Studio Technologies 76D User Manual V.2.02
for Surround
Model 76D Central Controller and
Model 77 Control Console
User Guide
Issue 2, June 2009
This User Guide is applicable for systems consisting of:
Model 76D: serial number M76D-00151 and later with software version 2.02;
Model 77: M77-00151 and later with software version 2.00
© 2009 by Studio Technologies, Inc., all rights reserved
www.studio-tech.com
50230-0609, Issue 2
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for Surround
Table of Contents
Introduction ................................................................... 5
Installation .................................................................... 8
Configuration ................................................................15
Operation ......................................................................31
Technical Notes ............................................................37
Specifications ...............................................................41
Appendix A—Connection Pin-Out Charts ....................43
Appendix B—Sync Sources .........................................44
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Issue 2, June 2009 Model 76D/77 User Guide
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Introduction
What This User Guide Covers
This User Guide is designed to assist
you when installing and using the Model
76D Central Controller and one or more
associated Model 77 or Model 71 Control
Consoles.
Overview
As creating and distributing multi-channel
surround (5.1) and stereo (2-channel) audio
material has become a day-to-day reality,
the ability to simply and effectively monitor
these sources is imperative for recording,
post-production, and broadcast facilities.
And with an “all-digital” world now upon
us, additional monitoring challenges have
arisen. Studio Technologies has addressed
these needs with the StudioComm for Sur
round Model 76D Central Controller and the
Model 77 and Model 71 Control Consoles.
With the all-digital audio inputs and outputs,
support for multiple user control surfaces,
and extensive set of operating resources
it’s a simple task to integrate a monitoring
system into virtually any facility. The carefully selected group of features, including
surround and stereo inputs, multiple preand post-fader outputs, downmix and mute/
solo functions, along with a multi-format
sync input, make the system powerful yet
simple to operate. And by using the best of
contemporary technology, as well as following rigorous design practices, the system’s
audio quality is excellent.
An all-digital StudioComm for Surround
system starts with the Model 77 Control
Console. It’s the system’s “command center”
and is designed to reside at an operator’s
location, allowing fingertip selection of
all monitoring functions. Numerous LED
-
indicators provide complete status information. A 4-digit numeric display indicates the
post-fader monitor output level in real time.
A major strength of the Model 77 is its
ability to configure, under software control,
many important operating parameters. Intended for secondary monitoring locations,
the Model 71 Control Console is a compact user control surface. It provides three
of the most basic functions: a level control,
dim, and reference level.
While many installations will use only one
Model 77 Control Console, up to a total of
four Model 77 or Model 71 Control Consoles can be connected to a Model 76D
Central Controller. This provides multiple
users with full control over a facility’s monitor system. Making installation simple, the
Model 76D provides power for all connect
ed Model 77 or Model 71 units.
The core of this StudioComm for Surround
system is the Model 76D Central Controller. The one-rack-space unit contains all
the audio input, output, processing, and
support circuitry. The Model 76D provides
two surround (5.1) and three stereo audio
inputs. These unbalanced digital inputs are
AES3id/SMPTE 276M-compliant; sources
of this type are ubiquitous in most postproduction and broadcast environments.
The inputs allow a sample rate of up to
192 kHz and a bit depth of up to 24 to be
directly supported. Circuitry associated
with one of the stereo inputs provides
sample rate conversion (SRC) capability, allowing a wide range of digital audio
source to be monitored. Up to 340 milliseconds of input delay can be selected to
compensate for processing delays in an
associated video path. For synchronization
with a master timing reference the Model
76D allows direct connection of a word
-
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clock, DARS (AES11), AES3id, bi-level
video, or tri-level video signal.
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 5 volts peak-to-peak (Vpp) level. For
AES3id operation the impedance is
75 ohms and the level is 1 Vpp.
Great care was taken in designing the
system’s architecture, ensuring that the
character of the audio input signals is
preserved. All audio processing is performed in 32 bits using a high-speed
field-programmable gate array (FPGA)
integrated circuit. A dynamic range of
greater than 123 dB is provided with less
than 1 dB of input-to-output noise added.
The Model 76D occupies one space (1U)
in a standard 19-inch rack. Digital audio
signals are interfaced with the Model 76D
using nine BNC connectors. Monitor output signal connections are made using
one 25-pin D-subminiature connector. One
9-pin D-subminiature connector is used
to connect the Model 76D with up to four
Model 77 or Model 71 Control Consoles. A
second 9-pin “D-sub” connector is used to
interface with remote control signals. AC
mains power is connected directly to the
Model 76D, with an acceptable range of
100 to 230 volts, 50/60 Hz.
