for Surround Model 780-02 Central Controller and Model 790 Control Console User Guide

for Surround Model 780-02 Central Controller and Model 790 Control Console User Guide
for Surround
Model 780-02 Central Controller and
Model 790 Control Console
User Guide
Issue 2, April 2015
This User Guide is applicable for systems consisting of:
Model 780-02: serial number M780-02-00151 and later with
software version 1.00 and higher and FPGA version 4.15 and higher;
Model 790: serial number M790-00151 and later with software version 1.00 and higher
© 2015 by Studio Technologies, Inc., all rights reserved
www.studio-tech.com
50392-0415, Issue 2
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for Surround
Table of Contents
Revision History............................................................ 4
Introduction ................................................................... 5
Installation .................................................................... 8
Configuration ................................................................15
Operation ......................................................................34
Technical Notes ............................................................40
Specifications ...............................................................44
Appendix A—Connection Pin-Out Charts ....................46
Appendix B—Sync Input Sources ................................47
Appendix C—Downmix Formulas .................................48
Model 780-02/790 User Guide
Studio Technologies, Inc.
Issue 2, April 2015
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for Surround
Revision History
Issue 2, April 2015:
1. Revised specifications to reflect final audio performance measurements.
2. Text clarifications.
Issue 1, January 2015:
1. Initial release.
Issue 2, April 2015
Page 4
Model 780-02/790 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 780-02
Central Controller and one or more associated Model 790 or Model 71 Control
Consoles.
Overview
Creating and distributing eight channel
(7.1) surround audio material has become
common for entertainment, cinema, and
allied applications. As such, the ability to
simply and effectively monitor these sources is imperative during the recording and
post-production process. Studio Technologies has addressed these needs with the
StudioComm for Surround Model 780-02
Central Controller and the Model 790 and
Model 71 Control Consoles. With digital
audio inputs, analog monitor output, support for multiple user control surfaces, and
an extensive set of resources it’s a simple
task to integrate a monitoring system into
virtually any facility. The carefully selected
group of features, including two surround
(7.1) and one stereo input, configurable
input-source time delay, LFE low-pass filter,
analog surround (7.1) monitor output, configurable downmix and mute/solo functions,
and bass management, along with a multiformat sync input, make the system powerful yet simple to operate. And by using the
best of contemporary technology, as well
as following rigorous design practices, the
system’s audio quality is excellent.
A StudioComm for Surround system starts
with the Model 790 Control Console. It’s
the system’s “command center” and is
designed to reside at a user’s location, allowing fingertip selection of all monitoring
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Studio Technologies, Inc.
functions. Numerous LEDs provide complete status information. A 4-digit numeric
display indicates the level of the monitor
output. A major strength of the Model 790
is its ability to configure, under software
control, many important operating parameters. Intended for secondary monitoring
locations that don’t require all of the Model
790’s features, 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.
Most installations will use only one Model
790 Control Console. However, up to three
additional Model 790 or Model 71 Control
Consoles can also be connected. This
provides multiple users with control over
a facility’s monitor system. And to make
installation simple, the Model 780-02 provides power for all connected Model 790
or Model 71 units.
The core of this StudioComm for Surround
system is the Model 780-02 Central Controller. The one-rack-space unit contains
circuitry that supports balanced digital
audio inputs, a balanced analog monitor
output, digital audio and control processing, and interfacing for the user control
surface(s). The Model 780-02 provides two
surround (7.1) and one stereo digital audio
inputs. These balanced digital inputs are
AES3-compliant; sources of this type are
ubiquitous in many post-production and
audio facility environments. The inputs
allow a sample rate of 44.1, 48, 88.2 or
96 kHz and a bit depth of up to 24 to
be supported. Circuitry associated with
the stereo input provides sample rate
conversion (SRC) capability, allowing a
wide range of digital audio sources to be
monitored. To compensate with processing
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goal of bass management is very simple:
ensure that the entire audio bandwidth of
all channels can be accurately monitored.
Many loudspeaker systems have inherent
low-frequency limitations, preventing a true
sonic “picture” of the source material from
being presented. To overcome this, the
low-frequency energy from the seven channels associated with the surround inputs
and the two channels associated with the
stereo input can be separated and routed to
the subwoofer (SUB) channel of the monitor output. Several of the bass management
functions can be configured to match the
requirements of specific installations.
delays (latency) associated with associated video displays up to 340 milliseconds
of input delay can be selected. For flexibility, two delay values can be configured,
allowing real-time selection as desired. A
number of different signals can serve as
the Model 780-02’s digital audio timing
reference. For synchronization with a master timing reference a dedicated source of
word clock, DARS (AES11), bi-level video,
or tri-level video can be connected. Alternately, the L/R connection of the actively
selected surround or stereo input source
can serve as the timing reference.
One analog surround (7.1) monitor outputs
is provided. It’s intended for connection to
analog inputs on a monitor loudspeaker
system. Electrically balanced, the monitor
output signals provide low-noise, low-distortion, and high-headroom performance.
Great care was taken in designing the system’s architecture, ensuring that the character of the audio input signals was preserved.
All audio processing, including bass management, is performed in 32-bit logic using
a high-speed field-programmable gate array
(FPGA) integrated circuit. High-performance
integrated circuits are used to perform input,
output, and clocking tasks.
A sophisticated bass management function
is integral to the Model 780-02’s design
and can be enabled if desired. The overall
Figure 1. Model 780-02 Central Controller Front Panel
Control console
status LED
Sync status
LED
Figure 2. Model 780-02 Central Controller Back Panel
AC mains input
To/from
Models 790 &
71 Control
Consoles
Analog
monitor outputs
Sync
input
Stereo
input
Digital surround (7.1)
inputs A & B
Remote control inputs
Issue 2, April 2015
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Model 780-02/790 User Guide
Studio Technologies, Inc.
for Surround
Channel mute/solo
Mute/solo
mode
Downmix
Input source
select
Monitor output
level display
Monitor output
• Surround/stereo
• Reference level
• Mute all
• Dim
• Rotary level control
Figure 3. Model 790 Control Console Front Panel
The Model 780-02 occupies one space
(1U) in a standard 19-inch rack. Digital
audio sources are interfaced with the
Model 780-02 using one 25-pin female
D-subminiature connector and one 3-pin
female XLR connector. A BNC connector
is used to interface with an external sync
source. Analog monitor output signal connections are made using a 25-pin female
D-subminiature connector. One 9-pin female D-subminiature connector is used to
connect the Model 780-02 with a maximum
of four Model 790 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 780-02, with an acceptable range of 100 to 240 V, 50/60 Hz.
Additional Details
The Model 790 provides three buttons
and associated LEDs for selection of the
source to be monitored. The choices are
the two surround inputs and the stereo
input; only one source can be monitored
Model 780-02/790 User Guide
Studio Technologies, Inc.
at a time. It’s interesting to note that while
the surround inputs have an LFE channel
associated with them, the corresponding
monitor output channel is designated as
subwoofer (SUB), rather than LFE. This
terminology was selected to highlight the
fact that this output channel may include
more than just LFE content. The bass
management function, if enabled, will redirect low-frequency energy from the main
channels, combine it with the contents
from the LFE input channel, and route the
combination to the monitor output’s subwoofer (SUB) channel.
An LFE low-pass filter function is provided
as a means of checking the audio content
in the LFE channel of a selected surround
input. The user can enable and disable
the function as required, helping to ensure
that the proper signals are being mixed
to the LFE channel. Having the correct
audio content in the LFE channel can
be critical as the LFE channel is typically
band-restricted during distribution.
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The level of the channels associated with
the monitor output 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 monitor output channels to automatically mute whenever the output level control reaches maximum attenuation. Using
the reference level function, the monitor
output level can be set to a pre-configured
value. This is provided for audio-withpicture 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 user confirmation, the 4-digit
LED display will show the level of the monitor output channels. To match the needs
of a facility, the display can be configured
to show either the attenuation level or the
sound pressure level (SPL).
The dim function allows the monitor output
level to be reduced by a fixed dB amount.
The dim level is configured from among
four available values. A mute all function
allows the monitor output channels to be
simultaneously muted. The input mute/solo
section allows an input channel to be muted or monitored as desired. Multiple channels can also be simultaneously selected
for muting or “soloing.”
Two output mute functions are also provided. One button allows the seven main
channels of the monitor output to be muted. A second button allows the subwoofer
(SUB) channel of the monitor output to be
muted. The output mute functions, along
with the input mute/solo function, allow a
user complete flexibility when checking an
input source and its path to the loudspeaker system. These mute and solo resources
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are crucial in a multichannel environment, especially when signals are passing
through the bass management function.
Three downmix functions allow the selected input source to be checked for compatibility with common audio channel formats.
This can help ensure that surround and
stereo mixes correctly “fold down” into
formats that utilize less channels than the
original. Errors can be quickly identified
and then corrected. The downmix functions, To 5.1 and To Stereo, apply only to
the two surround (7.1) sources. The To
Mono downmix function applies to the
surround and stereo inputs. Several of the
downmix parameters can be configured to
best meet the needs of an application.
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 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
monitor outputs.
Installation
In this section you will be installing the
Model 780-02 Central Controller in an
equipment rack. Connections to the surround and stereo audio inputs and the
surround monitor output 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
790 Control Console and it will be connected to the Model 780-02. AC mains power
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Studio Technologies, Inc.
for Surround
will be connected to the Model 780-02. For
advanced applications up to three additional
Model 790 or Model 71 Control Console
units can be connected to the Model 780-02.
System Components
The main shipping carton contains one
