for Surround Model 780-01 Central Controller and Model 790 Control Console User Guide

for Surround Model 780-01 Central Controller and Model 790 Control Console User Guide
for Surround
Model 780-01 Central Controller and
Model 790 Control Console
User Guide
Issue 2, April 2015
This User Guide is applicable for systems consisting of:
Model 780-01: serial number M780-01-00151 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
50390-0415, Issue 2
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for Surround
Table of Contents
Revision History............................................................ 4
Introduction ................................................................... 5
Installation .................................................................... 9
Configuration ................................................................16
Operation ......................................................................35
Technical Notes ............................................................41
Specifications ...............................................................45
Appendix A—Connection Pin-Out Charts ....................47
Appendix B—Sync Input Sources ................................48
Appendix C—Downmix Formulas .................................49
Model 780-01/790 User Guide
Studio Technologies, Inc.
Issue 2, April 2015
Page 3
for Surround
Revision History
Issue 2, April 2015:
1. Revised specifications to reflect final audio performance measurements.
2. Text clarifications.
Issue 1, January 2015:
1. Initial release.
Issue 2, April 2015
Page 4
Model 780-01/790 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
780-01 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 780-01
Central Controller and the Model 790 and
Model 71 Control Consoles. With digital
audio inputs, digital 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, 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 780-01/790 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
monitor output. A major strength of the
Model 790 is its ability to configure, under
software control, many important operating parameters. Intended for secondary
monitoring locations that don’t require all
of the Model 790’s features, the Model 71
Control Console is a compact user control
surface. It provides three of the most basic
functions: a rotary level control, dim on/off
button, and reference level on/off button.
Most installations will use only one Model
790 Control Console. However, up to three
additional Model 790 or Model 71 Control
Consoles can also be connected. This
provides multiple users with control over
a facility’s monitor system. And to make
installation simple, the Model 780-01 provides power for all connected Model 790 or
Model 71 units.
The core of this StudioComm for Surround
system is the Model 780-01 Central Controller. The one-rack-space unit contains
circuitry that supports balanced digital
audio inputs, balanced digital monitor
outputs, digital audio and control processing, and interfacing for the user control
surface(s). The Model 780-01 provides two
surround (7.1) and one stereo digital audio
inputs. These balanced digital inputs are
AES3-compliant; sources of this type are
ubiquitous in many post-production and
audio facility environments. The inputs
allow a sample rate of 44.1, 48, 88.2 or
96 kHz and a bit depth of up to 24 to
be supported. Circuitry associated with
the stereo input provides sample rate
conversion (SRC) capability, allowing a
wide range of digital audio sources to be
monitored. To compensate with processing
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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 780-01’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.
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 780-01’s design
and can be enabled if desired. 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 low-frequency limitations, preventing a
true sonic “picture” of the source material
from being presented. To overcome this,
the low-frequency energy from the seven
channels associated with the surround
inputs and the two channels associated
with the stereo input can be separated and
routed to the subwoofer (SUB) channel of
the post-fader monitor output. Several of
the bass management functions can be
configured to match the requirements of
specific installations.
Two surround (7.1) digital monitor outputs
are provided. The pre-fader monitor output
can be used with metering systems that
require signals that aren’t impacted by
level control or other monitoring functions.
The post-fader monitor output is intended
for connection to the inputs on a monitor
loudspeaker system. Both the pre- and
post-fader monitor outputs are compatible with equipment that requires balanced
Figure 1. Model 780-01 Central Controller Front Panel
Control console
status LED
Sync status
LED
Figure 2. Model 780-01 Central Controller Back Panel
AC mains input
To/from
Models 790 &
71 Control
Consoles
Digital
monitor outputs
Sync
input
Stereo
input
Digital surround (7.1)
inputs A & B
Remote control inputs
Issue 2, April 2015
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Model 780-01/790 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 780-01 occupies one space
(1U) in a standard 19-inch rack. Digital
audio sources are interfaced with the Model
780-01 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. Preand post-fader digital monitor output signal
connections are made using a 25-pin female D-subminiature connector. One 9-pin
female D-subminiature connector is used to
connect the Model 780-01 with a maximum
of four Model 790 or Model 71 Control Consoles. A second 9-pin “D-sub” connector
is used to interface with remote control
Model 780-01/790 User Guide
Studio Technologies, Inc.
signals. AC mains power is connected
directly to the Model 780-01, 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 monitor output channel is designated as subwoofer (SUB), rather than
LFE. This terminology was selected to
highlight the fact that this output channel
may include more than just LFE content.
The bass management function, if enabled, will redirect low-frequency energy
from the main channels, combine it with
the contents from the LFE input channel,
and route the combination to the postfader monitor output’s subwoofer (SUB)
channel.
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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 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 monitor output channels to automatically mute whenever the
output level control reaches maximum attenuation. Using the reference level function, the post-fader 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 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
monitor output level to be reduced by a
fixed dB amount. The dim level is configured from among four available values.
A mute all function allows the post-fader
monitor output channels to be simultaneously muted. The input mute/solo section
allows an input channel to be muted or
monitored as desired. Multiple channels
can also be simultaneously selected for
muting or “soloing.”