Figure 1. Model 76D Central Controller Front Panel
Figure 2. Model 76D Central Controller Back Panel
AC mains input
connection
To/from
Models 77 &
71 Control
Consoles
RS-485 and
remote control
inputs
Digital
monitor
output
connections
connection
Sync
Input
connection
Stereo
Input C
Surround Input B
connections
Control console
status LED
Surround Input A
connections
Sync status
LED
Stereo Input A and
Stereo Input B
connections
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Mute/solo
mode
for Surround
Channel mute/solo
Downmix
Input source
select
Figure 3. Model 77 Control Console Front Panel
Additional Details
The Model 77 provides five buttons and
associated LEDs for selection of the surround and stereo input sources to be monitored. While in most cases only one input
source will be monitored at a time, stereo
input C can be selected for simultaneous
monitoring with one of the two surround
or other two stereo inputs. This allows
the two selected inputs to be combined
(“summed”).
The post-fader surround and stereo monitor output levels can be controlled by way
of a large, easy-to-use rotary control. The
control, actually a digital encoder, allows
level selection in precise 0.5-dB steps. The
auto mute all function causes the postfader surround and stereo monitor output
channels to automatically mute whenever
the output level is set to its minimum position. Using the reference level function, the
post-fader surround and stereo monitor
output levels can be set to a pre-config
ured value. This is provided for audio-withpicture applications that require a specific
-
Monitor output
level display
Post-fader surround
monitor output
• Surround/stereo
• Reference level
• Mute all
• Dim
• Rotary level control
monitor output level. The reference level is
easily configured by taking an electronic
“snapshot” of the desired monitor output
level. For operator confirmation a 4-digit
LED readout can display the level of the
post-fader surround and stereo monitor
output channels. To match the needs of
a facility, it can be configured to display
either the attenuation level or the sound
pressure level (SPL).
The dim function allows the post-fader
surround and stereo monitor output levels
to be reduced by a fixed dB amount. The
dim level is configured from among four
available values. A mute all function allows
all post-fader surround and stereo monitor output channels to be simultaneously
muted. The channel mute/solo section provides individual post-fader surround and
stereo channel monitoring control, allowing
a single channel to be muted or monitored.
Multiple channels can also be simultaneously selected for muting or “soloing.”
A special solo mode is also provided,
called channel pop solo, which offers a
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unique aid in monitoring audio material.
Channel pop solo allows the level of a
single channel to be raised while the level
of the other channel is reduced. This helps
to emphasize the content on one channel
without fully muting the others. Broadcast
applications can benefit from the channel
pop solo mode allowing, for example, the
center channel to be highlighted while still
maintaining some level on the other channels. The amount of level increase—the
“pop”—as well as the amount of attenua
tion can be configured to meet the needs
of specific applications or users.
Two functions allow the input sources to be
checked for level or phase inconsistencies.
The 5.1 to stereo downmix function is used
to create a stereo signal from the selected
surround (5.1) source. The stereo to mono
downmix function allows audio on the left
and right channels to be added (summed)
and monitored on the center output channel. The two downmix functions can be
simultaneously enabled, allowing a surround source to be checked for mono compatibility. The downmix functions always
impact the post-fader surround and stereo
monitor outputs. A configuration setting
allows the pre-fader surround monitor output to be selected for pre- or post-downmix
operation.
For flexibility, the StudioComm for Surround system is designed to easily integrate with equipment such as production
intercom systems, on-air or recording tally
signals, and audio consoles. Two remotecontrol input functions are provided: mute
all and dim. By providing access to these
functions, talkback or slate activity from
an audio console or other communications
system can control the level of the postfader surround and stereo monitor outputs.
-
Installation
In this section you will be installing the
Model 76D Central Controller in an equipment rack. Connections to the audio inputs
and monitor outputs will be made. If desired,
external equipment will be interfaced to
the remote control inputs. A location will be
selected for the first Model 77 Control Console and it will be connected to the Model
76D. AC mains power will be connected to
the Model 76D. For advanced applications
up to three additional Model 77 or Model 71
Control Console units can be connected to
the Model 76D.