each of the following: Model 780-02 Central Controller, Model 790 Control Console,
9-pin D-subminiature interconnecting cable
(approximately 20 feet (6 meters) in length),
and a 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 790 or Model 71
Control Consoles will be shipped in separate
cartons.
Mounting the Model 780-02
The Model 780-02 Central Controller requires one space (1U) in a standard 19-inch
(48.3 cm) equipment rack. Secure the Model
780-02 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 790 Control
Console. A cable is supplied to connect the
Model 780-02 to the Model 790. If the needs
of a specific installation dictate, an alternatelength interconnecting cable can be fabricated and used.
Audio Connections
Digital audio input connections are made by
way of one 25-pin female D-subminiature
connector and one 3-pin female XLR connector. Analog monitor output connections
are made by way of one 25-pin female Dsubminiature connector. The connectors are
located on the Model 780-02’s back panel.
Model 780-02/790 User Guide
Studio Technologies, Inc.
Refer to Figure 2 for a detailed view of
these connectors.
Audio Inputs
Two balanced digital surround (7.1) and
one balanced digital stereo audio source
can be connected. Users will be able to
monitor them, one at a time, using the
analog monitor output. A one-to-one relationship is maintained between the input
and output channels, i.e., left input to left
monitor output, right input to right monitor output, center input to center monitor
output, etc. (Of course this won’t be true in
the case where the user has enabled one
of the three downmix functions.)
The audio inputs support digital audio
signals with sample rates of 44.1, 48, 88.2
and 96 kHz and a depth (word length) of
up to 24 bits. It’s recommended that 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
780-02’s all-digital signal path.
There is, however, an exception worth
noting. Circuitry associated with the stereo
input has sample rate conversion (SRC)
capability, allowing virtually any stereo digital audio signal to be connected. A signal
connected to the stereo input can have an
independent sample rate and timing reference while still being monitored correctly.
Refer to the Technical Notes section of this
user guide for a detailed review of the SRC
capability.
The Model 780-02’s audio inputs are intended for connection with balanced digital
audio sources that are compatible with the
AES3 standard. This type of signal has a
nominal impedance of 110 ohms and a
nominal signal level of 5 Vpp.
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One 25-pin female D-subminiature connector (DB-25F) is used to interface with the
16 channels associated with surround input
A and surround input B. Each of the eight
connections supports two audio channels.
A wiring assembly prepared for these digital
audio inputs would be identical to that of a
TASCAM®-type (AES59-compliant) input
assembly. A typical assembly of this type
will often have eight 3-pin female XLR
connectors on one end and a 25-pin male
D-subminiature connector (DB-25M) on the
other. Refer to Figure 4 or Appendix A for
details on connecting with the 25-pin female
D-subminiature connector.
Channel
Signal
High (+)
Signal
Low (–)
Shield
Surround Input A L/R
1
24
12
25
Surround Input A C/LFE
2
10
23
11
Surround Input A SL/SR
3
21
9
22
Surround Input A BL/BR
4
7
20
8
Surround Input B L/R
5
18
6
19
Surround Input B C/LFE
6
4
17
5
Surround Input B SL/SR
7
15
3
16
Surround Input B BL/BR
8
1
14
2
Connections
Notes: 1) All signals transformer-coupled digital audio;
balanced AES3 (110 ohms, 5 Vpp) compatible.
2) Connector type on Model 780-02 is 25-pin female
D-subminiature (DB-25F). Installer must provide male
(DB-25M). Connector uses 4-40 threaded inserts for
locking with mating plug.
3) Wiring scheme follows AES59-2012 convention.
Standard TASCAM-type wiring harnesses are directly
compatible, with the possible exception of 4-40 screw
threads being required.
Figure 4. Connections for Surround A and
Surround B Digital Inputs
Note that unlike a TASCAM-type assembly, the two threaded fasteners associated
with the Model 780-02’s D-subminiature
connector use 4-40 threads. This complies
with the original design standard for D-sub
connectors.
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On the Model 780-02 the stereo input uses
a 3-pin female XLR connector for interfacing with a digital audio source. The mating
cable should have a 3-pin male XLR connector wired such that the + signal goes
to pin 2, the – signal to pin 3, and shield
to pin 1.
Unbalanced AES3 digital audio signals
can also be used with the Model 780-02’s
inputs if external coupling transformers
(“baluns”) are utilized. These impedancematching (75 ohms to 110 ohms) and level
step-up transformer assemblies typically
provide a BNC connector on their input
and a 3-pin male XLR connector on their
output.
Monitor Output
The 25-pin female D-subminiature connector on the back panel labeled Analog Monitor Outputs provides access to the Model
780-02’s surround (7.1) monitor output.
The eight output channels are intended for
connection with inputs on a loudspeaker
system that provides seven main channels
and one subwoofer channel.
The monitor output channels are designed
for connection to audio amplifiers associated with monitor loudspeakers or to the
inputs of loudspeakers that contain integrated amplifiers. The outputs are analog,
electronically balanced and will perform
optimally when driving loads of 2000
(2 k) ohms or greater. In most applications
3-pin male XLR connectors will be used to
interface with the inputs on the associated
amplifiers or amplified speakers. In this
case the + terminal would go to pin 2 of
the XLR, the – terminal to XLR pin 3, and
the shield terminal to XLR pin 1.
Model 780-02/790 User Guide
Studio Technologies, Inc.
for Surround
Balanced operation of the monitor outputs
is the preferred connection method but
unbalanced operation does not pose a
problem. To connect to an unbalanced load
connect the + terminal as signal high, and
only the Model 780-02’s shield terminal as
the signal low/shield. Leave the – terminal
unconnected. For correct unbalanced operation, it is important not to connect – and
shield together
A wiring assembly prepared for the Model
780-02’s monitor outputs would typically
be identical to that of a TASCAM-type
output assembly. An assembly of this type
would have a 25-pin male D-subminiature
connector (DB-25M) on one end and eight
3-pin male XLR connectors on the other.
Please refer to Figure 5 for the exact connection details. Again note that unlike a
TASCAM-type assembly, the Model 78002’s D-sub connectors use 4-40 threads.
Channel
Signal
High (+)
Signal
Low (–)
Shield
Left (L)
1
24
12
25
Right (R)
2
10
23
11
Center (C)
3
21
9
22
Subwoofer (SUB)
4
7
20
8
Surround Left (SL)
5
18
6
19
Surround Right (SR)
6
4
17
5
Back Left (BL)
7
15
3
16
Back Right (BR)
8
1
14
2
Connections
Notes: 1) Connector type on Model 780-02 is 25-pin female
D-subminiature (DB-25F). Installer must provide male
(DB-25M). Connector uses 4-40 threaded inserts for
locking with mating plug.
2) Wiring scheme follows AES59-2012 convention.
Standard TASCAM-type wiring harnesses are directly
compatible, with the possible exception of 4-40 screw
threads being required.
Figure 5. Connections for Analog Monitor
Outputs
Model 780-02/790 User Guide
Studio Technologies, Inc.
Sync Input
The Model 780-02 requires a timing reference (sync) source so that the audio input
signals will be interpreted correctly. A configuration setting allows the source of sync to
be selected. The default setting uses the L/R
input of the currently selected input source
which can be either of the surround inputs or
the stereo input. While this is acceptable, audio artifacts (clicks or noise) will typically occur when switching between input sources.
A better method is to connect a dedicated
timing reference signal to the Model 78002’s sync input connector. The connected
sync source must maintain a stable relationship between itself and the connected audio
sources. 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 audio sources. DARS
(digital audio reference source) is a timing
signal compliant with the AES11 standard.
It’s sometimes referred to as “AES3-black.”
Technically it is similar to an AES3 signal
but is generated specifically as a timing
reference signal. Bi-level video sync signals
were originally provided to support NTSC
(United States) and PAL (European) analog broadcast applications, although they
continue to be used by contemporary digital
video equipment. Tri-level sync signals were
primarily associated with facilities that upgraded to support high-definition (HD) video
signals, however the need for this type of
sync signal seems to be waning. The Model
780-02 supports both bi-level and tri-level
signals at numerous rate combinations,
allowing for compatibility with various worldwide video formats.
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With the wide range of allowable sync
sources proper Model 780-02 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.
An external sync reference source should
be connected to the sync input BNC connector located on the Model 780-02’s back
panel. For flexibility the Model 780-02’s
sync input can be configured to be terminated with an impedance of 75 ohms or
be high-impedance (“floating”) so as to
not load the source. A sync source that is
dedicated for use by the Model 780-02’s
sync input would typically want to have
the input termination enabled. If the sync
signal connected to the Model 780-02 is
being connected (“multed”) to other inputs
it may be desirable that the termination be
disabled. (A general “rule of thumb” is that
termination should be applied only at the
location of the last physical device using a
specific sync signal.)
Remote Control Inputs
Support is provided for two remote control input functions: remote mute all and
remote dim. The Model 780-02’s remote
control inputs use logic circuitry, “pulled
up” to 3.3 Vdc by way of resistors, which
are active whenever they are brought to
their logic low state. Inputs of this type are
commonly referred to as GPI inputs. While
the input circuitry is protected from overcurrent and static discharge (ESD), care
should be taken to prevent nasty signals
from reaching them. The inputs are active
only when held in the low state; they can’t
be configured to change state (“latch”) in
response to a logic pulse.
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A 9-pin D-subminiature connector (DE-9F)
is used for the remote control inputs. Refer
to Figure 6 or Appendix A for connection
details. Note that pin 4 (remote common)
connects to the Model 780-02’s internal
circuit common connection as well as to
the Model 780-02’s chassis and mains
earth connections. Figure 6 also shows
two spare remote control inputs (pins 8
and 9). These are provided for future applications and should remain unconnected.
Signal
Pin
Direction
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 780-02 is 9-pin female
D-subminiature (DE-9F). Connector uses 4-40
threaded inserts for locking with mating plug.
Figure 6. Connections for Remote Control
Inputs
Connecting the Model 780-02
to the Model 790
A 9-pin female D-subminiature connector
(DE-9F), labeled To/From Control Consoles, is provided on the back panel of the
Model 780-02 Central Controller. This is
used to interface the unit with Model 790
Control Consoles. Refer to Figure 7 or Appendix A for details. A 9-pin female D-sub
connector (DE-9F) labeled To/From Central
Controller, is provided on the back panel of
each Model 790 Control Console. A cable
with 9-pin male D-sub (DE-9M) connectors
on each end is used to interconnect the
Model 780-02 with the Model 790 units. A
cable, approximately 20 feet (6 meters) in
length, is included in the shipping carton.
Model 780-02/790 User Guide
Studio Technologies, Inc.
for Surround
Signal
Pin
Direction
Data + (RS-485)
1
To/From Models 790/71
Data – (RS-485)
6
To/From Models 790/71
Data Shield
2
To/From Models 790/71
DC + (12 V)
4
To Models 790/71
DC – (12 V Return)
9
To Models 790/71
DC Power Shield
5
To/From Models 790/71
Note: Connector type on Model 780-02 is 9-pin female
D-subminiature (DE-9F). Connector uses 4-40
threaded inserts for locking with mating plug.
Figure 7. Connections between Model 780-02
and Model 790 and Model 71
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 actually required: pin 1 (data +),
pin 6 (data –), pin 4 (DC +), and pin 9