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Two output mute functions are also provided. One button allows the seven main
channels of the post-fader monitor output
to be muted. A second button allows the
subwoofer (SUB) channel of the post-fader
monitor output to be muted. The output
mute functions, along with the input mute/
solo function, allow a user complete flexibility when checking an input source and
its path to the loudspeaker system. These
mute and solo resources 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 monitor output.
A configuration setting allows the pre-fader
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
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 monitor outputs.
Model 780-01/790 User Guide
Studio Technologies, Inc.
for Surround
Installation
In this section you will be installing the
Model 780-01 Central Controller in an
equipment rack. Connections to the surround and stereo audio inputs and preand post-fader surround 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 780-01. AC
mains power will be connected to the Model
780-01.
For advanced applications up to three
additional Model 790 or Model 71 Control
Console units can be connected to the
Model 780-01.
System Components
The main shipping carton contains one
each of the following: Model 780-01
Central Controller, Model 790 Control Console, 9-pin D-subminiature interconnecting
cable (approximately 20 feet (6 meters) in
length), and a user guide. Also included
in the shipping carton is a North-American-standard AC mains cord. Your dealer
or distributor should provide an AC mains
cord appropriate for destinations outside of
North America. Any additional Model 790 or
Model 71 Control Consoles will be shipped
in separate cartons.
Mounting the Model 780-01
The Model 780-01 Central Controller
requires one space (1U) in a standard
19-inch (48.3 cm) equipment rack. Secure
the Model 780-01 into the equipment rack
using two mounting screws per side. Select
Model 780-01/790 User Guide
Studio Technologies, Inc.
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 780-01 to the Model
790. If the needs of a specific installation
dictate, an alternate-length interconnecting
cable can be fabricated and used.
Audio Connections
Audio input connections are made by way
of one 25-pin female D-subminiature connector and one 3-pin female XLR connector. Audio monitor output connections are
made by way of one 25-pin female D-subminiature connector. The connectors are
located on the Model 780-01’s back panel.
Refer to Figure 2 for a detailed view of
these connectors.
Audio Inputs
Two balanced digital surround (7.1) and
one balanced digital stereo audio source
can be connected. Users will be able to
monitor them, one at a time, using the 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.)
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 780-01’s all-digital signal path.
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There is, however, an exception worth
noting. Circuitry associated with the stereo
input has sample rate conversion (SRC)
capability, allowing virtually any stereo digital audio signal to be connected. A signal
connected to the stereo input can have an
independent sample rate and timing reference while still being monitored correctly.
Refer to the Technical Notes section of this
user guide for a detailed review of the SRC
capability.
The Model 780-01’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.
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.
Note that unlike a TASCAM-type assembly, the two threaded fasteners associated
with the Model 780-01’s D-subminiature
connector use 4-40 threads. This complies
with the original design standard for D-sub
connectors.
On the Model 780-01 the stereo input uses
a 3-pin female XLR connector for interfacing with a digital audio source. The mating
Issue 2, April 2015
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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 780-01 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
cable should have a 3-pin male XLR connector wired such that the + signal goes
to pin 2, the – signal to pin 3, and shield
to pin 1.
Unbalanced AES3 digital audio signals
can also be used with the Model 780-01’s
inputs if external coupling transformers
(“baluns”) are utilized. These impedancematching (75 ohms to 110 ohms) and level
step-up transformer assemblies typically
provide a BNC connector on their input
and a 3-pin male XLR connector on their
output.
Monitor Outputs
The 25-pin female D-subminiature connector on the back panel labeled Digital
Monitor Outputs provides access to the
Model 780-01’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
Model 780-01/790 User Guide
Studio Technologies, Inc.
for Surround
other post-fader (level adjustable by the
user). The pre-fader monitor output channels are intended for connection to metering or monitoring equipment that requires
uninterrupted full-level signals. The postfader monitor output channels are intended
to be connected to a loudspeaker system
that provides seven main channels and
one subwoofer channel.
The monitor outputs are transformerbalanced 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 monitor outputs. The D-sub connector follows the TASCAM-type 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 AES3 balanced signal. 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 signals each
supplying the pre- and post-fader monitor
outputs.
A wiring assembly prepared for the Model
780-01’s 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.
Model 780-01/790 User Guide
Studio Technologies, Inc.
For compatibility with AES3 balanced
digital audio signals connect the D-sub’s
+ connections as signal high and the
– connections as signal low. In most applications a 3-pin male XLR connector will be
used. In this case the + connections would
go to pin 2 of each XLR, the – connection
to XLR pin 3, and the shield connection to
XLR pin 1. Refer to Figure 5 or Appendix A
for the connection details.
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 780-01 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
Pre-Fader Monitor Output
The pre-fader monitor output channels are
intended to connect to metering, measurement, or other signal monitoring equipment
that requires uninterrupted, full-level digital
audio signal sources.
Post-Fader Monitor Output
The post-fader monitor output channels
are designed for connection to digital
inputs on audio amplifiers associated with
monitor loudspeakers. Alternately, they can
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be connected to the inputs of loudspeakers that contain integrated amplifiers with
digital audio input capability.
