LFE content from the “downmixed” signal. In most applications this is
appropriate. However, for special situations
a configuration mode allows the LFE channel to be part of the downmix signal flow.
When the LFE downmix mode is enabled,
if surround input A or B is the currently
selected input and the 5.1 to stereo downmix function is active, the LFE signal level
is reduced in level by 6 dB and added to
both the left and right output channels. As
expected, even when the LFE downmix
mode is active the LFE output channel
will still mute when 5.1 to stereo downmix
is active.
Pre-Fader Surround Monitor
Output Mode
The pre-fader surround monitor output can
be configured as to its place in the Model
76D’s signal flow. The choices are pre- or
post-downmix. In the pre-downmix mode
Model 76D/77 User Guide
Studio Technologies, Inc.
for Surround
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.
resetting the reference level would require
getting out an SPL meter and a calibrated
signal source. This is a hassle you may not
need!
Model 71 Control Console
Configuration
The only configuration choice available on
a Model 71 is its device address. It must be
selected so as not to conflict with the device address of any other connected Model
71 or Model 77 Control Console. The
choices are A1, A2, A3, and A4. All Model
71 units have a default device address of
A4; Model 77’s units have a default device
address of A1. This ensures that, in most
cases, no change will have to be made.
Refer to Figures 7 and 8 for details.
Channel Pop Solo Mode
Offset Levels
Two parameters can be configured that determine how the channel pop solo function
impacts audio levels. The up offset level
sets the amount of increase (gain) that a
channel will experience when it is soloed
in the channel pop solo mode. The down
offset level sets the amount of decrease
(attenuation) that the non-soloed channels
will experience when a channel is active in
the channel pop solo mode.
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
Model 76D/77 User Guide
Studio Technologies, Inc.
Figure 7. Model 71 Control Console Front and
Back Panels
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for Surround
A small button is located on the back of
each Model 71 Control Console, adjacent
to the 9-pin D-sub connector. Pressing and
holding this button for two seconds places
this specific unit in its configuration mode;
normal operation of the Model 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.
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
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.
Issue 3, September 2010
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Model 76D/77 User Guide
Studio Technologies, Inc.
for Surround
Configuration—Entering and Exiting Configuration Mode
and hold the configuration
 Press
button for 2 seconds to enter or
exit the configuration mode.
These LEDs will light alternately
when configuration mode is active.
Model 76D/77 User Guide
Studio Technologies, Inc.
Issue 3, September 2010
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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.
Issue 3, September 2010
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Model 76D/77 User Guide
Studio Technologies, Inc.
for Surround
Configuration—Sync Source, Sync Input Termination,
Audio-Synced-to-Video Sample Rate, and Monitor Output Types
This LED displays the configuration
of the sync input termination. LED
not lit means sync input is not terminated; LED lit means terminated with
75 ohms. Use the button to change
the configuration.
Use the Channel Solo C and LFE buttons to select the pre-fader surround/
stereo input C direct monitor output
type. Use the buttons to change the
configuration. C LED lit means AES3id
(75 ohms/1 Vpp); LFE LED lit means
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
source, sync input termination,
audio-syncedto-video-sample
rate, and monitor output types.
Use these buttons
to select the sync
source.
LED Surround B
lit means sync
input, video;
LED Stereo A lit
means sync input,
DARS;
LED Stereo B lit
means sync input,
word clock;
LED Stereo C
lit means L/R of
currently selected
input.
Use the level control to adjust the audiosynced-to-video sample rate. Available
sample rates are 32, 44.1, 48, 88.2, 96,
176.4, and 192 kHz.
Default:
Sync source is L/R of currently selected input.
Sync input terminated.
Audio-synced-to-video sample rate 48 kHz.
Pre-fader surround/stereo input C direct monitor output type AES3 (110 ohms/5 Vpp).
Post-fader surround/stereo monitor output type AES3 (110 ohms/5 Vpp).
Model 76D/77 User Guide
Studio Technologies, Inc.
Issue 3, September 2010
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for Surround
Configuration—Reference Level
and hold the Reference Level button for 5 seconds to take a “snapshot”
 Press
of the level control’s setting at the time configuration mode was entered. The
Reference Level LED will flash when the button is initially pressed and then
light steadily when the “snapshot” has been taken.
Default:
Reference level set for –60.0 dB post-fader monitor output level.
Note:
The 5-second button-press delay is a safety feature ensuring that the reference level will not be accidently
changed. To permanently store the new value, you must still exit the configuration mode.
Issue 3, September 2010
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Model 76D/77 User Guide
Studio Technologies, Inc.