(DC –). The Model 780-02’s connector pinout scheme was designed to allow creation
of an interconnecting cable which uses
commonly available 2-pair audio cable. This
cable, consisting of two twisted pairs each
with an individual shield, is typically small
in diameter, flexible, and available in many
colors. One pair and shield can be used for
the data connection (pins 1 and 6) while the
other pair and shield can be used for the
DC connections (pins 4 and 9). This implementation has the advantages of providing
a shield for the data path and a more
robust common (return path) connection
(two conductors including the shield) for
the DC power circuit.
A few simple calculations are required
to determine the maximum cable length
when fabricating a cable to be used when
connecting a Model 780-02 to a Model 790.
The differential transmission scheme used
Model 780-02/790 User Guide
Studio Technologies, Inc.
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 780-02 to
a Model 790. The Model 780-02 supplies
12 Vdc, 500 milliamperes (mA) maximum.
The Model 790 requires a minimum of
9 Vdc, 100 mA maximum, for operation.
(The voltage must be measured directly at
the Model 790’s 9-pin D-subminiature connector.) So the maximum interconnecting
cable length is directly related to the resistive voltage losses associated with the two
DC-carrying conductors (supporting pins 4
and 9). As the Model 780-02 supplies 12 V
and the Model 790 requires 9 V minimum,
this leads to a 3 Vdc maximum drop due to
the interconnecting cable. Using Ohm’s law
it’s quite easy to determine if a desired cable
length can be supported. Calculate the voltage drop by multiplying the total resistance
(in ohms) of the proposed cable by 0.1 (the
Model 790’s required current in amperes).
Remember to include the resistance in both
conductors (DC + and DC –) when calculating the voltage drop. If the voltage drop in
the cable is 3 V or less it should function
correctly. If it’s greater than 3 V the cable
is too long or the wire gauge is too small.
Additional Control Consoles
Some installations may benefit from the
Model 780-02’s ability to be controlled by
additional control consoles. At least one
Model 790 Control Console must be connected to the Model 780-02 Central Controller. After this requirement has been met a
combination of up to three additional Model
790 or Model 71 Control Consoles can also
be connected to and powered by the Model
780-02.
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When connecting multiple control consoles
to a Model 780-02 all nine pins of each
interconnecting cable can be connected
in parallel (“multed”). Using this arrangement the data and 12 Vdc power signals
between all the units will be connected in
parallel. 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 9-pin male
and multiple 9-pin female 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 780-02 to Model 790 cable length
are discussed. Note the required current
for a Model 790 is 100 mA while a Model
71 requires only 35 mA. It’s important to
review this information prior to selecting or
fabricating the interconnection cables that
will be used when installing multiple Model
790 or Model 71 units.
AC Mains Power
The Model 780-02 operates directly from
AC mains power over a range of 100 to
240 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
Issue 2, April 2015
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destinations will 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 780-02
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.
As soon as mains power is applied the
Model 780-02 will perform a power-up
sequence. The two LEDs on the right side
of the front panel will momentarily light in a
test sequence. Then the two LEDs will flash
in cadence while the firmware loads into
the Model 780-02’s main logic device. After
a few seconds initial system operation will
commence and the two LEDs will perform
their intended functions. Once operating
data is being interchanged with the one or
more connected Model 790 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 790 units will go
through a power-up sequence, lighting
each of its LEDs in succession. Using its
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for Surround
4-digit display, each Model 790 will then
momentarily display its address, its software version, and the main and logic
device software versions of the associated
Model 780-02.
All connected Model 71 units will also go
through a power-up sequence after mains
power is applied to the Model 780-02.
Each of the Model 71’s three LEDs will
light momentarily. After these LEDs have
lit, the device address will be shown briefly
using the dim and reference level LEDs,
as shown in Figure 8 in the Configuration
section. When this is complete the Model
71 will begin normal operation. Its status
LED will light if communication is established with the Model 780-02. 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 implemented properly. Refer to
the Configuration section of this user guide
for details on selecting the device address.
Should an error be detected during the
start-up process the two LEDs located on
the right side of the Model 780-02’s front
panel will remain flashing in cadence. On
the Model 790 units a diagnostic code may
be displayed. Refer to the Technical Notes
section of this user guide for details.
needs of the specific installation. Many of
the configuration parameters will impact
the signal flow in to and out of the Model
780-02 Central Controller. Other parameters affect how the one or more Model
790 Control Consoles will display status
conditions and respond to user commands.
Most of the configuration choices will be
made using a Model 790 Control Console.
However, two configuration choices are
available for any connected Model 71
Control Consoles.
Configurable Parameters
Many StudioComm functions can be configured to meet the exact needs of an
installation. A Model 790 Control Console
is used to display and select the desired
system configuration. Here’s an overview
of what can be configured:
• Model 790 Device Address (must be
unique for each unit!)
• Stereo Input Sample Rate Converter
• Bass Management
• Sync Source
• Sync Input Termination
• Audio-Synced-to-Video Sample Rate
• Reference Level
Only after the Model 780-02 and all connected Model 790 and Model 71 units
have correctly powered up will full system
operation begin.
• Overall Display Mode
Configuration
• Dim Level
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 be revised to meet the
• LFE Downmix Level
Model 780-02/790 User Guide
Studio Technologies, Inc.
• Reference Level in dB SPL
• Auto Reference Level Off
• Remote Inputs
• Input Delay Settings
• Monitor Output Channel Level Offsets
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for Surround
The configuration diagrams, located later
in this section, give details on setting each
parameter. An overview of each configurable parameter is provided in the following
paragraphs.
Entering and Exiting the
Configuration Mode
A small button is located on the back of
each Model 790 Control Console, adjacent
to its 9-pin female D-subminiature connector. On any connected Model 790 unit
pressing and holding its configure button
for two seconds places both this specific
unit and the Model 780-02 into their configuration modes. Other connected Model
790 and Model 71 units will enter a standby
mode. When the Model 780-02 enters its
configuration mode it will immediately mute
the monitor outputs, providing an equipment and speaker protection measure.
When a specific Model 790 has entered the
configuration mode its array of buttons and
LEDs will no longer perform their normal
functions, instead being used to display the
configuration settings and reflect changes
as they are being made.
As a user aid, a Model 790 that has entered
the configuration mode will have its mode
mute and mode solo LEDs (associated with
the input mute/solo section) light in an alternating manner. Other connected Model 790
units will indicate that they have entered the
standby mode by simultaneously flashing
their mode mute and mode solo LEDs.
To leave the configuration mode and return
the system to normal operation requires a
final action to be made. On the Model 790
unit that’s in its configuration mode press
and hold its configure button for two seconds. At this time any configuration changes will be stored in nonvolatile memory and
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normal operation, using the stored configuration settings, will resume.
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 accidental activation
unlikely. We didn’t want normal operation to
cease because someone pushed a Model
790 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 StudioComm system’s operating
parameters to achieve the desired performance. The configuration data is stored
in nonvolatile memory, which is rated for
many thousands of read and write cycles
and a retention time in tens of years. Note
that memory integrated circuits are located
in the Model 780-02 Central Controller as
well as the Model 790 and Model 71 Control Consoles. Only the individual device
addresses are stored in each Model 790
and Model 71. All other configuration parameters are stored in the Model 780-02.
Model 790 Device Address
A unique device address must be assigned
to each Model 790 Control Console that is
connected to a Model 780-02. The address
choices are A1, A2, A3, or A4, with the
default address being A1. As most installations will utilize only one Model 790 its
default setting is appropriate. For installations that use two, three, or four Model 790
units it’s important that each 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
Model 780-02/790 User Guide
Studio Technologies, Inc.
for Surround
setting that must be done on each individual Model 790 unit. All other settings can be
made on any one of the connected Model
790 units. Be sure that any selected address does not conflict with addresses that
are, or will be, assigned to Model 71 units.
Stereo Input Sample Rate
Converter
performance of the associated loudspeaker
system can a plan for the bass management functions be selected.
The bass management function impacts the
analog monitor output channels and by default is disabled. The crossover point of the
seven main channels’ bass management
filters can be selected from among four
choices: 40, 50, 60, or 80 Hz. The default
value is 80 Hz. The slope of the low-pass
and high-pass filters associated with the
seven main channels’ bass management
filters can be, as a group, selected. The
choices are 12 dB-per-octave or 24 dBper-octave with the latter being the default
value. Setting the slopes to different values
(asymmetrical filtering on the seven main
channels) can be appropriate for some
loudspeaker systems.
Circuitry associated with the stereo input
can provide sample rate conversion (SRC)
for digital audio signals connected to
that input. The acceptable input range for
sample rate conversion is very wide, but
is dependent upon the output sample rate.
With an output sample rate of 48 kHz any
signal with a sample rate over a range of 8
to 216 kHz can be properly monitored by
the system. This capability can be especially useful with signals that are not synchronized with respect to the other signals
that are connected to the Model 780-02,
even if their sample rates are 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 applications.
By default SRC is enabled and it’s recommended that it remains that way. However
there might be cases where this resource
isn’t desired and it can be disabled.
The Model 780-02 requires that a designated external timing reference (sync) signal
be defined. Three of the choices—video,
DARS, and word clock—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 input to also serve
as the system’s sync source. This fourth
choice is the default value.
Bass Management
Sync Input Termination
The Model 780-02 incorporates flexible
and sonically excellent bass management
capabilities. One configuration parameter
is used to enable or disable bass management while three others are used to
select the characteristics of the associated
audio filters. While the settings are simple
to make, great care must be taken to first
review the entire monitor system. Only
after obtaining a full understanding of the
The sync input circuitry can be configured
to provide a 75 ohm termination impedance
