Studio Technologies 780-03
for Surround
Model 780-03 Central Controller and
Model 790 Control Console
User Guide
Issue 1, April 2015
This User Guide is applicable for systems consisting of:
Model 780-03: serial number M780-03-00151 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
50394-0415, Issue 1
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for Surround
Table of Contents
Revision History............................................................ 4
Introduction ................................................................... 5
Installation .................................................................... 9
Configuration ................................................................17
Operation ......................................................................36
Technical Notes ............................................................42
Specifications ...............................................................46
Appendix A—Connection Pin-Out Charts ....................48
Appendix B—Sync Input Sources ................................50
Appendix C—Downmix Formulas .................................51
Model 780-03/790 User Guide
Studio Technologies, Inc.
Issue 1, April 2015
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for Surround
Revision History
Issue 1, April 2015:
1. Initial release.
Issue 1, April 2015
Page 4
Model 780-03/790 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
780-03 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
780-03 Central Controller and the Model
790 and Model 71 Control Consoles. With
digital audio inputs, digital and analog
monitor outputs, support for multiple user
control surfaces, and an extensive set of
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, multiple pre- and
post-fader surround outputs, configurable
downmix and mute/solo functions, and
bass management, along with a multi-format sync input, make the system powerful
yet simple to operate. And by using the
best of contemporary technology, as well
as following rigorous design practices, the
system’s audio quality is excellent.
A StudioComm for Surround system starts
with the Model 790 Control Console. It’s
the system’s “command center” and is designed to reside at a user’s location,
Model 780-03/790 User Guide
Studio Technologies, Inc.
allowing fingertip selection of all monitoring
functions. Numerous LEDs provide complete status information. A 4-digit numeric
display indicates the level of the post-fader
digital and analog monitor outputs. 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 780-03 provides power for all connected Model 790 or
Model 71 units.
The core of this StudioComm for Surround system is the Model 780-03 Central Controller. The one-rack-space unit
contains circuitry that supports balanced
digital audio inputs, balanced digital and
analog monitor outputs, digital audio and
control processing, and interfacing for the
user control surface(s). The Model 780-03
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 postproduction 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
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monitored. To compensate with processing
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
780-03’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.
compatible with equipment that requires
balanced AES3 digital audio signals with an
output impedance of 110 ohms and a signal
level of 5 volts peak-to-peak (Vpp).
A sophisticated bass management function is integral to the Model 780-03’s design
and can be enabled if desired. It can apply
to both the post-fader digital and analog
monitor output channels. The overall 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 lowfrequency limitations, preventing a true
sonic “picture” of the source material from
being presented. To overcome this, the lowfrequency 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
outputs. Several of the bass management
functions can be configured to match the
requirements of specific installations.
A range of digital and analog surround
(7.1) monitor outputs are provided. The
post-fader digital and analog monitor outputs are intended for connection to monitor
loudspeaker systems. The pre-fader digital
monitor output can be used with metering systems that require signals that aren’t
impacted by level control or other monitoring functions. The digital monitor outputs are
Figure 1. Model 780-03 Central Controller Front Panel
Control console
status LED
Sync status
LED
Figure 2. Model 780-03 Central Controller Back Panel
AC mains input
To/from
Models 790 &
71 Control
Consoles
Remote control inputs
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Digital
monitor outputs
Sync
input
Stereo
input
Digital surround (7.1)
inputs A & B
Analog monitor outputs
Model 780-03/790 User Guide
Studio Technologies, Inc.
for Surround
Channel mute/solo
Mute/solo
mode
Downmix
Input source
select
Monitor output
level display
Post-fader surround
monitor output
• Surround/stereo
• Reference level
• Mute all
• Dim
• Rotary level control
Figure 3. Model 790 Control Console Front Panel
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.
The Model 780-03 occupies one space
(1U) in a standard 19-inch rack. Digital
audio sources are interfaced with the
Model 780-03 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. Digital and analog monitor output
signal connections are made using two
25-pin female D-subminiature connector.
One 9-pin female D-subminiature connector
is used to connect the Model 780-03 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
Model 780-03/790 User Guide
Studio Technologies, Inc.
control signals. AC mains power is connected directly to the Model 780-03, 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 at a time. It’s
interesting to note that while the surround
inputs have an LFE channel associated
with them, the corresponding post-fader
digital and analog monitor output channels
are 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 subwoofer (SUB) channels of the post-fader digital and analog
monitor outputs.
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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.
The post-fader digital and analog monitor
output levels can be controlled by way of a
large, easy-to-use rotary control. The control, actually a digital encoder, allows level
selection in precise 0.5-dB steps. The auto
mute all function causes the post-fader
digital and analog monitor output channels
to automatically mute whenever the output
level control reaches maximum attenuation. Using the reference level function,
the post-fader digital and analog monitor
output levels can be set to a pre-configured
value. This is provided for audio-with-picture applications that require a specific
monitor output level. The reference level is
easily configured by taking an electronic
“snapshot” of the desired monitor output
level. For user confirmation, the 4-digit LED
display will show the level of the post-fader
digital and analog 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 post-fader
digital and analog monitor output levels
to be reduced by a fixed dB amount. The
dim level is configured from among four
available values. A mute all function allows
the post-fader digital and analog monitor output channels to be simultaneously
muted. The input mute/solo section allows
an input channel to be muted or monitored
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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 post-fader digital and analog monitor outputs to be muted. A second
button allows the subwoofer (SUB) channels of the post-fader digital and analog
monitor outputs 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(s). These
mute and solo resources 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. The downmix functions
always impact the post-fader digital and
analog monitor outputs. A configuration
setting allows the pre-fader digital monitor
output to be selected for pre- or post-downmix operation.