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.
Model 76D/77 User Guide
Studio Technologies, Inc.
Issue 3, September 2010
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for Surround
Configuration—Dim Level, Remote Mute All, Remote Dim,
and Input Delay
This LED displays the configuration of
remote mute all. LED not lit means
remote mute all is disabled; LED lit
means enabled. Use the button to
change the configuration.
This LED displays the configuration
of remote dim. LED not lit means
remote dim is disabled; LED lit
means enabled. Use the button to
change the configuration.
Use these buttons
to select dim level.
LED Surround B lit
means –10 dB;
LED Stereo A lit
means –15 dB;
LED Stereo B lit
means –20 dB;
LED Stereo C lit
means –25 dB.
and hold the Dim button to
 Press
display and select the dim level,
remote mute all, remote dim, and
input delay.
Default:
Use the level control to adjust the input delay.
Range is from 0 to 340. The display shows
delay in milliseconds at 48 kHz sampling
rate. The value is scaled up or down for other
sample rates.
–20 dB dim level.
Remote mute all enabled.
Remote dim enabled.
Input delay 0 ms.
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Model 76D/77 User Guide
Studio Technologies, Inc.
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.
Model 76D/77 User Guide
Studio Technologies, Inc.
Issue 3, September 2010
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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.
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Model 76D/77 User Guide
Studio Technologies, Inc.
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 source is L/R of currently selected input.
Sync input terminated.
Audio-synced-to-video sample rate 48 kHz.
Pre-fader surround/stereo input C direct monitor output
type AES3 (110 ohms/5 Vpp).
Post-fader surround/stereo monitor output type
AES3 (110 ohms/5 Vpp).
Reference level set for –60.0 dB post-fader monitor
output level.
Attenuation display mode selected.
85.0 dB SPL reference level.
Auto reference level off disabled.
–20 dB dim level.
Remote mute all enabled.
Remote dim enabled.
Input delay 0 ms.
LFE downmix disabled.
Pre-fader surround 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.
Model 76D/77 User Guide
Studio Technologies, Inc.
Issue 3, September 2010
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for Surround
Operation
Now that you’ve installed and configured
the system, you’re ready to go. You should
find operation very easy. However, taking
time to study this section of the guide may
prove valuable.
also be controlled by means of the remote
control inputs.
Model 77 Control Console
To make things easy to describe, the Model 77’s operator functions are divided into
six main groups: input source selection,
downmix, monitor output general functions,
channel mute/solo, display and display
mode, and remote control inputs.
Upon power up the system will return to
the last operating condition, including the
selected source, downmix modes, etc. As
a precaution, however, the post-fader surround and stereo monitor output level will
always return to their minimum value. The
rotary level control or the reference level
button must then be used to return the
system to the desired monitor output level.
Any change made to any one Model 77
unit will be reflected in the LEDs and
displays on all the connected units. Note
that all control consoles function simultaneously—there is no priority of one unit
over the others.
Model 76D Central Controller
Input Source Selection
The Model 76D’s front panel contains two
LEDs. The control console status LED will
light whenever the Model 76D is communicating with the one or more connected
Model 77 or Model 71 units. A flashing
control console status LED will indicate
that the DC power output supporting the
control consoles is in a short-circuit or
over-current condition. The control console
status LED will not light when a Model 77
is in the configuration mode or when the
Model 77 is going through its power-up
sequence.
The sync status LED will light whenever
a valid timing reference signal is being
received by the Model 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. Two system functions can
Issue 3, September 2010
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To select an input source press one of the
five input source buttons. The corresponding LED will light to indicate that the input
has been selected. Typically, only one
source will be selected for monitoring at
any one time. However, input stereo C can
be selected by itself, or mixed (summed)
with one of the other four inputs. To accomplish this is easy: simply press and hold
input stereo C then press the button associated with the other desired input source.
The two corresponding LEDs will light.
Alternately, press and hold the first desired
input (other than input stereo C) and then
press the input stereo C button.
Downmix
Two downmix functions allow users to perform “real-world” audio format compatibility
checks. One function allows a surround
(5.1) signal to be “folded down” (mixed)
to stereo. The other allows a stereo signal
to be converted to mono. Using the downmix functions simply requires pressing
Model 76D/77 User Guide
Studio Technologies, Inc.
for Surround
the desired button. The buttons are set to
always “latch” the functions on and off. An
LED is located adjacent to each button
and lights whenever its respective function
is active. The downmix functions always
impact the post-fader surround and stereo
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 if you’d like a detailed description of how the downmix functions perform
their tasks.