Sync Input
The Model 780-01 requires a timing reference (sync) source so that the audio input
and monitor output signals will be interpreted correctly. A configuration setting
allows the source of sync to be selected.
The default setting uses the L/R input of
the currently selected input source which
can be either of the surround inputs or
the stereo input. While this is acceptable,
audio artifacts (clicks or noise) will typically occur when switching between input
sources. A better method is to connect a
dedicated timing reference signal to the
Model 780-01’s sync input connector. The
connected sync source must maintain a
stable relationship between itself and the
connected audio sources. The actual sync
source can be in one of several formats:
word clock, DARS (AES11), bi-level video,
or tri-level video.
An overview of the various compatible
timing reference signals might prove
worthwhile. Word clock is a digital signal
that is locked in phase and frequency to
the sample rate of the associated audio
sources. DARS (digital audio reference
source) is a timing signal compliant with
the AES11 standard. It’s sometimes referred to as “AES3-black.” Technically it is
similar to an AES3 signal but is generated
specifically as a timing reference signal.
Bi-level video sync signals were originally
provided to support NTSC (United States)
and PAL (European) analog broadcast
applications, although they continue to be
used by contemporary digital video equipment. Tri-level sync signals were primarily
associated with facilities that upgraded to
Issue 2, April 2015
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support high-definition (HD) video signals,
however the need for this type of sync signal seems to be waning. The Model 780-01
supports both bi-level and tri-level signals
at numerous rate combinations, allowing
for compatibility with various worldwide
video formats.
With the wide range of allowable sync
sources proper Model 780-01 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 780-01’s back
panel. For flexibility the Model 780-01’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 780-01’s
sync input would typically want to have
the input termination enabled. If the sync
signal connected to the Model 780-01 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 monitor outputs. The Model
780-01’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
Model 780-01/790 User Guide
Studio Technologies, Inc.
for Surround
of this type are commonly referred to as
GPI inputs. While the input circuitry is
protected from over-current and static discharge (ESD), care should be taken to prevent nasty signals from reaching them. The
inputs are active only when held in the low
state; they can’t be configured to change
state (“latch”) in response to a logic pulse.
A 9-pin D-subminiature connector (DE-9F)
is used for the remote control inputs. Refer
to Figure 6 or Appendix A for connection
details. Note that pin 4 (remote common)
connects to the Model 780-01’s internal
circuit common connection as well as to
the Model 780-01’s chassis and mains
earth connections. Figure 6 also shows
two spare remote control inputs (pins 8
and 9). These are provided for future applications and should remain unconnected.
Signal
Pin
Direction
Data Shield
1
Shield
Remote Mute All
5
Input
Remote Dim
6
Input
Remote Spare 1
8
Input
Remote Spare 2
9
Input
Remote Common
4
Common
Note: Connector type on Model 780-01 is 9-pin female
D-subminiature (DE-9F). Connector uses 4-40
threaded inserts for locking with mating plug.
Figure 6. Connections for Remote Control
Inputs
Connecting the Model 780-01
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 780-01 Central Controller. This is
used to interface the unit with Model 790
Control Consoles. Refer to Figure 7 or
Appendix A for details. A 9-pin female
Model 780-01/790 User Guide
Studio Technologies, Inc.
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 780-01 is 9-pin female
D-subminiature (DE-9F). Connector uses 4-40
threaded inserts for locking with mating plug.
Figure 7. Connections between Model 780-01
and Model 790 and Model 71
D-sub connector (DE-9F) labeled To/From
Central Controller, is provided on the back
panel of each Model 790 Control Console.
A cable with 9-pin male D-sub (DE-9M)
connectors on each end is used to interconnect the Model 780-01 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 780-01’s connector pinout scheme was designed to allow creation
of an interconnecting cable which uses
commonly available 2-pair audio cable.
This cable, consisting of two twisted pairs
each with an individual shield, is typically
small in diameter, flexible, and available in
many colors. One pair and shield can be
used for the data connection (pins 1 and 6)
while the other pair and shield can be used
for the DC connections (pins 4 and 9). This
implementation has the advantages of
providing a shield for the data path and a
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more robust common (return path) connection (two conductors including the shield)
for the DC power circuit.
A few simple calculations are required to
determine the maximum cable length when
fabricating a cable to be used when connecting a Model 780-01 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
780-01 to a Model 790. The Model 780-01
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 780-01 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.
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Additional Control Consoles
Some installations may benefit from the
Model 780-01’s ability to be controlled by
additional control consoles. At least one
Model 790 Control Console must be connected to the Model 780-01 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 780-01.
When connecting multiple control consoles
to a Model 780-01 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 780-01 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.
Model 780-01/790 User Guide
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for Surround
AC Mains Power
The Model 780-01 operates directly from
AC mains power over a range of 100 to
240 V, 50/60 Hz. Being a “universal input” device, there are no switches to set
or jumpers to install to match a location’s
mains voltage. The unit uses a 3-pin IEC
320 C14-type inlet connector to mate with
a detachable mains cord. All units are supplied with a mains cord that has a NorthAmerican-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 780-01
does not contain an AC mains disconnect switch; the AC mains cord plug
serves as the disconnection device.