System Components
The main shipping carton contains one each
of the following: Model 76D Central Controller, Model 77 Control Console, 9-pin D-sub
interconnecting cable, and user guide. Also
included in the shipping carton is a North
American-standard AC mains cord. Your
dealer or distributor should provide an AC
mains cord appropriate for destinations outside of North America. Any additional Model
77 or Model 71 Control Consoles will be
shipped in separate cartons.
Mounting the Model 76D
The Model 76D Central Controller requires
one space in a standard 19-inch (48.3 cm)
equipment rack. Select a location that is
convenient for making connections to the
audio signals as well as interfacing with
the first (or only) Model 77 Control Console.
A cable is supplied to connect the Model
76D to the Model 77. If the needs of a
specific installation dictate, an alternatelength interconnecting cable can be fabri
cated and used. Secure the Model 76D
into the equipment rack using two mounting
screws per side.
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Audio Connections
Audio connections are made by way of nine
BNC jacks and a 25-pin D-subminiature
connector. All the connectors are located
on the Model 76D’s back panel. Refer to
Figure 2 for a detailed view of the back
panel.
Audio Inputs
Two surround (5.1) and three stereo
(2-channel) digital audio sources can be
connected. All sources can be monitored
using the pre- and post-fader surround and
post-fader stereo monitor output channels.
A one-to-one relationship is maintained
between the input channels and output
channels, i.e., left input to left monitor output, right input to right monitor output,
center input to center monitor output, etc.
(Of course this won’t be true in the case
where the user has enabled the 5.1 to
stereo downmix function.) Stereo input C
is also routed to the stereo input C direct
monitor output.
The audio inputs support digital audio signals with sampling rates of up to 192 kHz
and a word length (depth) of up to 24 bits.
However, all the connected signal sources
must maintain a common sample rate and
timing reference. Having all signals “locked”
together ensures proper handling by the
Model 76D’s all-digital signal path.
There is, however, an exception worth noting. Circuitry associated with stereo input C
has sample rate conversion (SRC) capabil
ity, allowing virtually any digital audio signal
to be connected. Refer to the Technical
Notes section of this guide for a detailed
review of the SRC capability. A signal connected to stereo input C can have an independent sample rate and timing reference
and still be monitored correctly.
-
Nine BNC jacks (female) on the Model
76D’s back panel are used to interface with
the 18 channels associated with the digital
audio signal sources; each BNC connector carries two audio channels. The digital
audio inputs are intended for connection
with unbalanced digital audio sources that
are compatible with the AES3id standard.
In broadcast or post-production environments these signals may also be referred
to as following the SMPTE 276M standard.
This signal type has a nominal impedance
of 75 ohms with a nominal signal level of
1 Vpp. As expected, these digital audio
sources should be provided in the form of
coaxial cables with BNC plugs attached.
Balanced AES3 digital audio signals
can also be used with the Model 76D’s
inputs if external coupling transformers
(“baluns”) are utilized. These impedancematching (110 ohms to 75 ohms) and
level-attenuation transformer assemblies
typically provide a 3-pin female XLR connector on their input and a female BNC
connector on their output.
Monitor Outputs
The 25-pin D-subminiature connector
labeled Digital Monitor Outputs provides
access to the Model 76D’s 16 channels
of digital audio: pre-fader surround, postfader surround, post-fader stereo, and
stereo input C direct monitor outputs. The
pre-fader surround monitor output channels are intended for connection to metering or monitoring equipment that requires
uninterrupted full-level signals. The postfader surround monitor output channels
are intended to connect to the main 5.1
loudspeaker system incorporated in a facility. The post-fader stereo monitor output
is provided to support a separate set of
stereo monitor loudspeakers. The stereo
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input C direct monitor output is essentially
a unity gain copy of the signal connected
to stereo input C. However, the signal does
pass through the sample rate conversion
(SRC) and input delay circuitry. The impact
made by these functions will depend on the
specific input signal and the Model 76D’s
configuration settings.
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
as groups with separate choices available
for the pre-fader surround/stereo input C
direct group and post-fader surround/postfader stereo monitor output group. When a
group is set for AES3 (110 ohms/5 Vpp) the
signals are compatible with AES3 interfaces.