A specific downmix function can only be
enabled when it is applicable for the currently selected input source. This means
that the 5.1 to stereo downmix function
can only be enabled when surround input
A or B is selected.
The Model 77 associates the state of the
downmix functions with the currently selected input. For example, if surround input
A is the selected input source and the 5.1
to stereo downmix function is enabled,
this condition will be “remembered” when
switching to one of the stereo input sources. Upon returning to surround input A, the
5.1 to stereo downmix function will again
become active.
5.1 to Stereo
When the 5.1 to stereo downmix function
is enabled the LS, RS, and C channels
associated with a surround source are
combined (“folded down”) with the L and
R signals to create a 2-channel stereo (left
and right) signal. And, depending on the
system’s configuration, the LFE channel
may also be combined with the L and R
signals. The resulting stereo signal, sometimes known as LoRo, is routed to the L
and R surround monitor output channels.
The C, LFE, LS, and RS monitor output
Model 76D/77 User Guide
Studio Technologies, Inc.
channels are muted. By utilizing this
downmix function phase relationships and
inter-channel level issues can be quickly
observed.
Stereo to Mono
The stereo to mono downmix function
combines the L and R audio channels to
create a single-channel monaural signal.
This signal is sent out the C surround
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
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for Surround
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 postfader stereo monitor output become active;
the 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 –60.0 dB so “out of the box” the
Model 77 will display –60.0 when reference
level mode is enabled.
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How the rotary level control functions
whenever the reference level mode is
active depends on a configuration setting.
If the auto reference level off function is
disabled turning the rotary level control will
have no impact on the reference level function; it will remain active. If the auto reference level off function has been enabled
turning the rotary level control will cause
the reference level function to automatically turn off.
The LED associated with the reference
level button can also serve as a calibration
aid. If the reference level mode is not active, whenever the post-fader surround
or stereo 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.
Model 76D/77 User Guide
Studio Technologies, Inc.
for Surround
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
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, and the rotary level control is
active (reference level mode is not active),
changing the setting of the rotary level
control will automatically turn off dim. The
auto dim off function is a unique attempt
at protecting the aural health of users. No
longer will there be a heart-stopping blast
of audio when the dim button is pressed,
supposedly to enable dim, but actually
turning dim off because it was already
enabled. It’s hard to explain unless you’ve
experienced this in person—trust us, this
situation can and does happen!
Model 76D/77 User Guide
Studio Technologies, Inc.
Note that the auto dim off function is not
active whenever dim is enabled due to
the remote dim function being active. This
allows remote control equipment, such
as a talkback system, to reliably dim the
monitor outputs.
Rotary Level Control
The rotary level control is used to manually
adjust the post-fader surround and stereo
monitor output levels. The level control
provides the ability to adjust the post-fader
surround and stereo 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 five full
turns. But the Model 77’s software detects
when the control is rotated more quickly
and increases the amount of level change
in dB per step. A little experimentation will
allow the user to acquire a good “feel” for
how best to use the control.
The reference level LED will flash when
the rotary level control sets the output
level to be the same as the stored reference level. Whenever the rotary level control attempts to set the output level for less
than –70.0 dB, the post-fader surround
and stereo 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
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for Surround
output levels. It’s also not active whenever
the reference level function is active, except if the auto reference level off function
has been enabled.
Channel Mute/Solo
The channel mute/solo functions allow
specific channels to be selected for individual or group mute or “solo” monitoring.
The functions impact the post-fader surround and stereo monitor outputs, taking
place electrically “after” the input source
selection delay, downmix, and level control
functions.
The mute/solo mode button and the six
channel mute/solo buttons, along with associated LEDs, work together to provide
excellent operating flexibility. The channel
mute/solo mode button allows the operator
to select between the mute and solo functions. It is also used to select which solo
mode, normal or channel pop, is active.
Going from mute mode to solo mode, or
vice-versa, clears all active mutes or solos.
Pressing the mode button twice is a legitimate means of quickly clearing muted or
soloed channels. To mute or solo a channel simply requires pressing one of the
channel mute/solo buttons. The buttons
function in a press-to-enable/press-todisable “latching” mode. Multiple channels
can be muted or soloed at the same time.
The LED associated with any muted or
soloed channels is used to indicate that
the function is active.
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
Issue 3, September 2010
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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
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 of Attenuation
If configured for the attenuation mode the
display will show the output level as an
attenuation value in reference to the maximum output. This is in the form of 0.5-dB
steps less than the maximum of 0.0 dB. So
a display of –40.5 would indicate that the
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.