Safety considerations require that the
plug and associated outlet be easily
accessible to allow rapid disconnection of AC mains power should it prove
necessary.
As soon as mains power is applied the
Model 780-01 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 780-01’s main logic device. After
a few seconds initial system operation will
commence and the two LEDs will perform
Model 780-01/790 User Guide
Studio Technologies, Inc.
their intended functions. Once operating
data is being interchanged with the one
or more connected Model 790 or Model
71 Control Consoles the control console
status LED will light. The sync status LED
will light if a valid sync source has been
recognized. The sync status LED will flash
if a valid sync source is not recognized.
Also upon application of mains power, all
connected Model 790 units will go through
a power-up sequence, lighting each of its
LEDs in succession. Using its 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 780-01.
All connected Model 71 units will also go
through a power-up sequence after mains
power is applied to the Model 780-01.
Each of the Model 71’s three LEDs will
light momentarily. After these LEDs have
lit, the device address will be shown briefly
using the dim and reference level LEDs,
as shown in Figure 8 in the Configuration
section. When this is complete the Model
71 will begin normal operation. Its status
LED will light if communication is established with the Model 780-01. 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 780-01’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.
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Only after the Model 780-01 and all connected Model 790 and Model 71 units
have correctly powered up will full system
operation begin.
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 780-01 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
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• Overall Display Mode
• Reference Level in dB SPL
• Auto Reference Level Off
• Dim Level
• Remote Inputs
• LFE Downmix Level
• Pre-Fader Monitor Output Mode
• Input Delay Settings
• Post-Fader 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 780-01 into their configuration modes. Other connected Model
790 and Model 71 units will enter a standby mode. When the Model 780-01 enters
its configuration mode it will immediately
mute the pre- and post-fader 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.
Model 780-01/790 User Guide
Studio Technologies, Inc.
for Surround
As a user aid, a Model 790 that has entered
the configuration mode will have its mode
mute and mode solo LEDs (associated with
the input mute/solo section) light in an alternating manner. Other connected Model 790
units will indicate that they have entered the
standby mode by simultaneously flashing
their mode mute and mode solo LEDs.
To leave the configuration mode and return
the system to normal operation requires a
final action to be made. On the Model 790
unit that’s in its configuration mode press
and hold its configure button for two seconds. At this time any configuration changes
will be stored in nonvolatile memory and
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 780-01 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 780-01.
Model 780-01/790 User Guide
Studio Technologies, Inc.
Model 790 Device Address
A unique device address must be assigned
to each Model 790 Control Console that is
connected to a Model 780-01. The address
choices are A1, A2, A3, or A4, with the
default address being A1. As most installations will utilize only one Model 790 its
default setting is appropriate. For installations that use two, three, or four Model 790
units it’s important that each be configured
with a unique device address. Problems
will occur if more than one unit has the
same address. It’s important to highlight
the fact that the device address is the only
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 780-01,
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
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there might be cases where this resource
isn’t desired and it can be disabled.
Bass Management
The Model 780-01 incorporates flexible and
sonically excellent bass management capabilities. One configuration parameter is used
to enable or disable bass management
while three others are used to select the
characteristics of the associated audio filters. While the settings are simple to make,
great care must be taken to first review the
entire monitor system. Only after obtaining
a full understanding of the 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 monitor output and by
default is disabled. The crossover point of
the seven main channels’ bass management filters can be selected from among
four choices: 40, 50, 60, or 80 Hz. The
default value is 80 Hz. The slope of the
low-pass and high-pass filters associated
with the seven main channels’ bass management filters can be, as a group, selected. The choices are 12 dB-per-octave or
24 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 780-01 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
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surround or stereo input to also serve as
the system’s sync source. This fourth choice
is the default value.
Sync Input Termination
The sync input circuitry can be configured
to provide a 75 ohm termination impedance
to a connected source. When the sync input
is not terminated the input impedance is
very high, essentially applying no load to
the source. If the sync source is connected
only to the Model 780-01’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 780-01’s timing reference the sample
rate of the connected digital audio signals
must be explicitly specified. In most cases
the default value of 48 kHz will be appropriate. But alternately 44.1, 88.2, or 96 kHz
can also be selected. This setting enables
the internal clock and timing circuitry to correctly interpret the video sync signal’s relationship to the connected audio sources.
Reference Level
For consistent monitoring of audio signals
it’s often beneficial for users to be able to
easily set the post-fader 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 monitor output level to
Model 780-01/790 User Guide
Studio Technologies, Inc.
for Surround
be stored and then enabled by pressing
the Model 790 button labeled Reference
Level. Setting the reference level is very
simple but care is required:
1. Set up a precision sound pressure
level (SPL) measuring device at the
desired listening location.
2. Ensure that the StudioComm system
is in its normal operating mode, not the
configuration mode. Be certain that the
dim, mute all, reference level, downmix, input mute/solo, and output mute
functions are not active. The remote
mute all and remote dim functions
must also not be active.