Signals of this type are normally interconnected using 3-pin XLR connectors. When
a group is configured for AES3id (75 ohms/
1 Vpp) the source impedance and signal
level are compatible with the requirements
of AES3id interfacing. These signals are
typically interconnected using BNC connectors. For details on how a Model 77 is used
to select the digital monitor output types
refer to the Configuration section of this
user guide.
A cable assembly with a 25-pin D-sub plug
(male) on one end and the desired connectors on the other end will be used for
connecting to the digital monitor outputs.
The D-subminiature connector follows the
TASCAM® wiring convention, organizing the
25 pins into eight groups of three pins each;
one pin remains unused. Each set of three
pins provides an independent interface.
In the analog world this would allow eight
audio signals to be transported. But with
AES3/AES3id digital audio signals this allows support for 16 audio channels; eight
interfaces each consisting of two audio
channels.
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 con
nector (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.
For compatibility with AES3id unbalanced
digital audio signals connect the D-sub’s
+ terminal as signal high, and both the
– and shield terminals as the signal low/
shield. When terminating to a BNC plug
the D-sub’s + terminal should connect to
the center pin; the – and the shield connections should go to the “body” of the
BNC plug. For optimal operation, it is best
to connect both – and shield together directly on the D-sub plug, rather than at
the BNC end of the interface assembly.
Note that the output circuitry is transformer-coupled so it is possible to just connect
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to the + and – terminals and still experience correct operation. This would leave the
shield connection unterminated.
Refer to Figure 4 or Appendix A for the
exact connection details. Note that unlike
a DA-88-style assembly, the two threaded
fasteners associated with the Model 76D’s
D-sub connector use 4-40 threads. This
complies with the original design standard
for D-sub connectors.
Pre-Fader Surround Monitor Output
The pre-fader surround monitor output
channels are intended to connect to metering, measurement, test, or other signal
monitoring equipment that require uninterrupted, full-level digital audio signal sources.
Post-Fader Surround Monitor Output
The post-fader surround monitor output
channels are designed for connection to
audio amplifiers associated with monitor
loudspeakers or to the inputs of loudspeak
-
ers that contain integrated amplifiers.
TASCAM® Signal Signal
Connections Channel High (+) Low (–) Shield
Pre-Fader L/R 1 24 12 25
Pre-Fader C/LFE 2 10 23 11
Pre-Fader LS/RS 3 21 9 22
Stereo Input C Direct 4 7 20 8
Post-Fader L/R 5 18 6 19
Post-Fader C/LFE 6 4 17 5
Post-Fader LS/RS 7 15 3 16
Post-Fader Stereo 8 1 14 2
Notes: 1) All signals transformer-coupled digital audio;
selectable for AES3 or AES3id compatibility.
2) Connector type on Model 76D is 25-pin
D-subminiature female (DB-25F). Installer must
provide male (DB-25M). Connector uses 4-40
threaded inserts for locking with mating plug.
3) Wiring scheme follows TASCAM DA-88 convention.
Standard DA-88-type wiring harnesses are directly
compatible, with the exception of 4-40 screw threads
being required.
Figure 4. Connections for Monitor Outputs
Post-Fader Stereo Monitor Output
The post-fader stereo monitor output
channels are intended to support a stereo
loudspeaker system, either connecting to
an amplifier associated with a set of loudspeakers or directly to a set of amplified
speakers.
Stereo Input C Direct Monitor Output
The stereo input C direct monitor output
is intended for use in site-specific applications. It provides an uninterrupted, full-level
digital audio signal source.
Sync Input
An external timing reference signal must
be connected to the Model 76D. This synchronization (“sync”) signal must maintain
a stable relationship between itself and the
connected digital audio signals. The actual sync source can be in one of several
forms: word clock, DARS, AES3id, bi-level
video, or tri-level video. The source of the
Model 76D’s sync reference will, in most
cases, be a dedicated sync signal connected to the unit’s sync input. Alternately,
the AES3id-compatible digital audio source
connected to the L/R input of surround A
can also serve as the sync reference. A
configuration choice, described later in
this user guide, is used to select the actual
sync source to be utilized. In this section
of the user guide details will be provided
regarding connection of a dedicated sync
signal to the sync input. This is the recommended method and in most cases should
be utilized.