Model 76D/77 User Guide
Studio Technologies, Inc.
for Surround
(Typically, the level value would actually
be in dBC, the C-weighted sound pressure
level.) When the reference level button is
enabled, or the rotary level control is set so
that the reference level has been reached,
the display will typically show something
in the range of 82 to 87 dB. Assuming that
the monitoring environment has been correctly calibrated, this would indicate that
an average listening level of 85 dB, for
example, had been achieved.
Channel Pop Solo Display
As has been previously discussed, the
channel pop solo mode offers a unique
way of sonically highlighting an individual
channel. A channel selected for soloing
in this mode will have its level increased
while the other non-soloed channels will
be reduced in level. To highlight this condition the letters POP will appear in the
4-digit display whenever a channel is
actively being soloed in the channel pop
solo mode. This ensures that a user will
understand that the 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.
Model 76D/77 User Guide
Studio Technologies, Inc.
When an external signal activates remote
dim the LED on the Model 77 associated
with the dim button will flash. If dim was
already active when remote dim is activated, the LED will change from being
steadily lit to flashing.
Model 71 Control Console
The Model 71 Control Console provides
a limited number of pushbutton switches,
LEDs, and a rotary level control for status
display and control. The two buttons, along
with associated LEDs, provide access to
the dim and reference level functions. A
rotary level control allows adjustment of
the post-fader surround and stereo monitor
output level. A status LED lights steadily
whenever normal Model 71 operation is
taking place.
Any changes made using the Model 71’s
rotary level control and buttons will be
reflected in the appropriate LEDs and
displays on all the connected Model 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.
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for Surround
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 an AES3id,
word clock, DARS (AES11), bi-level video,
or tri-level video reference signal. In most
cases the sync signal will be connected to
the sync input BNC connector located on
the Model 76D’s back panel. Alternately, a
configuration choice allows the L/R input
of the AES3id source currently selected for
monitoring to also serve as the system’s
timing reference. Whenever a valid sync
signal has been connected to the Model
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
Issue 3, September 2010
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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 that 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 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 silence
(audio “black”) in preparation for a complete loss of signal.
Power-Up Messages and
Error Codes
Upon mains power being applied to the
Model 76D all connected Model 77 units
will go through a power-up sequence.
Model 76D/77 User Guide
Studio Technologies, Inc.
for Surround
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 (FPGA)
software version
After a successful system power-up
sequence normal operation will then commence. Should a problem be encountered
during power up one of two error codes
may show on the Model 77’s 4-digit 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 it 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.
Model 76D/77 User Guide
Studio Technologies, Inc.
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 timing. While it would be
nice to proclaim that the engineers at
Studio Technologies came up with a
unique and exotic circuit to perform this
function it’s really not the case. Several
semiconductor companies provide “singlechip” SRC solutions and an excellent one
from AKM was selected for the Model 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 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 selected timing reference
(sync) signal and, if required, a configured
value. If a word clock, DARS (AES11),
or AES3id signal is the designated sync
source its rate will be the Model 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.
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for Surround
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 postproduction and broadcast applications all
signals will have a sample rate of 48 kHz.
A Model 76D and all of its normally connected input signals will be “locked” to the main
timing reference signal that supports the
48 kHz sampling rate. But, as an example,
a signal associated with a portable device,
while at a 48 kHz sampling rate, may not be
synchronized (“genlocked”) to the “house”
reference. Connecting this signal to stereo
input C will cause the SRC function to “lock”
it to the Model 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 for the now-synchronized signal. In some cases it may be useful to connect the stereo input C direct monitor output
to the input of a signal router, allowing an
entire facility to access the signal.
Model 76D to Control Console
Connections
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
Issue 3, September 2010
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second, receiving button and rotary level
control information and sending LED and
4-digit display status data.
“Hot” Disconnection of
Control Consoles
There’s no problem relocating one or more
Model 77 or Model 71 Control Consoles
while the StudioComm system is operating. You can disconnect the 9-pin interconnecting cable, move the unit (or units), and
then reconnect without issue. Upon disconnection of all control consoles the Model
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
through their standard power-up sequence
and then normal operation will resume.
Channel Status, User, and
Validity Bits
The non-audio bits that are part of the
AES3/AES3id monitor output channel data
are actively controlled by the Model 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 a valid timing
reference (sync) source is recognized by
the system the Validity bits will be set to 1.
The Model 76D’s hardware is capable of
routing the C/U/V bit information from any
of the L/R inputs, as well as the sync input,
to the main logic device (FPGA) and then
on to the digital audio transmitter (DIT) integrated circuits. This is provided for future
use and is not active at this time.