to a connected source. 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 780-02’s BNC input connector then enabling termination is typically
appropriate. However, if the sync source is
being “shared” by multiple inputs then care
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Studio Technologies, Inc.
Sync Source
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for Surround
must be taken so that the signal is only
terminated by one device. By default sync
termination is enabled.
Audio-Synced-to-Video
Sample Rate
If a video sync signal is connected to the
sync input and video is selected as the
Model 780-02’s timing reference the sample
rate of the connected digital audio signals
must be explicitly specified. In most cases
the default value of 48 kHz will be appropriate. But alternately 44.1, 88.2, or 96 kHz
can also be selected. This setting enables
the internal clock and timing circuitry to correctly interpret the video sync signal’s relationship to the connected audio sources.
Reference Level
For consistent monitoring of audio signals
it’s often beneficial for users to be able
to easily set the monitor output level to a
known value. This is sometimes referred
to as “mixing to 85 dB on the monitors,” but
the exact value will depend on the application. The StudioComm system allows a precise monitor output level to be stored and
then enabled by pressing the Model 790
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. Ensure that the StudioComm system
is in its normal operating mode, not the
configuration mode. Be certain that the
dim, mute all, reference level, downmix,
input mute/solo, and output mute functions are not active. The remote mute all
and remote dim functions must also not
be active.
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3. Use the Model 790 Control Console to
select the input source that contains
the desired reference signal source,
e.g., pink noise. This would typically be
one of the surround inputs rather than
the stereo input.
4. Observing the SPL meter, adjust the
Model 790’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 for two
seconds. Once the configuration mode
has been entered the monitor output
will mute.
6. 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 790’s numeric
display will then show the value of the
new reference level. The value shown
will always be a negative number as it’s
always a value less than the maximum
output level. The reference level button
can now be released.
7. To complete the process the configuration mode must be exited. This
is performed by again pressing and
holding the configuration button for
two seconds. The new reference level
is now stored in the Model 780-02’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
Model 780-02/790 User Guide
Studio Technologies, Inc.
for Surround
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 790’s 4-digit numeric display
can be configured to display the monitor
output level in either an attenuation mode
or an SPL mode. In the attenuation mode
(the default), the output level is shown as
a reduction in level, in dB, relative to the
maximum output level. When the rotary
control is used to set the output level to
its maximum the display will show 0.0. As
the rotary control is turned in the counterclockwise direction the display will show
negative values, reaching –70.0 before the
full mute function automatically mutes the
monitor output.
In the SPL mode the display can be configured to allow the output level to be
presented to users in terms of an actual
sound pressure level (SPL). It is used in
conjunction with the reference level in dB
SPL configuration and the stored reference
level. The SPL mode allows a user to see
a visual representation of the SPL level
that is present in the listening environment.
While it takes a little more care to correctly
implement the SPL display mode, it can
offer an enhanced experience for StudioComm users.
Model 780-02/790 User Guide
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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 monitor output
channels are at their reference level, either
through activating the reference level function or manually adjusting the rotary level
control, the Model 790’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 1.0dB steps. In many applications using the
default value of 85 would be appropriate,
reflecting the widely used audio-for-picture
85 dB monitoring reference level. (Typically
this 85 dB is really 85 dBC, indicating that
a C-weighting filter has been applied to the
measurement.) Other common reference
SPL values, such as 82 dB and 87 dB, are
well within the allowable range.
Auto Reference Level Off
When auto reference level off is enabled,
the function automatically turns the reference level function off if a change is made
to the rotary level control while the reference level function is active. This is provided
strictly as a user convenience that may, or
may not, be desired. The default configuration is for the auto reference level off function to be disabled.
Dim Level
The dim function is used to reduce the
monitor output level by a preset amount.
The reduction is in dB relative to the monitor outputs’ current level. There are four dim
level values available: –10.0, –15.0, –20.0,
and –25.0 dB. The default value is –20.0 dB.
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Remote Mute All
Two configuration choices are associated
with the remote mute all function: disabled
and enabled. The default setting has the
function enabled.
Remote Dim
Two configuration choices are associated
with the remote dim function: disabled and
enabled. The default setting has the function enabled.
LFE Downmix Level
By default, when the To Stereo or the To
Mono downmix functions are active the
LFE channel associated with the selected
surround input is fully attenuated (muted).
This removes LFE content from the “downmixed” signal. In most applications this is
appropriate. However, for special situations
a configuration mode allows the LFE channel to be included. In this scenario, when
the To Stereo downmix function is active,
LFE is reduced in level by 6 dB and routed
to both the left (L) and right (R) monitor
output channels. When in this mode and
the To Mono downmix function is active
the level of the LFE channel is reduced by
6 dB and routed to the center (C) monitor
output channel.
Input Delay
A time delay can be added to the input
signals, allowing compensation for delays
that may be present on associated video
signals. The time delay applies to all input
sources and associated channels and cannot be applied selectively. A configured delay time is referenced to a sample rate of
48 kHz. In the case of input signals with a
sample rate of 48 kHz the delay range is 0
to 340 milliseconds in 1-millisecond steps.
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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 790 will result in
an actual time delay of 60 milliseconds.
For operating flexibility two different input
delay values can be selected and stored
during the configuration process. These
can then be enabled as required by the
user during normal system operation. The
default value for both delay A and delay
B is 0 milliseconds. Typical applications
would require only one input delay to be
configured. But in other cases two different, both non-zero, input delay values can
be selected. This could be appropriate in
applications where multiple video display
systems are being used in the same control room or monitoring facility. Each video
display may exhibit its own processing
latency and audio would need to be “lined
up” accordingly. During normal StudioComm operation a user can select the appropriate input delay for the display system
currently being utilized.
Monitor Output Level Offsets
To provide assistance during room calibration, the relative output levels of the monitor output channels can be adjusted over
a limited range. The eight channels can
be adjusted in 0.5-dB steps over a
±12-dB range. The default, of course, is
0 dB for all channels. During configuration
the displayed value represents the dB level
difference as compared to the nominal
output level. In most cases one channel
should serve as the overall reference level
and not be changed. This is typically the
center channel.
Model 780-02/790 User Guide
Studio Technologies, Inc.
for Surround
This feature is provided primarily for use
when the monitor output channels are connected to loudspeaker systems that don’t
offer a means of “trimming” the input sensitivity of individual channels. Without this
capability, minor adjustments to the output
level of specific loudspeakers to account for
room acoustics wouldn’t be possible.
It’s also possible to use the StudioComm’s
output level offset capability to adjust the
overall monitor output level to allow matching to the input sensitivity of loudspeaker
systems. In this case all of the output channels would be configured to have the same
output level offset setting. For example, the
eight channels could all be configured to
have a –3.5 dB output level offset. However,
great care must be taken when configuring a system in this manner. The dynamic
range or noise floor of the audio signals will
be impacted and settings of greater than a
few dB could lead to poor monitor system
performance.
Restore Factory Defaults
The restore factory defaults function is
provided primarily for factory use. In this
way a system can be quickly set so that its
default settings are selected. While you are
welcome to use this function, be careful so
that your configuration efforts aren’t wasted.
Specifically, be aware that the reference
level is reset to minimum level. All the other
parameters are fairly easy to set up, but
resetting the reference level would require
getting out an SPL meter and a calibrated
signal source. This is a hassle you may not
need!
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Model 71 Control Console
Configuration
Two configuration choices are available on
each Model 71. One is its device address
and the other is the button disable mode. A
configure button is located on the back of
each Model 71 Control Console, adjacent
to the 9-pin female D-subminiature connector. Pressing and holding this button for
two seconds places this specific unit in its
configuration mode; normal operation of the
Model 780-02 and other connected Model
71 and Model 790 units will continue. When
a Model 71 enters its configuration mode
its three LEDs will no longer perform their
usual functions. Instead the status LED will
blink to indicate that configuration mode is
active. Refer to Figure 8 for details.
Device Address
The dim and reference level LEDs will
display the Model 71’s device address. The
rotary level control is used to select the desired device address; the LEDs will respond
accordingly. The device address must be
selected so as not to conflict with the device
address of any other connected Model 71
or Model 790 Control Console. The choices
are A1, A2, A3, and A4. All Model 71 units
have a default device address of A4; Model
790’s units have a default device address
of A1. This ensures that, in most cases,
no change will have to be made. Refer to
Figure 9 for details.
Button Disable
To disable the Model 71’s two buttons,
simultaneously press and hold both the
dim and reference buttons for two seconds.
When the disable request has been recognized the LEDs above both buttons will
flash rapidly. Release the buttons and they
will no longer enable or disable their normal
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functions. To return the buttons to normal
operation simultaneously press and hold
both buttons for two seconds at which time
the two LEDs will flash rapidly.
To leave the configuration mode and return
a Model 71 to normal operation requires
one last action: again press and hold its
configuration button for two seconds. The
selected configuration parameters will be
stored in a nonvolatile memory device that
is located inside this specific Model 71.
Figure 8. Model 71 Control Console Front and
Back Panels
Address
Dim LED
Reference Level LED
A1
OFF
OFF
A2
OFF
ON
A3
ON
OFF
A4
ON
ON
Figure 9. Model 71 Device Address Chart
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Model 780-02/790 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.
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for Surround
Configuration—Model 790 Device Address and Stereo Input
Sample Rate Converter