An overview of the various compatible
timing reference signals might prove
worthwhile. Word clock is a digital signal
that is locked in phase and frequency to
the sample rate of the associated digital
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audio sources. DARS (digital audio reference source) is a timing signal compliant
with the AES11 standard. It’s sometimes
referred to as “AES3-black.” Technically it
is similar to an AES3 or AES3id signal but
is generated specifically as a timing reference signal. Bi-level video sync signals are
typically provided to support NTSC or PAL
broadcast applications, although they’re
also used by some later-generation equipment. Tri-level sync signals are primarily
associated with facilities that support highdefinition (HD) video equipment. These
tri-level signals can be found at numerous
rate combinations, configured to allow for
compatibility with the various video formats. With the wide range of allowable
sync sources proper Model 76D operation
should be easy to obtain. Extensive testing
has been done using many different sync
source types and rates. Interested users
can refer to Appendix B of this user guide
for details.
The external sync reference source should
be connected to the sync input BNC connector located on the Model 76D’s back
panel. For flexibility the input can be configured to be high-impedance (“floating”) or
terminated with an impedance of 75 ohms.
A sync source that is dedicated for use by
the Model 76D’s sync input will typically
have input termination enabled. If the sync
signal connected to the Model 76D is being connected (“multed”) to other inputs it
may be desirable for the termination to be
disabled. A general “rule of thumb” is that
termination should be applied only at the
location of the last physical device using
a sync signal. Refer to the Configuration
section of this guide for details on how to
select the desired termination settings.
Remote Control Inputs
Support is provided for two remote control input functions: remote mute all and
remote dim. The inputs use logic gates,
“pulled up” to +5 volts DC by way of resistors, which are active whenever they are
brought to their logic low state. Inputs of
this type are commonly referred to as GPI
inputs. While the input circuitry is protected
from over-current and static (ESD) discharge, care should be taken to prevent
nasty signals from reaching them. The
inputs are active only when held in the low
state; they can’t be configured to change
state (“latch”) in response to a logic pulse.
A 9-pin D-subminiature connector is used
for the remote control inputs. Refer to
Figure 5 or Appendix A for the exact connection details. Note that pin 4 (remote
common) connects to the Model 76D’s
internal circuit common connection as
well as the Model 76D’s chassis and
mains earth connections. Figure 5 also
shows two spare remote control inputs
(pins 8 and 9). These are provided for
future applications and should remain
unconnected. This connector also allows
Signal Pin Direction
Data + (RS-485/RS-422) 7 Not used
Data – (RS-485/RS-422) 2 Not used
Data Shield 1 Shield
Remote Mute All 5 Input
Remote Dim 6 Input
Remote Spare 1 8 Input
Remote Spare 2 9 Input
Remote Input Common 4 Common
Note: Connector type on Model 76D is 9-pin D-subminiature
female. Connector uses 4-40 threaded inserts for
locking with mating plug.
Figure 5. Connector Pin Out for Remote Control
Inputs
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access to an RS-485 data interface. This
interface is not supported in the Model 76D
and, as such, pins 7 and 2 should remain
unterminated.
Connecting the Model 76D to
the Model 77
A 9-pin female D-subminiature connector,
labeled To/From Control Consoles, is provided on the back panel of the Model 76D
Central Controller. This is used to interface
the unit with Model 77 Control Consoles.
A 9-pin female D-sub connector, labeled
To/From Central Controller, is provided on
the back panel of each Model 77 Control
Console. A cable with 9-pin male D-sub connectors on each end is used to interconnect
the Model 76D with the Model 77 units. A
cable is included in the shipping carton. The
cable implements all nine connector pins in
a one-to-one manner.
Should an interconnecting cable of a different length be required there’s no problem for
one to be fabricated and used. While it can
be wired in a one-to-one fashion supporting all nine pins, only four connections are
required: pin 1 (data +), pin 6 (data –), pin 4
(DC +), and pin 9 (DC –). The Model 76D’s
connector pin-out scheme was designed to
allow creation of an interconnecting cable
which uses commonly available 2-pair audio
cable. This cable, consisting of two twisted
pairs each with an individual shield, is typically sleek, flexible, and available in many
colors. One pair and shield can be used for
the data connections while the other pair
and shield can be used for the DC connections. This implementation has the advantages of providing a shield for the data path
and a more robust common connection (two
conductors including the shield) for the DC
power circuit. Refer to Figure 6 or Appendix
A for details.