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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
Input-to-Output Latency: one sample (e.g., 0.021
milliseconds @ 48 kHz sample rate)
Stereo to Mono: L @ –3 dB summed with R @
–3 dB to C;
L, R, LS, RS, and LFE monitor outputs mute (for a
surround input this results in the C output being the
sum of L @ –3 dB, R @ –3 dB, C @ –3 dB, LFE @
–3 dB (if enabled), LS @ –6 dB, and RS @ –6 dB)
Digital Audio Inputs: five (18 audio channels)
Configuration: two surround (5.1) and three stereo
Control Console Interface:
Type: RS-485, 115.2 kbit/s, 8-1-N
Type: AES3id-2001/SMPTE 276M (75 ohms,
unbalanced 1 Vpp)
Polling Interval: 50 milliseconds
Connectors: BNC (per IEC 60169-8 Amendment 2)
Connector: 9-pin D-subminiature female (DE-9F)
Sample Rate Conversion (SRC):
Application: available on Stereo Input C
Remote Control Inputs: two
Functions: remote mute all, remote dim
Input Sample Rate Range: 8 to 216 kHz, limited
to 1/6 to 6 times the output sample rate
Type: +5 V logic, activates on closure to system
common
Latency: 1 millisecond, nominal
Connector: 9-pin D-subminiature female (DE-9F)
Sync Source: configured to follow L/R of currently
selected input or signal connected to sync input
AC Mains:
Requirement: 100 to 230 V, 50/60 Hz, 15 watts
maximum
Word Length: 24 bits maximum
Internal Processing: 32 bits
Dynamic Range: 135 dB
Sync Input:
Compatible Sources: word clock, DARS (AES11),
bi-level video, tri-level video
Jitter: 4 ns pp maximum
Connector: BNC (per IEC 60169-8 Amendment 2)
Termination: 75 ohms, selectable on/off
Digital Monitor Outputs: four (16 audio channels)
Configuration: organized as two surround (5.1)
and two stereo
Type: AES3 (110 ohms/5 Vpp) or AES3id/SMPTE
276M (75 ohms 1 Vpp), selectable
Power: 12 volts DC, 500 milliamperes maximum
Connector: 3-blade, IEC 320 C14-compatible
(mates with IEC 320 C13)
Dimensions:
19.00 inches wide (48.3 cm)
1.72 inches high (4.4 cm)
7.00 inches deep (17.8 cm)
Mounting: one space (1U) in a standard 19-inch
rack
Weight: 6.2 pounds (2.8 kg)
Connector: 25-pin D-subminiature female (DB-25F)
Configurable Delay: 0 to 340 milliseconds @
48 kHz sample rate (scales up or down depending
on actual sample rate)
Model 76D/77 User Guide
Studio Technologies, Inc.
Issue 3, September 2010
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 nominal (9 volts DC minimum),
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 (DE-9F)
Dimensions (Overall):
7.20 inches wide (18.3 cm)
2.20 inches high (5.6 cm)
5.40 inches deep (13.7 cm)
Weight: 1.7 pounds (0.8 kg)
Model 71 Control Console
Application: up to three Model 71 Control Consoles
can be connected to a Model 76D Central Controller
Power: 12 volts DC nominal (9 volts DC minimum),
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 (DE-9F)
Dimensions (Overall):
3.20 inches wide (8.1 cm)
2.20 inches high (5.6 cm)
4.10 inches deep (10.4 cm)
Weight: 0.8 pounds (0.4 kg)
Specifications and information contained in this
User Guide subject to change without notice.
Issue 3, September 2010
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 possible 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 (DE-9F). 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 3, September 2010
Page 43
for Surround
Appendix B—Sync Input 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.
Bi-Level and Tri-Level Video: See table below.
Video Format
Video Format, continued
NTSC (“Black Burst”)
1035i/59.98 Hz
PAL (“Black Burst”)
1035i/60 Hz
525i/59.94 Hz
1080i/50 Hz
525p/59.94 Hz
1080i/59.94 Hz
625i/50 Hz
1080i/60 Hz
625p/50 Hz
1080p/23.98 Hz
720p/23.98 Hz
1080p/24 Hz
720p/24 Hz
1080p/25 Hz
720p/25 Hz
1080p/29.97 Hz
720p/29.97 Hz
1080p/30 Hz
720p/30 Hz
1080psf/24 Hz
720p/50 Hz
1080psf/23.98 Hz
720p/59.94 Hz
720p/60 Hz
Issue 3, September 2010
Page 44
Model 76D/77 User Guide
Studio Technologies, Inc.
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