Press and hold the Mute/Solo
button to display and configure the
Model 790’s device address and
stereo input sample rate converter.
This LED displays the configuration of the stereo input
sample rate converter (SRC). LED L not lit means SRC
is disabled; LED L lit means SRC enabled. Use the button
to change the configuration.
Use the Level control to change this
specific Model 790’s device address.
Address can be either A1, A2, A3, or A4.
See Note below.
Default:
Device address A1.
Stereo input sample rate converter enabled.
Note:
The Model 790’s device address is the only parameter stored in the Model 790. All other parameters are stored
in the Model 780-02.
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Model 780-02/790 User Guide
Studio Technologies, Inc.
for Surround
Configuration—Bass Management
This LED displays the status of the bass management
function. LED LFE lit means bass management enabled;
LED LFE not lit means bass management disabled. Use
the button to change the configuration.
Use these
buttons to select
bass management low-pass
filter slope.
LED Surround A
lit means
24 dB-per-octave;
LED Surround B
lit means
12 dB-per-octave.
Use these
buttons to
select bass
management
high-pass
filter slope.
LED To 5.1
lit means
24 dB-per-octave;
LED To Stereo
lit means
12 dB-per-octave.
Default:

Press and hold
the SUB button
to display and
configure the
bass management
function.
Use the Level control to select
the bass management crossover
frequency. Choices are 40, 50, 60,
or 80 Hz.
Bass management disabled.
Bass management low-pass filter slope 24 dB-per-octave.
Bass management high-pass filter slope 24 dB-per-octave.
Bass management crossover frequency 80 Hz.
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Configuration—Sync Source, Sync Input Termination, and
Audio-Synced-to-Video Sample Rate
This LED displays the configuration of the sync input termination. LED L
not lit means sync input is not terminated; LED L lit means terminated with
75 ohms. Use the button to change the configuration.