For flexibility, the StudioComm for Surround
system is designed to easily integrate with
equipment such as production intercom
systems, on-air or recording tally signals,
and audio consoles. Two remote-control
Model 780-03/790 User Guide
Studio Technologies, Inc.
for Surround
inputs provide access to the mute all and
dim functions. By providing access to these
functions, talkback or slate activity from an
audio console or other communications
system can control the level of the postfader digital and analog monitor outputs.
Installation
Mounting the Model 780-03
The Model 780-03 Central Controller
requires one space (1U) in a standard
19-inch (48.3 cm) equipment rack. Secure
the Model 780-03 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 780-03 to the Model
790. If the needs of a specific installation
dictate, an alternate-length interconnecting
cable can be fabricated and used.
In this section you will be installing the
Model 780-03 Central Controller in an
equipment rack. Connections to the surround and stereo audio inputs, digital monitor outputs, and analog monitor outputs will
be made. A dedicated digital audio timing
reference signal can be connected to the
sync input. If desired, external equipment
will be interfaced to the remote control inputs. A location will be selected for the first
Model 790 Control Console and it will be
connected to the Model 780-03. AC mains
power will be connected to the Model 78003. For advanced applications up to three
additional Model 790 or Model 71 Control
Console units can be connected to the
Model 780-03.
Audio connections are made by way of
three 25-pin female D-subminiature connectors and one 3-pin female XLR connector. Audio monitor output connections are
made by way of two 25-pin female D-subminiature connector. The connectors are
located on the Model 780-03’s back panel.
Refer to Figure 2 for a detailed view of
these connectors.
System Components
Audio Inputs
The main shipping carton contains one
each of the following: Model 780-03 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.
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 preand post-fader monitor outputs. A one-toone relationship is maintained between the
input and output channels, i.e., left input to
left monitor output, right input to right monitor output, center input to center monitor
output, etc. (Of course this won’t be true in
the case where the user has enabled one
of the three downmix functions.)
Model 780-03/790 User Guide
Studio Technologies, Inc.
Audio Connections
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The audio inputs support digital audio
signals with sample rates of up to 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 780-03’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.
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 780-03 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
The Model 780-03’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.
Note that unlike a TASCAM-type assembly, the two threaded fasteners associated
with the Model 780-03’s D-subminiature
connector use 4-40 threads. This complies
with the original design standard for D-sub
connectors.
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. Often 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.
On the Model 780-03 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.
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Unbalanced AES3 digital audio signals
can also be used with the Model 780-03’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.
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Studio Technologies, Inc.
for Surround
Digital Monitor Outputs
The 25-pin female D-subminiature connector on the back panel labeled Digital
Monitor Outputs provides access to the
Model 780-03’s pre- and post-fader digital
audio monitor outputs. The channels are
organized as two 8-channel surround (7.1)
sources, one pre-fader (fixed level) and the
other post-fader (level adjustable by the
user). The pre-fader digital monitor output
channels are intended for connection to
metering or monitoring equipment that requires uninterrupted full-level signals. The
post-fader digital monitor output channels
are intended to be connected to a loudspeaker system that provides seven main
channels and one subwoofer channel.
The digital monitor outputs are transformer-balanced AES3 digital audio signals
with a source impedance of 110 ohms and
a nominal signal level of 5 Vpp. Signals
of this type are normally interconnected
to destination equipment using shielded
twisted-pair cable terminated with 3-pin
male XLR connectors.
A cable assembly with a 25-pin male
D-subminiature connector (DB-25M) on
one end and the desired connectors on
the other end will be used for connecting
to the digital monitor outputs. The D-subminiature connector follows the TASCAMtype wiring convention, organizing the 25
pins into eight groups of three pins each;
one pin remains unused. Each set of three
pins provides an independent interface.
In the analog world this would allow eight
audio channels to be transported. But with
AES3 digital audio signals this allows support for 16 audio channels; eight interfaces
each supplying two audio channels.
A wiring assembly prepared for the Model
780-03’s digital monitor outputs would typically be identical to that of a TASCAM-type
output assembly. An assembly of this type
would often have a 25-pin male D-subminiature connector (DB-25M) on one end and
eight 3-pin male XLR connectors on the
other.
For compatibility with balanced AES3
digital audio signals connect the D-sub’s
+ terminal as signal high and the – terminal
as signal low. In most applications a 3-pin
male XLR connector will be used. In this
case the + terminal would go to pin 2 of
the XLR, the – terminal to XLR pin 3, and
the shield terminal to XLR pin 1. Refer to
Figure 5 or Appendix A for the exact connection details. Note that unlike a TASCAMtype assembly, the two threaded fasteners
associated with the Model 780-03’s D-sub
connectors use 4-40 threads. This complies
with the original design standard for Dsubminiature connectors.