3. Use the Model 790 Control Console to
select the input source that contains
the desired reference signal source,
e.g., pink noise. This would typically be
one of the surround inputs rather than
the stereo input.
4. Observing the SPL meter, adjust the
Model 790’s rotary level control until
the desired loudspeaker system reference level has been reached.
5. Being careful not to disturb the position of the rotary level control, enter the
configuration mode by pressing and
holding the configuration button for two
seconds. Once the configuration mode
has been entered the pre- and postfader monitor outputs 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
Model 780-01/790 User Guide
Studio Technologies, Inc.
will always be a negative number as it’s
always a value less than the maximum
output level. The reference level button
can now be released.
7. To complete the process the configuration mode must be exited. This
is performed by again pressing and
holding the configuration button for
two seconds. The new reference level
is now stored in the Model 780-01’s
nonvolatile memory. Only by repeating
the entire procedure can the value be
changed.
Once the configuration mode has been exited, the monitor outputs will again become
active. Confirm that the correct level has
been stored by pressing the reference level
button. The SPL meter should display the
desired level. If not, repeat the calibration
procedure to achieve the desired goal.
You might wonder why you have to press
and hold the reference level button for
five seconds before the selected value is
recognized. This is provided specifically so
that unauthorized users won’t accidentally
change the reference level while they experiment with the configuration mode. Only
if you know the “secret” will you be able to
store a new value.
Overall Display Mode
The Model 790’s 4-digit numeric display
can be configured to display the post-fader
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
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will show negative values, reaching –70.0
before the full mute function automatically
mutes the post-fader monitor outputs.
In the SPL mode the display can be configured to allow the output level to be
presented to users in terms of an actual
sound pressure level (SPL). It is used in
conjunction with the reference level in dB
SPL configuration and the stored reference
level. The SPL mode allows a user to see
a visual representation of the SPL level
that is present in the listening environment.
While it takes a little more care to correctly
implement the SPL display mode, it can
offer an enhanced experience for StudioComm users.
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
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 monitor output is not at the
reference value the display will show the
current value, in dB, relative to the reference level. The reference level in dB SPL
can be configured over a range of 70.0 to
100.0 dB in 1.0-dB steps. In many applications 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.
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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 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
Model 780-01/790 User Guide
Studio Technologies, Inc.
for Surround
the To Stereo downmix function is active,
LFE is reduced in level by 6 dB and routed
to both the left (L) and right (R) post-fader
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) post-fader monitor
output.
Pre-Fader Monitor Output
Mode
The pre-fader monitor output can be configured as to its place in the Model 780-01’s
signal flow. The choices are pre- or postdownmix. In the pre-downmix mode the
monitor output channels will not be impacted
by the state of the three downmix functions.
This setting would be appropriate if the prefader 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 monitor
output channels. If the post-downmix mode
is selected the pre-fader 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 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 prefader 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 cannot be
applied selectively. A configured delay time
is referenced to a sample rate of 48 kHz.
Model 780-01/790 User Guide
Studio Technologies, Inc.
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 Monitor Output
Level Offsets
To provide assistance during room calibration, the relative output levels of the
post-fader monitor output channels can be
adjusted over a limited range. The eight
channels can be adjusted in 0.5-dB steps
over a ±12-dB range. The default, of course,
is 0 dB for all channels. During configuration
the displayed value represents the dB level
difference as compared to the nominal output level. In most cases one channel should
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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 780-01 and other connected
Model 71 and Model 790 units will continue. When a Model 71 enters its configuration mode its three LEDs will no longer
perform their usual functions. Instead the
status LED will blink to indicate that configuration mode is active. Refer to Figure 8
for details.
Restore Factory Defaults
The restore factory defaults function is
provided primarily for factory use. In this
way a system can be quickly set so that
its default settings are selected. While you
are welcome to use this function, be careful so that your configuration efforts aren’t
wasted. Specifically, be aware that the reference level is reset to minimum level. All
the other parameters are fairly easy to set
up, but resetting the reference level would
require getting out an SPL meter and a
calibrated signal source. This is a hassle
you may not need!
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Figure 8. Model 71 Control Console Front and
Back Panels
Model 780-01/790 User Guide
Studio Technologies, Inc.
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 9 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 9. Model 71 Device Address Chart
Model 780-01/790 User Guide
Studio Technologies, Inc.
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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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Model 780-01/790 User Guide
Studio Technologies, Inc.
for Surround
Configuration—Model 790 Device Address and Stereo Input
Sample Rate Converter

Press and hold the Mute/Solo
button to display and configure the
Model 790’s device address and
stereo input sample rate converter.
This LED displays the configuration of the stereo input
sample rate converter (SRC). LED L not lit means SRC
is disabled; LED L lit means SRC enabled. Use the button
to change the configuration.
Use the Level control to change this
specific Model 790’s device address.
Address can be either A1, A2, A3, or A4.
See Note below.
Default:
Device address A1.
Stereo input sample rate converter enabled.
Note:
The Model 790’s device address is the only parameter stored in the Model 790. All other parameters are stored
in the Model 780-01.
Model 780-01/790 User Guide
Studio Technologies, Inc.