Use these
buttons to select
the sync source:
Video
DARS
Press and
hold the Mains
button to display
and select the
sync source,
sync input
termination, and
audio-syncedto-video-sample
rate.
Word Clock
L/R of Currently
Selected Input
Use the level control to adjust the audio-syncedto-video sample rate. Available sample rates are
44.1, 48, 88.2, and 96 kHz.
Default:
Sync source is L/R of currently selected input.
Sync input terminated.
Audio-synced-to-video sample rate 48 kHz.
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Model 780-02/790 User Guide
Studio Technologies, Inc.
for Surround
Configuration—Reference Level
and hold the Reference Level button for 5 seconds to take a “snapshot”
 Press
of the level control’s setting at the time configuration mode was entered. The
Reference Level LED will flash when the button is initially pressed and then
light steadily when the “snapshot” has been taken. See Note below.
Default:
Reference level set for –60.0 dB monitor output level.
Note:
The 5-second button-press delay is a safety feature ensuring that the reference level will not be accidently
changed. To permanently store the new value, you must still exit the configuration mode.
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Configuration—Overall Display Mode, Reference Level
in dB SPL, and Auto Reference Level Off
When the Mute All button is pressed, use the Channel Mute/Solo L and
R buttons to select the overall display mode. LED L lit means attenuation
mode is selected; LED R lit means SPL mode is selected. Use the buttons
to change the configuration.
When the Mute
All button is
pressed, use the
Reference Level
button to enable
or disable auto
reference level
off. When the
Reference Level
LED is lit auto
reference level
off is enabled.
Press and hold the Mute All button to
 display
and set the overall display mode,
the reference level in dB SPL, and auto
reference level off.
Default:
When the Mute All button is pressed,
use the Level control to adjust the
reference level in dB SPL.
Attenuation display mode selected.
85.0 dB SPL reference level.
Auto ref level off disabled.
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Model 780-02/790 User Guide
Studio Technologies, Inc.
for Surround
Configuration—Dim Level, Remote Mute All, and Remote Dim
This LED displays the configuration of remote
mute all. LED L not lit means remote mute all
is disabled; LED L lit means enabled. Use the
button to change the configuration.
This LED displays the configuration of remote
dim. LED C not lit means remote dim is disabled;
LED C lit means enabled. Use the button to
change the configuration.
Use these
buttons to select
the dim level:
–10 dB
–15 dB
–20 dB
–25 dB
Press and hold the Dim button to
 display
and select the dim level,
remote mute all, and remote dim.
Default:
–20 dB dim level.
Remote mute all enabled.
Remote dim enabled.
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for Surround
Configuration—LFE Downmix Level
Use this button to select the LFE
downmix level when the To Stereo
or To Mono downmix functions are
active. LED LFE not lit means full
attenuation; LED LFE lit means –6 dB.

Default:
Press and hold the To Mono button to display and confirm
the LFE downmix level.
LFE downmix level full attenuation when To Stereo or To Mono downmix functions active.
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Model 780-02/790 User Guide
Studio Technologies, Inc.
for Surround
Configuration—Input Delay Settings

Press and hold the
Stereo button to
display and select
input delay A.

Press and hold the
To 5.1 button to
display and select
input delay B.
Use the level control to adjust the input delay.
Range is from 0 to 340. The display shows
delay in milliseconds at 48 kHz sampling
rate. The value is scaled up or down for other
sample rates.
Default:
Input delay 0 milliseconds for both A and B.
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Studio Technologies, Inc.
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Configuration—Monitor Output Level Offsets

Press and hold
the R button
to configure
the surround R
level offset.

Press and hold
the C button to
configure the
surround C
level offset.

Press and hold
the LFE button
to configure
the SUB level
offset.

Press and hold
the SL button
to configure
the surround
SL level offset.

Press and hold
the SR button
to configure the
surround SR
level offset.

Press and hold
the BL button
to configure the
surround BL
level offset.