Connections
Channel
Signal
High (+)
Signal
Low (–)
Shield
Pre-Fader L/R
1
24
12
25
Pre-Fader C/SUB
2
10
23
11
Pre-Fader SL/SR
3
21
9
22
Pre-Fader BL/BR
4
7
20
8
Post-Fader L/R
5
18
6
19
Post-Fader C/SUB
6
4
17
5
Post-Fader SL/SR
7
15
3
16
Post-Fader BL/BR
8
1
14
2
Notes: 1) All signals transformer-coupled digital audio;
balanced AES3 (110 ohms, 5 Vpp) compatible.
2) Connector type on Model 780-03 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 5. Connections for Digital Monitor Outputs
Model 780-03/790 User Guide
Studio Technologies, Inc.
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Pre-Fader Monitor Output
The pre-fader digital monitor output channels are intended to connect to metering,
measurement, or other signal monitoring
equipment that requires uninterrupted, fulllevel digital audio signal sources.
Post-Fader Monitor Output
The post-fader digital monitor output channels are designed for connection to digital
inputs on audio amplifiers associated with
monitor loudspeakers. Alternately, they can
be connected to the inputs of loudspeakers
that contain integrated amplifiers with digital
audio input capability.
Analog Monitor Outputs
The 25-pin female D-subminiature connector on the back panel labeled Analog Monitor Outputs provides access to the Model
780-03’s post-fader analog surround (7.1)
monitor output. The eight output channels
are intended for connection with the inputs
on a loudspeaker system that provides
seven main channels and one subwoofer
channel.
The analog monitor output channels are
designed for connection to audio amplifiers
associated with monitor loudspeakers, or
to the inputs of loudspeakers that contain
integrated amplifiers. The analog monitor
outputs are electronically balanced and
will perform optimally when driving loads
of 2000 (2 k) ohms or greater. In most applications 3-pin 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.
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Balanced operation of the post-fader analog monitor outputs is the preferred connection method but unbalanced operation
does not pose a problem. To connect to an
unbalanced load connect the + terminal as
signal high, and only the Model 780-03’s
shield terminal as the signal low/shield.
Leave the – terminal unconnected. For correct unbalanced operation, it is important
not to connect – and shield together.
The wiring scheme used by the D-subminiature connector complies with AES592012, as made popular by TASCAM. A
wiring assembly prepared for the Model
780-03’s analog monitor outputs is identical to that of a TASCAM-type output assembly. Please refer to Figure 6 for the
exact connection details. Again note that
unlike a TASCAM-type assembly, the
Model 780-03’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 780-03 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 6. Connections for Analog Monitor
Outputs
Model 780-03/790 User Guide
Studio Technologies, Inc.
for Surround
Sync Input
The Model 780-03 requires a timing reference (sync) source so that the digital audio
input and digital monitor output signals
will be handled correctly. A configuration
setting allows the source of sync to be
selected. The default setting uses the L/R
input of the currently selected digital 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 780-03’s sync input connector.
The connected sync source must maintain
a stable relationship between itself and the
digital audio inputs. The actual sync source
can be in one of several formats: word
clock, DARS (AES11), bi-level video, or
tri-level video.
An overview of the various compatible
timing reference signals might prove
worthwhile. Word clock is a digital signal
that is locked in phase and frequency to
the sample rate of the associated digital
audio sources. DARS (digital audio reference source) is a timing signal compliant
with the AES11 standard. It’s sometimes
referred to as “AES3-black.” Technically it is
similar to an AES3 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 780-03
supports both bi-level and tri-level signals
Model 780-03/790 User Guide
Studio Technologies, Inc.
at numerous rate combinations, allowing
for compatibility with various worldwide
video formats.
With the wide range of allowable sync
sources proper Model 780-03 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 780-03’s back
panel. For flexibility the Model 780-03’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 780-03’s
sync input would typically want to have
the input termination enabled. If the sync
signal connected to the Model 780-03 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. These functions only impact
the post-fader digital and analog monitor outputs. The Model 780-03’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
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should be taken to prevent nasty signals
from reaching them. The inputs are active
only when held in the low state; they can’t
be configured to change state (“latch”) in
response to a logic pulse.
A 9-pin D-subminiature connector (DE-9F)
is used for the remote control inputs. Refer
to Figure 7 or Appendix A for connection
details. Note that pin 4 (remote common)
connects to the Model 780-03’s internal
circuit common connection as well as to
the Model 780-03’s chassis and mains
earth connections. Figure 7 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 780-03 is 9-pin female
D-subminiature (DE-9F). Connector uses 4-40
threaded inserts for locking with mating plug.
Figure 7. Connections for Remote Control
Inputs
Connecting the Model 780-03
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 780-03 Central Controller. This is
used to interface the unit with Model 790
Control Consoles. Refer to Figure 8 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
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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 780-03 is 9-pin female
D-subminiature (DE-9F). Connector uses 4-40
threaded inserts for locking with mating plug.