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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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Model 780-01/790 User Guide
Studio Technologies, Inc.
for Surround
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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Model 780-01/790 User Guide
Studio Technologies, Inc.
for Surround
Configuration—Overall Display Mode, Reference Level
in dB SPL, and Auto Reference Level Off
When the Mute All button is pressed, use the Channel Mute/Solo L and
R buttons to select the overall display mode. LED L lit means attenuation
mode is selected; LED R lit means SPL mode is selected. Use the buttons
to change the configuration.
When the Mute
All button is
pressed, use the
Reference Level
button to enable
or disable auto
reference level
off. When the
Reference Level
LED is lit auto
reference level
off is enabled.
Press and hold the Mute All button to
 display
and set the overall display mode,
the reference level in dB SPL, and auto
reference level off.
Default:
When the Mute All button is pressed,
use the Level control to adjust the
reference level in dB SPL.
Attenuation display mode selected.
85.0 dB SPL reference level.
Auto ref level off disabled.
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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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Model 780-01/790 User Guide
Studio Technologies, Inc.
for Surround
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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Model 780-01/790 User Guide
Studio Technologies, Inc.
for Surround
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 780-01 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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Studio Technologies, Inc.
for Surround
Operation
Now that you’ve installed and configured
the StudioComm system you’re ready to go.
You should find operation very easy. However, taking time to review and understand
this section of the user guide may prove
valuable.
Upon AC mains power up the system will
return to the last operating condition, including the selected source, downmix mode,
etc. As a precaution, however, the post-fader monitor output level will always return to
the minimum value. The rotary level control
or the reference level button must then be
used to set the level of the post-fader monitor output to the desired level.
Model 780-01 Central
Controller
The Model 780-01’s front panel contains
two LEDs. The control console status LED
will light whenever the Model 780-01 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 780-01. 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.
Model 780-01/790 User Guide
Studio Technologies, Inc.
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 7.1
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surround source to be “folded down”
(mixed) to stereo. The resulting signal is reproduced on the left (L) and right (R) monitor output channels. The To Mono function
allows a 7.1 surround or stereo source to
be converted to a single monaural channel.
The resulting signal is reproduced on the
center (C) monitor output channel.
Using the downmix functions simply
requires pressing the desired button. 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 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.
Monitor Output General
Functions
Four buttons and one rotary control are
associated with the post-fader monitor
output. The buttons control operation of
the reference level, mute all, dim, and LFE
low-pass filter functions. In addition the LFE
low-pass filter button can be used to enable
the display of the current sample rate. The
rotary level control is used to manually set
the post-fader monitor output level.
Reference Level
The reference level button sets the postfader monitor output level to a preset
value. Technical personnel, using a soundpressure-level (SPL) meter and precision
signal source, should have set this level to
meet the requirements of the specific monitoring environment. The LED associated
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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.
How the rotary level control functions
whenever the reference level mode is active depends on a configuration setting.
If the auto reference level off function is
disabled turning the rotary level control will
have no impact on the reference level function; it will remain active. If the auto reference level off function has been enabled
turning the rotary level control will cause
the reference level function to automatically turn off.
The LED associated with the reference
level button can also serve as a calibration aid. If the reference level mode is not
active, whenever the monitor output level
is selected to be the same as that stored
for the reference value the reference level
LED will flash. This exact level can be
reached through the use of the rotary level
control, either by itself or through the setting of the rotary level control in conjunction with the dim function. Whatever path
the monitor output takes to reach the reference level value, it will cause the reference
level LED to flash!
Mute All
Pressing the mute all button causes the
output channels associated with the postfader monitor output to mute. The 4-digit
display indicates the mute condition by
showing four dashes (– – – –). The mute
all button is always set to “latch” the function on and off. The LED associated with
the mute all button will light whenever
Model 780-01/790 User Guide
Studio Technologies, Inc.
for Surround
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 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!
Model 780-01/790 User Guide
Studio Technologies, Inc.
Note that the auto dim off function is not
active whenever dim is enabled due to
the remote dim function being active. This
allows remote control equipment, such
as a talkback system, to reliably dim the
monitor outputs.
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.
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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 monitor output level.
The level control provides the ability to
adjust the post-fader 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 0.5-dB change in level. In this case, to
traverse the entire level range would require rotating the control more than five full
turns. But the Model 790’s software detects
when the control is rotated more quickly
and increases the amount of level change
in dB per step. A little experimentation will
allow the user to acquire a good “feel” for
how best to use the control.
The reference level LED will flash when
the rotary level control sets the output level
to be the same as the stored reference
level. Whenever the rotary level control
attempts to set the output level to be less
than –70.0 dB, the 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/pressto-disable “latching” mode. Multiple channels
can be muted or soloed at the same time.
LEDs associated with a muted or soloed
channel will light to indicate that the function
is active.
Output Mute
The two buttons associated with the output
mute function provide a means of directly
muting the post-fader monitor output channels. These serve as an aid in observing
the performance of the loudspeaker system.
Model 780-01/790 User Guide
Studio Technologies, Inc.
for Surround
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
SUB button, and the 4-digit display are
used to select and display the input delay.