Press and hold the
L button to configure the surround L
level offset.
Press and
hold the
BR button
to configure the
surround
BR level
offset.
Use the level control to adjust the monitor
output level offsets. The range is –12.0 to
12.0 in 0.5-dB steps.
Default:
0.0 dB monitor output level offsets.
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Model 780-02/790 User Guide
Studio Technologies, Inc.
for Surround
Configuration—Restore Factory Defaults
and hold both the LFE Low-Pass and Dim buttons for 5 seconds to
 Press
restore Model 780-02 and Model 790 factory defaults. Once defaults have been
restored, the associated LEDs will light. After the buttons are released, configuration mode will be exited and normal operation will resume. See Note below.
Factory Defaults:
Device address A1.
Stereo input sample rate converter enabled.
Bass management disabled.
Bass management low-pass filter slope 24 dB-per-octave.
Bass management high-pass filter slope 24 dB-per-octave.
Bass management crossover frequency 80 Hz.
Sync source is L/R of currently selected input.
Sync input terminated.
Audio-synced-to-video sample rate 48 kHz.
Reference level set for –60.0 dB 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.
LFE downmix level full attenuation when To Stereo or
To Mono downmix functions active.
Input delay 0 milliseconds for both A and B.
0.0 dB monitor output level offsets.
Warning: Each Model 790 unit must have a unique address. Restoring factory defaults will reset only this specific
Model 790 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 780-02/790 User Guide
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Issue 2, April 2015
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for Surround
Operation
Now that you’ve installed and configured
the StudioComm system you’re ready to
go. You should find operation very easy.
However, taking time to review and understand this section of the user guide may
prove valuable.
Upon AC mains power up the system
will return to the last operating condition,
including the selected source, downmix
mode, etc. As a precaution, however, the
monitor output level will always return to
its minimum value. The rotary level control
or the reference level button must then be
used to set the level of the monitor output
to the desired level.
Model 780-02 Central
Controller
The Model 780-02’s front panel contains
two LEDs. The control console status LED
will light whenever the Model 780-02 is
communicating with the one or more connected Model 790 or Model 71 units. If the
control console status LED is flashing it indicates that the 12 volt DC output provided
to support the connected control consoles
is in its short-circuit or over-current condition. The control console status LED will
not light when a Model 790 is in the configuration mode or when the Model 790
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 780-02. A flashing
sync status LED indicates that a valid sync
signal is not being received. The timing
reference can be, depending on how the
system is configured, an externally supplied timing (sync) reference or the L/R
input of the selected input source.
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Control Consoles
StudioComm for Surround operation is
controlled using a combination of up to
four Model 790 or Model 71 Control
Consoles that have been connected. Two
system functions can also be controlled
by means of the remote control inputs.
Model 790 Control Console
To make things easy to describe, the Model 790’s operator functions are divided into
six main groups: input source selection,
downmix, monitor output general functions,
input mute/solo, display and display mode,
and remote control inputs.
Any change made to any one Model 790
unit will be reflected in the LEDs and displays on all the connected units. Note that
all control consoles function simultaneously—there is no priority of one unit over
the others.
Input Source Selection
To select an input source press one of
the three input source buttons. The corresponding LED will light to indicate that the
input has been selected. Only one source
can be selected for monitoring at any one
time.
Downmix
Three downmix functions allow users to
perform “real-world” audio format compatibility checks. The To 5.1 function allows
a 7.1 surround source to be checked for
compatibility with 5.1 surround playback
systems. When the function is active a
7.1 surround source is reproduced on
the left (L), right (R), center (C), surround
left (SL), surround right (SR), and subwoofer (SUB) monitor output channels.
The To Stereo downmix function allows
Model 780-02/790 User Guide
Studio Technologies, Inc.
for Surround
a 7.1 surround source to be “folded down”
(mixed) to stereo. The resulting signal is reproduced on the left (L) and right (R) monitor output channels. The To Mono function
allows a 7.1 surround or stereo source to
be converted to a single monaural channel.
The resulting signal is reproduced on the
center (C) monitor output channel.
Using the downmix functions simply requires pressing the desired button. Each
buttons will always “latch” the function on
and off. An LED, located adjacent to each
button, will light whenever its respective
function is active. For details on the exact
actions performed by the three downmix
functions refer to Appendix C at the end
of this user guide.
Monitor Output General
Functions
Four buttons and one rotary control are
associated with the monitor output. The
buttons control operation of the reference
level, mute all, dim, and LFE low-pass filter
functions. In addition the LFE low-pass
filter button can be used to enable the display of the current sample rate. The rotary
level control is used to manually set the
monitor output level.
Reference Level
The reference level button sets the monitor output level 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.
The StudioComm’s default reference level
Model 780-02/790 User Guide
Studio Technologies, Inc.
is –60.0 dB so “out of the box” the Model
790 will display –60.0 when reference level
mode is enabled.
How the rotary level control functions
whenever the reference level mode is
active depends on a configuration setting.
If the auto reference level off function is
disabled turning the rotary level control will
have no impact on the reference level function; it will remain active. If the auto reference level off function has been enabled
turning the rotary level control will cause
the reference level function to automatically turn off.
The LED associated with the reference
level button can also serve as a calibration aid. If the reference level mode is not
active, whenever the monitor output level
is selected to be 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 monitor output 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
monitor output to fully 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.
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Dim
The dim function is provided for user convenience, allowing the monitor output level to
be reduced by a fixed amount. The Model
790’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 monitor output level.
When dim is active the monitor output level
reduction will apply no matter whether the
level is being set by the rotary level control or by the reference level button. The
LED associated with the dim button will
light whenever dim is active. If dim mode is
enabled via the remote dim function the dim
LED will flash.
It’s worth using a few sentences to discuss the auto dim off function. Whenever
dim is enabled due to the dim button being pressed, and the rotary level control is
active (reference level mode is not active),
changing the setting of the rotary level
control will automatically turn off dim. The
auto dim off function is a unique attempt
at protecting the aural health of users. No
longer will there be a heart-stopping blast of
audio when the dim button is pressed, supposedly to enable dim, but actually turning
dim off because it was already enabled. It’s
hard to explain unless you’ve experienced
this in person—trust us, this situation can
and does happen!
Note that the auto dim off function is not
active whenever dim is enabled due to the
remote dim function being active. This allows remote control equipment, such as a
talkback system, to reliably dim the monitor
outputs.
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LFE Low-Pass Filter
The LFE low-pass filter function is provided to emulate the processing done by
some distribution formats to the signal
present on an LFE channel. Unlike the
seven main surround channels, an LFE
channel is typically bandwidth restricted
to save digital “bits.” It’s important that an
audio mix maintains its integrity when such
LFE bandwidth restrictions are in place.
When enabled the LFE low-pass filter
function applies a filter with a –6 dB cutoff
frequency of 120 Hz and a slope of 48 dBper-octave to the selected surround input
source. To enable the LFE low-pass filter
function simply press the LFE low-pass
button. The associated LED will light when
the filter is active in the LFE audio path.
Philosophy dictates how the filter function
should be used. The function can be used
as a final “double check” to ensure that
material will maintain overall integrity when
digitally processed. Enabling the filter during a final listening session should find the
spectral content remaining constant. If the
mix is impacted, content has been incorrectly routed to the LFE channel! It’s also
acceptable to leave the filter enabled at all
times. This will ensure that an audio mix
will “hold up” when processed. However,
this may mask content remaining in the
LFE channel which, although it won’t be
present after processing, may be confusing to mastering engineers or other personnel who monitor the original source
material.
Displaying the Current Sample Rate
The LFE low-pass filter button is also used
to display the system’s current sample rate
value. Pressing and holding the LFE lowpass button will cause the current sample
rate value to be shown on the 4-digit
Model 780-02/790 User Guide
Studio Technologies, Inc.
for Surround
display. The possible values displayed will be
44.1, 48.0, 88.2, or 96.0. This can be useful during troubleshooting or just for general
interest. Once the button is released normal
display operation will resume.
Rotary Level Control
The rotary level control is used to manually adjust the monitor output level. The
level control provides the ability to adjust
the monitor output level over a 70-dB range.
Technically, the rotary level control is a 24step-per-revolution mechanical encoder.
The amount of level change in dB per step
(per “click”) will depend on how quickly the
control is turned. When rotated slowly, each
step represents a 0.5-dB change in level. In
this case, to traverse the entire level range
would require rotating the control more than
five full turns. But the Model 790’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 to be less than
–70.0 dB, the 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
monitor output level. It’s also not active
whenever the reference level function is
active, except if the auto reference level
off function has been enabled. If the dim
function is active, turning the rotary control
will automatically disable the dim function.
Model 780-02/790 User Guide
Studio Technologies, Inc.
Input Mute/Solo
The input mute/solo functions allow specific input channels to be selected for individual or group mute or “solo” monitoring.
The functions take place electrically “after”
the input source selection and input delay
functions but “before” the LFE low-pass filter, downmix, output level, and output mute
functions.
The input mute/solo mode and input
mute/solo channel buttons, along with associated LEDs, work together to provide
excellent operating flexibility. The input
mute/solo mode button allows the user to
select between the mute and solo functions. Going from mute mode to solo mode,
or vice-versa, clears all active mutes or
solos. Pressing the mode button twice
is a legitimate means of quickly clearing
muted or soloed channels. To mute or solo
a channel simply requires pressing one of
the eight input 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.
LEDs associated with a muted or soloed
channel will light to indicate that the function is active.
Output Mute
The two buttons associated with the output
mute function provide a means of directly
muting the monitor output channels. These
serve as an aid in observing the performance of the loudspeaker system. The
output mute function organizes the monitor output channels into two groups: the
main channels (mains) and the subwoofer
(SUB). The mains group consists of the
seven main output channels: left (L), right
(R), center (C), surround left (SL), surround right (SR), back left (BL), and back
right (BR). The SUB group consists of only
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the subwoofer (SUB) output channel. Two
buttons and associated LEDs are used to
control the output mute function. Both
buttons function in a push-on/push-off
manner.
It may be confusing at first to imagine why
the output mute buttons are important. The
reason, like the input mute/solo function,
is bass management. The input mute/solo
function allows observation of the channels
associated with the surround and stereo
inputs. But soloing a single channel, such
as the left input of surround A, may result
in audio content coming out of the system
and being reproduced by both the left (L)
and subwoofer (SUB) loudspeakers. By
maintaining the left channel in the input
solo mode, a user can activate the output
mute function to independently mute the
left (L) and subwoofer (SUB) output channels as desired.
Input Delay
Two input delay settings, A and B, can be
selected and saved during system configuration. These are provided for aligning the audio input signals with latencies
(delays) associated with video processing
and display systems. During normal operation a user can select to have either input
delay A or input delay B active. The input
mute/solo mode button, the output mute
SUB button, and the 4-digit display are
used to select and display the input delay.
When the mute/solo button is pressed and
held the LED associated with the output
mute SUB button indicates whether input
delay A or input delay B is active. The LED
will be lit when input delay B is active.The
4-digit display will show the active delay
time in milliseconds referenced to a 48 kHz
sample rate. The delay time will “scale”
depending on the actual sample rate at
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which the Model 780-02 is operating.
While pressing and holding the mute/solo
button the output mute SUB button can
be pressed to change the selected input
delay. Refer to Figure 10 for details. The
selected input delay will be stored in nonvolatile memory such that a power-down/
power-up cycle will not change the active
selection.
Display and Display Mode
The Model 790’s 4-digit LED display shows
the 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 790 has been
configured.
Display in dB of Attenuation
If configured for the attenuation mode the
display will show the monitor output level
as an attenuation value in reference to
the maximum output. This is in the form
of 0.5-dB steps less than the maximum
of 0.0 dB. So a display of –40.5 would
indicate that the 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 790 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 loudspeaker system is presenting to users. (Typically, the level value
would actually be in dBC, the C-weighted
Model 780-02/790 User Guide
Studio Technologies, Inc.
for Surround