Figure 8. Connections between Model 780-03
and Model 790 and Model 71
with 9-pin male D-sub (DE-9M) connectors
on each end is used to interconnect the
Model 780-03 with the Model 790 units. A
cable, approximately 20 feet
(6 meters) in length, is included in the shipping carton. The cable implements all nine
connector pins in a one-to-one manner.
Should an interconnecting cable of a different length be required there’s no problem
for one to be fabricated and used. While
it can be wired in a one-to-one fashion
supporting all nine pins, only four connections are actually required: pin 1 (data +),
pin 6 (data –), pin 4 (DC +), and pin 9 (DC
–). The Model 780-03’s connector pin-out
scheme was designed to allow creation of
an interconnecting cable which uses commonly available 2-pair audio cable. This
cable, consisting of two twisted pairs each
with an individual shield, is typically 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.
Model 780-03/790 User Guide
Studio Technologies, Inc.
for Surround
A few simple calculations are required to
determine the maximum cable length when
fabricating a cable to be used when connecting a Model 780-03 to a Model 790.
The differential transmission scheme used
by the system’s RS-485 interface makes
an interconnection in excess of 1000 feet
(>300 meters) easily possible. The limiting
factor is typically the ability of the wiring to
pass the DC power supplied by the Model
780-03 to a Model 790. The Model 780-03
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 780-03 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 780-03’s ability to be controlled by
additional control consoles. At least one
Model 780-03/790 User Guide
Studio Technologies, Inc.
Model 790 Control Console must be connected to the Model 780-03 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 780-03.
When connecting multiple control consoles
to a Model 780-03 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 780-03 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 780-03 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
Issue 1, April 2015
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for Surround
jumpers to install to match a location’s AC
mains voltage. The unit uses a 3-pin IEC
320 C14-type inlet connector to mate with
a detachable AC mains cord. All units are
supplied with an AC mains cord that has
a North-American-standard plug (NEMA
5-15L) on one end and an IEC 320 C13
socket on the other. Units bound for other
destinations 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 780-03
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 AC mains power is applied
the Model 780-03 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 780-03’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
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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 AC mains power,
all connected Model 790 units will go
through a power-up sequence, lighting
each of its LEDs in succession. Using its
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
780-03.
All connected Model 71 units will also go
through a power-up sequence after AC
mains power is applied to the Model 78003. 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 9 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 780-03. 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 780-03’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.
Only after the Model 780-03 and all connected Model 790 and Model 71 units have
correctly powered up will full system operation begin.
Model 780-03/790 User Guide
Studio Technologies, Inc.
for Surround
Configuration
After the physical installation has been
completed it’s important that the system’s
configuration options be carefully reviewed.
In most cases one or more of the operating parameters will be revised to meet the
needs of the specific installation. Many of
the configuration parameters will impact
the signal flow in to and out of the Model
780-03 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
• Overall Display Mode
• Reference Level in dB SPL
• Auto Reference Level Off
• Dim Level
Model 780-03/790 User Guide
Studio Technologies, Inc.
• Remote Inputs
• LFE Downmix Level
• Pre-Fader Digital Monitor Output Mode
• Input Delay Settings
• Post-Fader Digital and Analog Monitor
Output Channel Level Offsets
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 780-03 into their configuration modes. Other connected Model
790 and Model 71 units will enter a standby
mode. When the Model 780-03 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.
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for Surround
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 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 780-03 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 780-03.
Model 790 Device Address
A unique device address must be assigned
to each Model 790 Control Console that is
connected to a Model 780-03. 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
Issue 1, April 2015
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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
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
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 780-03,
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.
Bass Management
The Model 780-03 incorporates flexible
and sonically excellent bass management
capabilities which can impact both the
Model 780-03/790 User Guide
Studio Technologies, Inc.
for Surround
post-fader digital and analog monitor outputs. 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 performance of
the associated loudspeaker system can a
plan for the bass management functions
be selected.
The bass management function impacts
only the post-fader digital and analog
monitor outputs 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 highpass 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 dB-per-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.
Sync Source
The Model 780-03 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 digital surround or stereo input
to also serve as the system’s sync source.
This fourth choice is the default value.
Model 780-03/790 User Guide
Studio Technologies, Inc.
Sync Input Termination
The sync input circuitry can be configured
to provide a termination impedance of 75
ohms 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 780-03’s BNC
input connector then enabling termination
is typically appropriate. However, if the
sync source is being “shared” by multiple
inputs then care must be taken so that the
signal is only terminated by one device. 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 780-03’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
digital audio sources.
Reference Level
For consistent monitoring of audio signals
it’s often beneficial for users to be able to
easily set the post-fader digital and analog
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 post-fader
digital and analog monitor output level to
be stored and then enabled by pressing
the Model 790 button labeled Reference
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for Surround
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.
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 all the monitor output channels
(digital and analog) 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.
Issue 1, April 2015
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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 780-03’s nonvolatile
memory. Only by repeating the entire
procedure can the value be changed.
Once the configuration mode has been
exited, the monitor digital and analog monitor outputs will again become active. Confirm that the correct level has been stored
by pressing the reference level button. The
SPL meter should display the desired level.
If not, repeat the calibration procedure to
achieve the desired goal.
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 post-fader
digital and analog 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 post-fader monitor outputs.