When the mute/solo button is pressed and
Model 780-01/790 User Guide
Studio Technologies, Inc.
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 780-01 is operating.
While pressing and holding the mute/solo
button the output mute SUB button can
be pressed to change the selected input
delay. Refer to Figure 10 for details. The
selected input delay will be stored in nonvolatile memory such that a power-down/
power-up cycle will not change the active
selection.
Display and Display Mode
The Model 790’s 4-digit LED display
shows the post-fader monitor output level
as either the amount of attenuation or
the sound pressure level (SPL). Both will
indicate level in dB. What the digits actually
represent will depend upon how the Model
790 has been configured.
Display in dB of Attenuation
If configured for the attenuation mode the
display will show the monitor output level
as an attenuation value in reference to the
maximum output. This is in the form of 0.5dB steps less than the maximum of 0.0 dB.
So a display of –40.5 would indicate that
the post-fader monitor output is set to be
40.5 dB below the maximum level. As the
rotary level control is moved counterclockwise the output level will go down and the
indicated value will get more negative.
Display in dB SPL
If the Model 790 is configured to display
the monitor output level in dB SPL, the
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
During normal operation, press and hold the Mute/Solo button
to view and change the input delay setting.
This LED displays the current
setting of the input delay.
LED not lit means input delay A
is selected; LED lit means input
delay B is selected. Press the
button to change the setting.
The display shows the currently
selected input delay in milliseconds.
Figure 10. Selecting the input delay
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.
Remote Control Inputs
As previously discussed in the Installation section of this user guide, two remote
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control signals can be connected to the
Model 780-01. 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.
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
Model 780-01/790 User Guide
Studio Technologies, Inc.
for Surround
allows adjustment of the post-fader 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 monitor output level.
Its operating characteristics are identical to
the rotary control in the Model 790 Control
Console, discussed earlier in this section.
Dim
The dim function allows the post-fader
monitor output level to be reduced by a
fixed amount. Its operating characteristics
are identical to those of the Model 790
Control Console, discussed earlier in this
section.
An indication is provided should the dim
button be pressed when button operation
has been disabled. Its associated LED will
flash briefly but no operating change will
occur. The LED will continue to display the
Model 780-01/790 User Guide
Studio Technologies, Inc.
status of the dim function as selected by
other Model 790 and Model 71 units.
Reference Level
The reference level button sets the postfader 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 780-01 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 780-01’s back panel.
Alternately, a configuration choice allows
the L/R input of the currently selected input
source to also serve as the system’s timing
reference. Whenever a valid sync signal
has been connected to the Model 780-01
the sync status LED, located on the unit’s
front panel, will light. The sample rate of
the monitor output channels will reflect the
rate of the sync input and, if a video sync
source is utilized, the configured rate.
If a valid sync signal is not present several visual indications are provided. On
the Model 780-01 the sync status LED will
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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 780-01’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 780-01’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 780-01 the monitor
outputs will automatically revert to an internally generated sample rate of 48 kHz with
no digital audio content present. This audio
“black” signal will allow most connected
equipment to continue to function correctly
with, of course, no meaningful audio signal
present. As soon as a valid sync signal is
again connected to the Model 780-01 the
monitor outputs will automatically switch to
their correct sample rate and audio signals
will again be present.
Power Down
Care was taken in the Model 780-01’s
design to minimize the chance that objectionable clicks, pops, or other obnoxious
audio signals will be present on the monitor outputs. A power-down circuit supplies
the main microcontroller integrated circuit
with an indication that a power loss is imminent. When this condition is detected
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the monitor outputs will switch to silence
(digital audio “black”) in preparation for a
complete loss of signal.
Power-Up Messages
Upon mains power being applied to the
Model 780-01 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 780-01 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 780-01’s main software
version
6. Displays FPgA
7. Displays Model 780-01’s logic device
(FPGA) software version
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 780-01.
The most likely cause would be incorrect wiring of the data pair linking the two
units. Err2 indicates that the Model 780-01
is having problems with its internal logic
Model 780-01/790 User Guide
Studio Technologies, Inc.
for Surround
device. (A high-speed field-programmable
gate array (FPGA) serves as the digital
“heart” of the Model 780-01 and without
it no audio activity can occur.) The only
way to remedy this condition is to first try
removing and reconnecting mains power.
(And that’s a long-shot as to whether
it would accomplish anything.) If Err2 continues to be displayed the Model 780-01
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)
capability. A digital audio signal connected
to that input can have its sample rate and
timing re-synchronized to match the Model
780-01’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 780-01.
The technical capabilities of the Model
780-01’s SRC function is stated in this
way: the sample rate of an input signal
Model 780-01/790 User Guide
Studio Technologies, Inc.
can range from 1/6 to six times the Model
780-01’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 780-01’s monitor output sample
rate is determined by the selected timing
reference (sync) signal and, if required,
a configured value. If a word clock, DARS
(AES11), or AES3 signal is the designated
sync source its rate will be the Model
780-01’s output sample rate. If a video
sync signal is connected, the Model
780-01’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 780-01’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 780-01’s SRC function to
re-synchronize a signal that proves most
valuable. For example, in typical postproduction and broadcast applications all
signals will have a sample rate of 48 kHz.