During normal operation, press and hold the Mute/Solo button
to view and change the input delay setting.
This LED displays the current
setting of the input delay.
LED not lit means input delay A
is selected; LED lit means input
delay B is selected. Press the
button to change the setting.
The display shows the currently
selected input delay in milliseconds.
Figure 10. Selecting the input delay
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.
activated, the LED will change from being
steadily lit to flashing.
Remote Control Inputs
The Model 71 Control Console provides a
rotary level control, two pushbutton switches, and three LEDs for control and status
display. The rotary level control allows
adjustment of the monitor output level.
Two buttons, along with associated LEDs,
provide access to the dim and reference
level functions. A status LED lights steadily
whenever normal Model 71 operation is
taking place.
As previously discussed in the Installation section of this user guide, two remote
control signals can be connected to the
Model 780-02. The functions are remote
mute all and remote dim. When an external
signal activates remote mute all the LED
on the Model 790 associated with the mute
all button will flash. If mute all was already
active when the remote mute all function is
Model 780-02/790 User Guide
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When an external signal activates remote
dim the LED on the Model 790 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
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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 790 and
Model 71 units. And, as expected, changes
made using a Model 790 will be reflected
in the Model 71’s LEDs.
In some applications it may be desirable to
disable operation of a Model 71’s dim and
reference buttons. An example could be
where non-technical personnel are allowed
only to use the rotary level control. A configuration parameter, previously described
in the Model 71 Control Console Configuration section of this user guide, allows
button operation to be disabled.
Rotary Level Control
The rotary level control is used to manually adjust the monitor output level. Its
operating characteristics are identical to
the rotary control in the Model 790 Control
Console, discussed earlier in this section.
Dim
The dim function allows the monitor output
level to be reduced by a fixed amount. Its
operating characteristics are identical to
those of the Model 790 Control Console,
discussed earlier in this section.
An indication is provided should the dim
button be pressed when button operation
has been disabled. Its associated LED will
flash briefly but no operating change will
occur. The LED will continue to display the
status of the dim function as selected by
other Model 790 and Model 71 units.
Reference Level
The reference level button sets the monitor output level to the preset value. The
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operating characteristics are identical to
those of the Model 790 Control Console,
discussed earlier in this section.
An indication is provided should the reference button be pressed when button
operation has been disabled. The associated LED will flash briefly but no operating
change will occur. The LED will continue
to display the status of the reference level
function as selected by other Model 790
and Model 71 units.
Technical Notes
Loss of Sync
The Model 780-02 relies on an external
timing reference (sync) source for proper
operation. This can be in the form of an
AES3, word clock, DARS (AES11), bi-level
video, or tri-level video reference signal. In
many cases the sync signal will be connected to the sync input BNC connector
located on the Model 780-02’s back panel.
Alternately, a configuration choice allows
the L/R input of the currently selected input
source to also serve as the system’s timing
reference. Whenever a valid sync signal
has been connected to the Model 780-02
the sync status LED, located on the unit’s
front panel, will light.
If a valid sync signal is not present several visual indications are provided. On
the Model 780-02 the sync status LED will
flash. On all connected Model 790 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 780-02’s sync status LED will
light steadily. On the Model 790 units the
Model 780-02/790 User Guide
Studio Technologies, Inc.
for Surround
word sync will momentarily be displayed
followed by a brief display of the active
sample rate. The sample rate will display
as 44.1, 48.0, 88.2, or 96.0, reflecting the
impact of the sync source rate and the
Model 780-02’s configuration.
5. Displays Model 780-02’s main software
version
If during normal operation the sync source
changes from one valid rate to another
a visual indication is provided. On the
Model 790 units the new sample rate—
44.1, 48.0, 88.2, or 96.0—will momentarily
be displayed.
After a successful system power-up
sequence normal operation will then
commence.
Power Down
Care was taken in the Model 780-02’s
design to minimize the chance that objectionable clicks, pops, or other obnoxious
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 will automatically mute.
Power-Up Messages
Upon mains power being applied to the
Model 780-02 all connected Model 790
units will go through a power-up sequence.
The sequence starts by each of the individual LEDs lighting in a “walk-through”
sequence. Then the 4-digit display tests
all its LED segments. Finally, a set of
messages provide details on the specific
Model 790 and connected Model 780-02
software versions:
1. Displays 790
2. Displays Model 790’s software version
3. Displays Model 790’s unit address
(A1, A2, A3, or A4)
4. Displays 780
Model 780-02/790 User Guide
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6. Displays FPgA
7. Displays Model 780-02’s logic device
(FPGA) software version
Error Codes Err1 and Err2
Should a problem be encountered during
power up one of two error codes may show
on the Model 790’s 4-digit display. If Err1
displays it indicates that communication is
not taking place with the Model 780-02. The
most likely cause would be incorrect wiring
of the data pair linking the two units. Err2
indicates that the Model 780-02 is having
problems with its internal logic device.
(A high-speed field-programmable gate
array (FPGA) serves as the digital “heart”
of the Model 780-02 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 Err2 continues to be displayed
the Model 780-02 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.
Error Code Err3
If a digital audio signal with a sample rate
of other than 44.1, 48, 88.2, or 96 kHz is
connected Err3 will display and the mute
all function will be automatically enabled.
In this scenario, selecting a different source
that has a sample rate of 44.1, 48, 88.2,
or 96 kHz will return the system to normal
operation.
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Sample Rate Conversion
(SRC)
Circuitry associated with the stereo input
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
780-02’s internal timing. While it would be
nice to proclaim that the engineers at Studio Technologies came up with a unique
and exotic circuit to perform this function it’s
really not the case. Several semiconductor
companies provide “single-chip” SRC solutions and an excellent one from AKM was
selected for the Model 780-02. The technical capabilities of the Model 780-02’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 780-02’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 780-02’s monitor output sample rate is determined by the
selected timing reference (sync) signal and,
if required, a configured value. If a word
clock, DARS (AES11), or AES3 signal is
the designated sync source its rate will be
the Model 780-02’s output sample rate. If a
video sync signal is connected, the Model
780-02’s sample rate is selected as part of
the configuration process.
So in practice what can the SRC function
accomplish? If the Model 780-02’s sample
rate is 48 kHz a signal connected to the
stereo input can have a sample rate from 8
to 216 kHz. Or, as another example, if the
Model 780-02’s sample rate is 96 kHz a signal connected to the stereo input can have
its sample rate range from 16 to 216 kHz.
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As useful as allowing one sample rate to
be converted to another, it may be the ability of the Model 780-02’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 780-02 and all of its normally connected input signals will be “locked” to a
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 the stereo input will cause the SRC
function to “lock” it to the Model 780-02’s
rate, thus allowing it to be monitored over
the loudspeaker system.
Model 780-02 to Control
Console Connections
Figure 7 gives a detailed description of
the signals that connect the Model 78002 Central Controller to the one or more
Model 790 or Model 71 Control Consoles.
The Model 780-02 provides 12 volts DC
for use by the control console’s circuitry.
The output current is limited to 100 mA,
minimizing the chance that a short-circuit
condition will damage the Model 780-02’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 780-02
communicates with each Model 790 and
Model 71 unit 20 times per second, receiving button and rotary level control information and sending LED and 4-digit display
status data.
Model 780-02/790 User Guide
Studio Technologies, Inc.
for Surround
“Hot” Disconnection of
Control Consoles
There’s no problem relocating one or more
Model 790 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
780-02 Central Controller will mute the
internal digital audio channels as well as
saving the current operating parameters.
No clicks, pops, or other noises will occur
when the Model 790 or Model 71 units are
again connected. The control consoles
will go through their standard power-up
sequence and then normal operation will
resume.
Model 780-02/790 User Guide
Studio Technologies, Inc.
Issue 2, April 2015
Page 43
for Surround
Specifications
Model 780-02 Central Controller
General Audio:
Supported Sample Rates: 44.1, 48, 88.2, and
96 kHz
Word Length: 24 bits maximum
Internal Processing: 32 bits
Input-to-Output Latency: two samples (e.g., 0.042
milliseconds @ 48 kHz sample rate)
Digital Audio Inputs: 3 (18 audio channels total)
Configuration: two surround (7.1) and one stereo
Type: balanced AES3 (110 ohms, 5 Vpp)
Connector—Surround Inputs: 25-pin female
D-subminiature (DB-25F), AES59-2012-compliant
Connector—Stereo Input: 3-pin female XLR
Sample Rate Conversion (SRC):
Application: available on the stereo input
Input Sample Rate Range: 8 to 216 kHz, limited
to 1/6 to 6 times the output sample rate
Frequency Response:
20-20 kHz, ±0.1 dB @ 48 kHz sample rate;
10-40 kHz, ±0.4 dB @ 96 kHz sample rate
Dynamic Range: 119 dB, A-weighted
Distortion (THD+N): < 0.001%, 20-22 kHz, level
control at full, 22 kHz bandwidth
Crosstalk: –110 dB, ref –1 dBFS, 20 kHz
Connector: 25-pin female D-subminiature (DB-25F),
AES59-2012-compliant
Monitor Output Level Offsets: each channel independently adjustable in 0.5-dB steps over a ±12-dB
range
Bass Management:
Crossover Frequency and Type: –6 dB @ 40, 50,
60, or 80 Hz, symmetrical for low-pass and high-pass
filters, maximally flat
Filter Slope: 12 dB-per-octave or 24 dB-per-octave
Overall Operation: on/off selectable
Downmix Functions: To 5.1, To Stereo, and
To Mono
Latency: 1 millisecond, nominal
Control Console Interface:
Type: RS-485, 115.2 kbit/s, 8-1-N
LFE Input Channel Low-Pass Filter: –6 dB @
120 Hz, 48 dB-per-octave, on/off selectable
Power: 12 Vdc, 500 mA maximum
Polling Interval: 80 milliseconds, nominal
Configurable Input Delay: 0 to 340 milliseconds @
48 kHz sample rate (scales up or down depending
on actual sample rate)
Connector: 9-pin female D-subminiature (DE-9F)
Sync Source: configured to follow L/R of currently
selected input or signal connected to sync input
Type: 3.3 Vdc logic, activates on closure to system
common
Sync Input:
Compatible Sources: word clock, DARS (AES11),
bi-level video, tri-level video
Connector: 9-pin female D-subminiature (DE-9F)
Jitter: 4 ns pp maximum
Connector: BNC (per IEC 60169-8 Amendment 2)
Termination: 75 ohms, selectable on/off
Analog Monitor Outputs: 8
Configuration: organized as one surround (7.1)
Remote Control Inputs: 2
Functions: remote mute all, remote dim
AC Mains:
Requirement: 100 to 240 V, +10/–15%, 50/60 Hz,
15 W maximum
Connector: 3-blade, IEC 320 C14-compatible
(mates with IEC 320 C13)
Type: electronically balanced, source impedance
200 ohms
Dimensions:
19.00 inches wide (48.3 cm)
1.72 inches high (4.4 cm)
7.00 inches deep (17.8 cm)
Nominal Level: +4 dBu @ –20 dBFS input source
and level control at maximum setting
Mounting: one space (1U) in a standard 19-inch
rack
Maximum Level: +24 dBu into 2000 (2 k) ohms
or greater
Weight: 3.6 pounds (1.6 kg)
Issue 2, April 2015
Page 44
Model 780-02/790 User Guide
Studio Technologies, Inc.
for Surround
Model 790 Control Console
Application: up to four Model 790 Control
Consoles can be connected to a Model 780-02
Central Controller
Power: 12 Vdc nominal (9 Vdc minimum), maximum current 100 mA, provided by Model 780-02
Central Controller
Control Data:
Type: RS-485
Data Rate/Format: 115.2 kbit/s, 8-N-1
Connector: 9-pin female D-subminiature (DE-9F)
Dimensions (Overall):
7.20 inches wide (18.3 cm)
2.20 inches high (5.6 cm)
5.40 inches deep (13.7 cm)
Weight: 1.7 pounds (0.8 kg)
Model 71 Control Console
Application: up to three Model 71 Control
Consoles can be connected to a Model 780-02
Central Controller
Power: 12 Vdc nominal (9 Vdc minimum), maximum current 35 mA, provided by Model 780-02
Central Controller
Control Data:
Type: RS-485
Data Rate/Format: 115.2 kbit/s, 8-N-1
Connector: 9-pin female D-subminiature (DE-9F)
Dimensions (Overall):
3.20 inches wide (8.1 cm)
2.20 inches high (5.6 cm)
4.10 inches deep (10.4 cm)
Weight: 0.8 pounds (0.4 kg)
Specifications and information contained in this
User Guide subject to change without notice.
Model 780-02/790 User Guide
Studio Technologies, Inc.
Issue 2, April 2015
Page 45
for Surround
Appendix A—Connection Pin-Out
Charts
Channel
Signal
High (+)
Signal
Low (–)
Shield
Surround Input A L/R
1
24
12
25
Surround Input A C/LFE
2
10
23
Surround Input A SL/SR
3
21
Surround Input A BL/BR
4
Surround Input B L/R
Channel
Signal
High (+)
Signal
Low (–)
Shield
Left (L)
1
24
12
25
11
Right (R)
2
10
23
11
9
22
Center (C)
3
21
9
22
7
20
8
Subwoofer (SUB)
4
7
20
8
5
18
6
19
Surround Left (SL)
5
18
6
19
Surround Input B C/LFE
6
4
17
5
Surround Right (SR)
6
4
17
5
Surround Input B SL/SR
7
15
3
16
Back Left (BL)
7
15
3
16
Surround Input B BL/BR
8
1
14
2
Back Right (BR)
8
1
14
2
Connections
Notes: 1) All signals transformer-coupled digital audio;
balanced AES3 (110 ohms, 5 Vpp) compatible.
2) Connector type on Model 780-02 is 25-pin female
D-subminiature (DB-25F). Installer must provide male
(DB-25M). Connector uses 4-40 threaded inserts for
locking with mating plug.
3) Wiring scheme follows AES59-2012 convention.
Standard TASCAM-type wiring harnesses are directly
compatible, with the possible exception of 4-40 screw
threads being required.
Connections
Notes: 1) Connector type on Model 780-02 is 25-pin female
D-subminiature (DB-25F). Installer must provide male
(DB-25M). Connector uses 4-40 threaded inserts for
locking with mating plug.
2) Wiring scheme follows AES59-2012 convention.
Standard TASCAM-type wiring harnesses are directly
compatible, with the possible exception of 4-40 screw
threads being required.
Connections for Analog Monitor Outputs
Connections for Surround A and Surround B
Digital Inputs
Signal
Data Shield
Pin
1
Direction
Signal
Shield
Data + (RS-485)
1
To/From Models 790/71
6
To/From Models 790/71
2
To/From Models 790/71
Remote Mute All
5
Input
Data – (RS-485)
Remote Dim
6
Input
Data Shield
Remote Spare 1
8
Input
Remote Spare 2
9
Input
Remote Input Common
4
Common
Note: Connector type on Model 780-02 is 9-pin female
D-subminiature (DE-9F). Connector uses 4-40
threaded inserts for locking with mating plug.
Connections for Remote Control Inputs
Issue 2, April 2015
Page 46
Pin
Direction
DC + (12 V)
4
To Models 790/71
DC – (12 V Return)
9
To Models 790/71
DC Power Shield
5
To/From Models 790/71
Note: Connector type on Model 780-02 is 9-pin female
D-subminiature (DE-9F). Connector uses 4-40
threaded inserts for locking with mating plug.
Connections between Model 780-02 and
Model 790 and Model 71
Model 780-02/790 User Guide
Studio Technologies, Inc.
for Surround
Appendix B—Sync Input Sources
The Model 780-02’s sync input has been tested and confirmed for correct operation with the
following sync signals:
Word Clock: Square wave signal with rate of 44.1, 48, 88.2, or 96 kHz.
DARS (AES11) or AES3: Signal with sample rate of 44.1, 48, 88.2, or 96 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
Model 780-02/790 User Guide
Studio Technologies, Inc.
Issue 2, April 2015
Page 47
for Surround
Appendix C—Downmix Formulas
The following provides a summary of the action performed when the downmix modes are
active. Signals at unity gain unless noted. 0.707 = –3 dB; 0.5 = –6 dB; 0 = full attenuation.
To 5.1
SL = SL + BL
SR = SR + BR
BL and BR mute
To Stereo
L = L + 0.707C + 0.707SL + 0.707BL + (0 or 0.5)LFE
R = R + 0.707C + 0.707SR + 0.707BR + (0 or 0.5)LFE
C, LFE, SL, SR, BL, and BR mute
To Mono
For Surround Input A, Surround Input B
C = .707L + .707R + C + 0.5SL + 0.5SR + 0.5BL + 0.5BR + (0 or 0.5)LFE
L, R, LFE, SL, SR, BL, and BR mute
For Stereo Input
C = 0.707L + 0.707R
L and R mute (LFE, SL, SR, BL, and BR already muted)
Issue 2, April 2015
Page 48
Model 780-02/790 User Guide
Studio Technologies, Inc.
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