Model 780-03/790 User Guide
Studio Technologies, Inc.
for Surround
In the SPL mode the display can be configured to allow the post-fader 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.
Reference Level in dB SPL
The reference level in dB SPL configuration allows a specific SPL value to be
associated with the stored reference level
value. In this way whenever the post-fader
digital and analog monitor outputs are at
their reference level, either through activating the reference level function or manually
adjusting the rotary level control, the Model
790’s display will show the configured
SPL level. Whenever the post-fader digital
and analog monitor outputs are not at the
reference value the display will show the
current value, in dB, relative to the reference level. The reference level in dB SPL
can be configured over a range of 70.0 to
100.0 dB in 1.0-dB steps. In many applications 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.
Model 780-03/790 User Guide
Studio Technologies, Inc.
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
post-fader digital and analog monitor output
levels by a preset amount. The reduction is
in dB relative to the post-fader 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.
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
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for Surround
Stereo downmix function is active, LFE is
reduced in level by 6 dB and routed to both
the left (L) and right (R) post-fader digital
and analog monitor outputs. 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)
channel of the post-fader digital and analog
monitor outputs.
Pre-Fader Digital Monitor
Output Mode
The pre-fader digital monitor output can
be configured as to its place in the Model
780-03’s signal flow. The choices are pre- or
post-downmix. In the pre-downmix mode
the pre-fader digital monitor output channels will not be impacted by the state of the
three downmix functions. This setting would
be appropriate if the pre-fader digital monitor outputs were being routed to a storage
system, routed to another facility, etc. In this
case the action of a user enabling or disabling the downmix functions won’t impact
the level of the pre-fader digital monitor
output channels. If the post-downmix mode
is selected the pre-fader digital monitor
outputs will reflect the actions of the downmix functions. This choice would be correct
if, for example, level meters were connected
to the pre-fader digital monitor outputs. In
this scenario a user would want to visually
observe the actions that the downmix functions impart on the signals. By default the
pre-fader digital monitor outputs are configured to be pre-downmix.
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
Issue 1, April 2015
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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.
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.
Post-Fader Digital and Analog
Monitor Output Level Offsets
To provide assistance during room calibration, the relative output levels of the postfader digital and analog 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
Model 780-03/790 User Guide
Studio Technologies, Inc.
for Surround
cases one channel should serve as the
overall reference level and not be changed.
This is typically the center channel.
This feature is provided primarily for use
when the post-fader 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 post-fader monitor output levels 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.
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 780-03 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 9
for details.
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!
Model 780-03/790 User Guide
Studio Technologies, Inc.
Figure 9. Model 71 Control Console Front and
Back Panels
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for Surround
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 10 for details.
Address
Dim LED
Reference Level LED
A1
OFF
OFF
A2
OFF
ON
A3
ON
OFF
A4
ON
ON
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 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 10. Model 71 Device Address Chart
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Configuration—Entering and Exiting Configuration Mode
and hold the configuration
 Press
button for 2 seconds to enter or
exit the configuration mode.
These LEDs will light alternately
when configuration mode is active.
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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 780-03.
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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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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 post-fader monitor output level.
Note:
The 5-second button-press delay is a safety feature ensuring that the reference level will not be accidently
changed. To permanently store the new value, you must still exit the configuration mode.
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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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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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Configuration—LFE Downmix Level and Pre-Fader Monitor
Output Mode
These LEDs display the configuration of the prefader monitor output mode. LED L lit means output
channels are pre-downmix; LED R lit means output
channels are post-downmix. Use the buttons to
change the configuration.

Default:
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.
Press and hold the To Mono button to display and confirm
the LFE downmix level and pre-fader monitor output mode.
LFE downmix level full attenuation when To Stereo or To Mono downmix functions active.
Pre-fader monitor outputs pre-downmix.
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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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Configuration—Post-Fader 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 post-fader
monitor output level offsets. The range is
–12.0 to 12.0 in 0.5-dB steps.
Default:
0.0 dB post-fader monitor output level offsets.
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Configuration—Restore Factory Defaults
and hold both the LFE Low-Pass and Dim buttons for 5 seconds to
 Press
restore Model 780-03 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 post-fader monitor
output level.
Attenuation display mode selected.
85.0 dB SPL reference level.
Auto reference level off disabled.
–20 dB dim level.
Remote mute all enabled.
Remote dim enabled.
LFE downmix level full attenuation when To Stereo or
To Mono downmix functions active.
Pre-fader monitor outputs pre-downmix.
Input delay 0 milliseconds for both A and B.
0.0 dB post-fader 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.
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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 modes,
etc. As a precaution, however, the post-fader digital and analog monitor output levels
will always return to the minimum value. The
rotary level control or the reference level
button must then be used to return the system to the desired monitor output level.
Model 780-03 Central
Controller
The Model 780-03’s front panel contains
two LEDs. The control console status LED
will light whenever the Model 780-03 is
communicating with the one or more connected Model 790 or Model 71 units. A
flashing control console status LED will
indicate that the 12 Vdc output provided to
support the connected control consoles is
in a 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 780-03. 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 a
Model 780-03/790 User Guide
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for Surround
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.