A Model 780-01 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 780-01’s
rate, thus allowing it to be monitored over
a loudspeaker system.
Issue 2, April 2015
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for Surround
Model 780-01 to Control
Console Connections
Channel Status, User, and
Validity Bits
Figure 7 gives a detailed description
of the signals that connect the Model
780-01 Central Controller to the one or
more Model 790 or Model 71 Control Consoles. The Model 780-01 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 780-01’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 780-01
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.
The non-audio bits that are part of the
AES3 digital audio monitor output channel
data are actively controlled by the Model
780-01’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 780-01’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 reconnect without issue. Upon disconnection of all control consoles the Model
780-01 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.
Issue 2, April 2015
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Model 780-01/790 User Guide
Studio Technologies, Inc.
for Surround
Specifications
Model 780-01 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
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
channel independently adjustable in 0.5-dB steps
over a ±12-dB range
Bass Management:
Crossover Frequency and Type: –6 dB @ 40, 50,
60, or 80 Hz, symmetrical for low-pass and highpass filters, maximally flat
Filter Slope: 12 dB-per-octave or 24 dB-per-octave
Overall Operation: on/off selectable
Type: balanced AES3 (110 ohms, 5 Vpp)
Downmix Functions: To 5.1, To Stereo, and
To Mono
Connector—Surround Inputs: 25-pin female
D-subminiature (DB-25F), AES59-2012-compliant
Control Console Interface:
Type: RS-485, 115.2 kbit/s, 8-1-N
Connector—Stereo Input: 3-pin female XLR
Polling Interval: 80 milliseconds, nominal
Sample Rate Conversion (SRC):
Application: available on the stereo input
Power: 12 Vdc, 500 mA maximum
Connector: 9-pin female D-subminiature (DE-9F)
Input Sample Rate Range: 8 to 216 kHz, limited
to 1/6 to 6 times the output sample rate
Remote Control Inputs: 2
Functions: remote mute all, remote dim
Latency: 1 millisecond, nominal
Type: 3.3 Vdc logic, activates on closure to system
common
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: 2 (16 channels total)
Configuration: organized as two surround (7.1),
one pre-fader, and one post-fader
Dynamic Range: >135 dB
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
Weight: 3.6 pounds (1.6 kg)
Type: balanced AES3 (110 ohms, 5 Vpp)
Connector: 25-pin female D-subminiature (DB25F), AES59-2012-compliant
Model 780-01/790 User Guide
Studio Technologies, Inc.
Issue 2, April 2015
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for Surround
Model 790 Control Console
Model 71 Control Console
Application: up to four Model 790 Control
Consoles can be connected to a Model 780-01
Central Controller
Application: up to three Model 71 Control
Consoles can be connected to a Model 780-01
Central Controller
Power: 12 Vdc nominal (9 Vdc minimum), maximum current 100 mA, provided by Model 780-01
Central Controller
Power: 12 Vdc nominal (9 Vdc minimum), maximum current 35 mA, provided by Model 780-01
Central Controller
Control Data:
Type: RS-485
Control Data:
Type: RS-485
Data Rate/Format: 115.2 kbit/s, 8-N-1
Data Rate/Format: 115.2 kbit/s, 8-N-1
Connector: 9-pin female D-subminiature (DE-9F)
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)
Dimensions (Overall):
3.20 inches wide (8.1 cm)
2.20 inches high (5.6 cm)
4.10 inches deep (10.4 cm)
Weight: 1.7 pounds (0.8 kg)
Weight: 0.8 pounds (0.4 kg)
Specifications and information contained in this
User Guide subject to change without notice.
Issue 2, April 2015
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Model 780-01/790 User Guide
Studio Technologies, Inc.
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 780-01 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 780-01 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
Connections for Digital Monitor Outputs
Signal
Direction
Signal
Shield
Data + (RS-485)
1
To/From Models 790/71
6
To/From Models 790/71
2
To/From Models 790/71
Data Shield
Pin
1
Remote Mute All
5
Input
Data – (RS-485)
Remote Dim
6
Input
Data Shield
Remote Spare 1
8
Input
Remote Spare 2
9
Input
Remote Input Common
4
Common
Note: Connector type on Model 780-01 is 9-pin female
D-subminiature (DE-9F). Connector uses 4-40
threaded inserts for locking with mating plug.
Connections for Remote Control Inputs
Model 780-01/790 User Guide
Studio Technologies, Inc.
Pin
Direction
DC + (12 V)
4
To Models 790/71
DC – (12 V Return)
9
To Models 790/71
DC Power Shield
5
To/From Models 790/71
Note: Connector type on Model 780-01 is 9-pin female
D-subminiature (DE-9F). Connector uses 4-40
threaded inserts for locking with mating plug.
Connections between Model 780-01 and
Model 790 and Model 71
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Appendix B—Sync Input Sources
The Model 780-01’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 780-01/790 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 780-01/790 User Guide
Studio Technologies, Inc.
Issue 2, April 2015
Page 49
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