Signal Pin Direction
Data + (RS-485) 1 To/From Models 77/71
Data – (RS-485) 6 To/From Models 77/71
Data Shield 2 To/From Models 77/71
DC + (12 V) 4 To Models 77/71
DC – (12 V Return) 9 To Models 77/71
DC Power Shield 5 To/From Models 77/71
Note: Connector type on Model 76D is 9-pin D-subminiature
female (DE-9F). Connector uses 4-40 threaded inserts
for locking with mating plug.
Figure 6. Connections between Model 76D and
Model 77 and Model 71
A few simple calculations are required to
determine the maximum cable length when
connecting a Model 77 to a Model 76D.
The differential transmission scheme used
by the system’s RS-485 interface makes
an interconnection in excess of 1000 feet
(>300 meters) easily possible. The limiting
factor is typically the ability of the wiring
to pass the DC power supplied by the
Model 76D to the Model 77. The Model
76D supplies 12 volt DC with a maximum
current of 500 milliamperes.
The Model 77 requires a minimum of
9 volts DC, 100 milliamperes maximum
for correct operation. (The voltage must be
measured directly at the Model 77’s 9-pin
connector.) So the maximum interconnecting cable length is directly related to the
resistive voltage losses associated with
the two DC-carrying conductors. As the
Model 76D supplies 12 volts and the
Model 77 requires 9 volts minimum, this
directly leads to a 3 volt DC maximum
drop due to the interconnecting cable. Using Ohm’s law it’s quite easy to determine
whether the selected cable will support the
desired interconnection length. Calculate
the voltage drop by multiplying the total
resistance (in ohms) of the proposed cable
by 0.1 (the Model 77’s maximum required
current in amperes). Remember to include
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the resistance in both the DC + and
DC – wires in the figure for the total resistance. If it’s greater than 3 volts your cable
is too long or the wire gauge is too small.
Additional Control Consoles
Some installations may benefit from the
Model 76D’s ability to be controlled by additional control consoles. As expected, at
least one Model 77 Control Console must
be connected to a Model 76D Central Controller. After this requirement has been met
up to three additional Model 77 or Model 71
Control Consoles can also be connected
and powered by the Model 76D.
When connecting multiple control consoles
to a Model 76D all nine pins of each interconnecting cable can be connected in
parallel (“multed”). This will electrically
mult the data and 12 volt DC power signals
between all the units. A custom cable
implementation requires just four pins to
be connected: pin 1 (data +), pin 6 (data –),
pin 4 (DC +), and pin 9 (DC –).
To make installation simple, a “bus” cable
assembly can be created using a short
length of ribbon cable with one male and
multiple female 9-pin D-subminiature insulation-displacement connectors attached.
Then standard 9-pin cables can link the
control consoles with the connectors on
the bus cable.
Refer to the previous paragraphs of this
user guide where the issues involving
Model 76D to Model 77 cable length are
discussed. Note the maximum required
current for a Model 77 is 100 milliamperes
while a Model 71 requires only 35 milliamperes. It’s important to review this information prior to creating the interconnection
scheme to be used for installing multiple
Model 77 units.
AC Mains Power
The Model 76D operates directly from
AC mains power of 100 to 230 V, 50/60 Hz.
Being a “universal input” device, there are
no switches to set or jumpers to install
to match a location’s mains voltage. The
unit uses a 3-pin IEC 320 C14-type inlet
connector to mate with a detachable mains
cord. All units are supplied with a mains
cord that has a North-American standard
plug (NEMA 15L) on one end and an IEC
320 C13 socket on the other. Units bound
for other destinations require that the ap
propriate cord be used. The wire colors
in the mains cord must conform to the
internationally recognized color code and
should be terminated accordingly:
Connection Wire Color
Neutral (N) Light Blue
Line (L) Brown
Protective Earth (E) Green/Yellow
Safety Warning:
The Model 76D does
not contain an AC mains disconnect
switch. As such, the AC mains cord
plug serves as the disconnection
device. Safety considerations require
that the plug and associated outlet be
easily accessible to allow rapid disconnection of AC mains power should
it prove necessary.
As soon as mains power is applied
the Model 76D will perform a power-up
sequence. The two LEDs on the right side
of the front panel will individually light in a
rapid right-to-left test sequence. Then the
LEDs will flash in cadence while the firmware loads into the Model 76D’s main logic
device. After just a few seconds normal
operation can commence and the LEDs
will perform their intended functions. Once
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Issue 2, June 2009 Model 76D/77 User Guide
Page 14 Studio Technologies, Inc.
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