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 is –60.0 dB so “out
of the box” the Model 790 will display –60.0
when reference level mode is enabled.
Using the downmix functions simply requires pressing the desired button. The
buttons are set to always “latch” the functions on and off. An LED, located adjacent to each button, will light whenever its
respective function is active. The downmix
functions always impact the post-fader
monitor output. And, depending on the
selected configuration, may also impact
the pre-fader digital monitor output. For
details on the exact actions performed
by the three downmix functions refer to
Appendix C at the end of this user guide.
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.
Monitor Output General
Functions
Four buttons and one rotary control are
associated with the post-fader digital and
analog monitor outputs. 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 post-fader
digital and analog monitor output levels.
Reference Level
The reference level button sets the postfader digital and analog monitor output levels to a preset value. Technical personnel,
using a sound-pressure-level (SPL) meter
and precision signal source, should have
set this level to meet the requirements of
Model 780-03/790 User Guide
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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
output channels associated with the digital
and analog monitor outputs to mute. The
4-digit display indicates the mute condition by showing four dashes (– – – –). The
mute all button is always set to “latch” the
function on and off. The LED associated
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with the mute all button will light whenever
mute all is active. Note that if mute all is
enabled via the remote mute all function,
the mute all LED will flash.
Dim
The dim function is provided for user convenience, allowing the post-fader digital
and analog 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 post-fader monitor output level.
When dim is active the post-fader monitor
output level reduction will apply no matter
whether the level is being set by the rotary level control or by the reference level
button. The LED associated with the dim
button will light whenever dim is active. If
dim mode is enabled via the remote dim
function the dim LED will flash.
It’s worth using a few sentences to discuss
the auto dim off function. Whenever dim
is enabled due to the dim button being
pressed, and the rotary level control is
active (reference level mode is not active),
changing the setting of the rotary level
control will automatically turn off dim. The
auto dim off function is a unique attempt
at protecting the aural health of users. No
longer will there be a heart-stopping blast
of audio when the dim button is pressed,
supposedly to enable dim, but actually
turning dim off because it was already
enabled. It’s hard to explain unless you’ve
experienced this in person—trust us, this
situation can and does happen!
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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.
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.
Model 780-03/790 User Guide
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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 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 post-fader digital and analog
monitor output levels. The level control
provides the ability to adjust the post-fader
digital and analog monitor output level over
a 70-dB range. Technically, the rotary level
control is a 24-step-per-revolution mechanical encoder. The amount of level change
in dB per step (per “click”) will depend on
how quickly the control is turned. When
rotated slowly, each step represents a 0.5dB change in level. In this case, to traverse
the entire level range would require rotating the control more than five full turns. But
the Model 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 post-fader monitor
output channels will automatically mute.
As previously discussed, the 4-digit display
indicates the mute condition by showing
four dashes (– – – –).
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If the mute all function is active the rotary
level control won’t have an impact on the
post-fader 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.
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
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muting the post-fader digital and analog
monitor output channels. These serve as
an aid in observing the performance of the
associated 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 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
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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
which the Model 780-03 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 11 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 post-fader digital and analog monitor
output levels as either the amount of attenuation or the sound pressure level (SPL).
Both will indicate level in dB. What the digits actually represent will depend upon how
the Model 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 0.5dB steps less than the maximum of 0.0 dB.
So a display of –40.5 would indicate that
the post-fader digital and analog monitor output is set to be 40.5 dB below the
maximum level. As the rotary level control
is moved counterclockwise the output level
will go down and the indicated value will
get more negative.
Model 780-03/790 User Guide
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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 11. Selecting the input delay
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
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.
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Remote Control Inputs
As previously discussed in the Installation section of this user guide, two remote
control signals can be connected to the
Model 780-03. 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
activated, the LED will change from being
steadily lit to flashing.
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.
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Model 71 Control Console
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 post-fader digital and analog 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.
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 post-fader digital and analog
monitor output levels. 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 post-fader
digital and analog monitor output level to
be reduced by a fixed amount. Its operating characteristics are identical to those of
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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 postfader digital and analog monitor output
level to the preset value. The 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 780-03 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 780-03’s back panel.
Alternately, a configuration choice allows
the L/R input of the currently selected
digital input source to also serve as the
system’s timing reference. Whenever a
valid sync signal has been connected to
Model 780-03/790 User Guide
Studio Technologies, Inc.
for Surround
the Model 780-03 the sync status LED, located on the unit’s front panel, will light. The
sample rate of the pre- and post-fader digital
monitor output channels will reflect the rate
of the sync input and, if a video sync source
is utilized, the configured rate.
If a valid sync signal is not present several
visual indications are provided. On the Model 780-03 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 780-03’s
sync status LED will light steadily. On the
Model 790 units the 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 780-03’s configuration.
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.
Any time that a valid sync signal is not connected to the Model 780-03 the pre- and
post-fader digital monitor outputs will automatically revert to an internally generated
sample rate of 48 kHz with no digital audio
content present. This audio “black” signal will
allow most connected equipment to continue to function correctly with, of course, no
meaningful audio signal present. As soon as
a valid sync signal is again connected to the
Model 780-03 the pre- and post-fader digital
monitor outputs will automatically switch to
their correct sample rate and audio signals
will again be present.
Model 780-03/790 User Guide
Studio Technologies, Inc.
Power Down
Great care was taken in the Model 780-03’s
design to minimize the chance that clicks,
pops, or other objectionable audio signals
will be present on the post-fader digital
and analog monitor outputs. A power-down
circuit supplies the main microcontroller
integrated circuit with an indication that a
power loss is imminent. When this condition is detected the digital monitor outputs
will switch to silence (digital audio “black”)
in preparation for a complete loss of signal.
Electromechanical relays associated with
the analog monitor outputs will change to
their mute state to minimize the chance of
signal transients reaching the connected
loudspeaker inputs.
Power-Up Messages
Upon AC mains power being applied to
the Model 780-03 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 780-03 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
5. Displays Model 780-03’s main software
version
6. Displays FPgA
7. Displays Model 780-03’s logic device
(FPGA) software version
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After a successful system power-up
sequence normal operation will then
commence.
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 780-03.
The most likely cause would be incorrect wiring of the data pair linking the two
units. Err2 indicates that the Model 780-03
is having problems with its internal logic
device. (A high-speed field-programmable
gate array (FPGA) serves as the digital
“heart” of the Model 780-03 and without it
no audio activity can occur.) The only way
to remedy this condition is to first try removing and reconnecting AC mains power.
(And that’s a long-shot as to whether it
would accomplish anything.) If Err2 continues to be displayed the Model 780-03 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.
Sample Rate Conversion
(SRC)
Circuitry associated with the stereo input
can provide sample rate conversion (SRC)
Issue 1, April 2015
Page 44
capability. A digital audio signal connected
to that input can have its sample rate and
timing re-synchronized to match the Model
780-03’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 780-03.
The technical capabilities of the Model
780-03’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
780-03’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 780-03’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 78003’s output sample rate. If a video sync
signal is connected, the Model 780-03’s
sample rate is selected as part of the configuration process.
So in practice what can the SRC function
accomplish? If the monitor output 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 780-03’s monitor output sample
rate is 96 kHz a signal connected to the
stereo input can have its sample rate
range from 16 to 216 kHz.
As useful as allowing one sample rate to
be converted to another, it may be the ability of the Model 780-03’s SRC function to
re-synchronize a signal that proves most
valuable. For example, in typical postproduction and broadcast applications all
Model 780-03/790 User Guide
Studio Technologies, Inc.
for Surround
signals will have a sample rate of 48 kHz.
A Model 780-03 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 780-03’s rate, thus
allowing it to be monitored over
a loudspeaker system.
Model 780-03 to Control
Console Connections
Figure 8 gives a detailed description of
the signals that connect the Model 780-03
Central Controller to the one or more Model
790 or Model 71 Control Consoles. The
Model 780-03 provides 12 Vdc for use by
the control console’s circuitry. The DC output is current-limited to 100 mA to minimize
the chance that a short-circuit condition
will damage the Model 780-03’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 780-03 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.
reconnect without issue. Upon disconnection of all control consoles the Model
780-03 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.
Channel Status, User, and
Validity Bits
The non-audio bits that are part of the
AES3 digital audio monitor output channel
data are actively controlled by the Model
780-03’s software. The Channel Status
bits use the Professional Use of Channel
Status block. They indicate a word length
of 24 and the current sample rate. The correct CRC is also calculated and inserted.
The User bits are always set to 0. When
a valid timing reference (sync) source is
recognized by the system the Validity bits
will be set to 1.
The Model 780-03’s hardware is capable
of routing the C/U/V bit information from
any of the L/R inputs, as well as the sync
input, to the main logic device (FPGA)
and then on to the digital audio transmitter
(DIT) integrated circuits. This is provided
for future use and is not active at this time.
“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
Model 780-03/790 User Guide
Studio Technologies, Inc.
Issue 1, April 2015
Page 45
for Surround
Specifications
Model 780-03 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
Latency: 1 millisecond, nominal
LFE Input Channel Low-Pass Filter: –6 dB @
120 Hz, 48 dB-per-octave, on/off selectable
Sync Source: configured to follow L/R of currently
selected input or signal connected to sync input
Sync Input:
Compatible Sources: word clock, DARS (AES11),
bi-level video, tri-level video
Jitter: 4 ns pp maximum
Connector: BNC (per IEC 60169-8 Amendment 2)
Termination: 75 ohms, selectable on/off
Digital Monitor Outputs: 16 channels (8 pairs)
Configuration: organized as two surround (7.1),
one pre-fader, and one post-fader
Dynamic Range: >135 dB
Type: balanced AES3 (110 ohms, 5 Vpp)
Connector: 25-pin female D-subminiature
(DB-25F), AES59-2012-compliant
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Analog Monitor Outputs: 8
Configuration: organized as one surround (7.1),
post-fader
Type: electronically balanced, source impedance
200 ohms
Nominal Level: +4 dBu @ –20 dBFS input source
and level control at maximum setting
Maximum Level: +24 dBu into 2000 (2 k) ohms or
greater
Frequency Response, Digital Inputs to Analog
Monitor Outputs: 10 Hz-20 kHz +0.0/–0.3 dB @
48 kHz sample rate; –3 dB @ 64 kHz
Distortion (THD+N): 0.004%, ref 1 kHz, +4 dBu
output
S/N Ratio: 89 dB, ref +4 dBu output
Dynamic Range: >109 dB
Crosstalk: –98 dB at 1 kHz; –97 dB at 16 kHz,
ref –1 dBFS input
Connector: 25-pin female D-subminiature
(DB-25F), AES59-2012-compliant
Configurable Input Delay: 0 to 340 milliseconds
@ 48 kHz sample rate (scales up or down depending on actual sample rate)
Post-Fader Monitor Output Level Offsets: each
surround (7.1) channel independently adjustable
in 0.5-dB steps over a ±12-dB range. (Digital and
analog outputs associated with a specific channel
share the same setting.)
Bass Management:
Crossover Frequency and Type: –6 dB @ 40, 50,
60, or 80 Hz, symmetrical for low-pass and highpass 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
Control Console Interface:
Type: RS-485, 115.2 kbit/s, 8-1-N
Polling Interval: 80 milliseconds, nominal
Power: 12 Vdc, 500 mA maximum
Connector: 9-pin female D-subminiature (DE-9F)
Model 780-03/790 User Guide
Studio Technologies, Inc.
for Surround
Remote Control Inputs: 2
Functions: remote mute all, remote dim
Type: 3.3 Vdc logic, activates on closure to system
common
Connector: 9-pin female D-subminiature (DE-9F)
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)
Dimensions:
19.00 inches wide (48.3 cm)
1.72 inches high (4.4 cm)
7.00 inches deep (17.8 cm)
Mounting: one space (1U) in a standard 19-inch
rack
Model 71 Control Console
Application: up to three Model 71 Control Consoles can be connected to a Model 780-03 Central
Controller
Power: 12 Vdc nominal (9 Vdc minimum), maximum current 35 mA, provided by Model 780-03
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)
Weight: 3.6 pounds (1.6 kg)
Model 790 Control Console
Specifications and information contained in this
User Guide subject to change without notice.
Application: up to four Model 790 Control Consoles can be connected to a Model 780-03 Central
Controller
Power: 12 Vdc nominal (9 Vdc minimum), maximum current 100 mA, provided by Model 780-03
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 780-03/790 User Guide
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Issue 1, April 2015
Page 47
for Surround
Appendix A—Connection Pin-Out
Charts
Channel
Signal
High (+)
Signal
Low (–)
Shield
Connections
Channel
Signal
High (+)
Signal
Low (–)
Shield
Surround Input A L/R
1
24
12
25
Pre-Fader L/R
1
24
12
25
Surround Input A C/LFE
2
10
23
11
Pre-Fader C/SUB
2
10
23
11
Surround Input A SL/SR
3
21
9
22
Pre-Fader SL/SR
3
21
9
22
Surround Input A BL/BR
4
7
20
8
Pre-Fader BL/BR
4
7
20
8
Surround Input B L/R
5
18
6
19
Post-Fader L/R
5
18
6
19
Surround Input B C/LFE
6
4
17
5
Post-Fader C/SUB
6
4
17
5
Surround Input B SL/SR
7
15
3
16
Post-Fader SL/SR
7
15
3
16
Surround Input B BL/BR
8
1
14
2
Post-Fader BL/BR
8
1
14
2
Connections
Notes: 1) All signals transformer-coupled digital audio;
balanced AES3 (110 ohms, 5 Vpp) compatible.
Notes: 1) All signals transformer-coupled digital audio;
balanced AES3 (110 ohms, 5 Vpp) compatible.
2) Connector type on Model 780-03 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) Connector type on Model 780-03 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.
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 for Surround A and Surround B
Digital Inputs
Signal
Pin
Direction
Connections for Digital Monitor Outputs
Channel
Signal
High (+)
Signal
Low (–)
Shield
Left (L)
1
24
12
25
Right (R)
2
10
23
11
22
Connections
Data Shield
1
Shield
Remote Mute All
5
Input
Center (C)
3
21
9
Remote Dim
6
Input
Subwoofer (SUB)
4
7
20
8
Remote Spare 1
8
Input
Surround Left (SL)
5
18
6
19
Remote Spare 2
9
Input
Surround Right (SR)
6
4
17
5
Remote Input Common
4
Common
Back Left (BL)
7
15
3
16
Back Right (BR)
8
1
14
2
Note: Connector type on Model 780-03 is 9-pin female
D-subminiature (DE-9F). Connector uses 4-40
threaded inserts for locking with mating plug.
Connections for Remote Control Inputs
Notes: 1) Connector type on Model 780-03 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
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Model 780-03/790 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 780-03 is 9-pin female
D-subminiature (DE-9F). Connector uses 4-40
threaded inserts for locking with mating plug.
Connections between Model 780-03 and
Model 790 and Model 71
Model 780-03/790 User Guide
Studio Technologies, Inc.
Issue 1, April 2015
Page 49
for Surround
Appendix B—Sync Input Sources
The Model 780-03’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
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Model 780-03/790 User Guide
Studio Technologies, Inc.
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)
Model 780-03/790 User Guide
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Issue 1, April 2015
Page 51
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