Studio Technologies StudioComm 760-01 User manual

50245-1220, Issue 5
© 2020 by Studio Technologies, Inc., all rights reserved
www.studio-tech.com
Model 760-01 Central Controller and
Model 77 Control Console
User Guide
Issue 5, December 2020
This User Guide is applicable for systems consisting of:
Model 760-01: serial number M760-01-00151 and later with
software version 4.20 and higher and FPGA version 4.15 and higher;
Model 77: serial number M77-00151 and later with software version 4.20 and higher
for Surround

This page intentionally left blank.

Model 760-01/77 User Guide Issue 5, December 2020
Studio Technologies, Inc. Page 3
for Surround
Table of Contents
Revision History ........................................................... 4
Introduction ................................................................... 5
Installation .................................................................... 9
Configuration ................................................................16
Operation ......................................................................37
Technical Notes ............................................................44
Specifications ...............................................................48
Appendix A—Connection Pin-Out Charts .....................50
Appendix B—Sync Input Sources ................................51
Appendix C—Downmix Formulas ................................52

Issue 5, December 2020 Model 760-01/77 User Guide
Page 4 Studio Technologies, Inc.
for Surround
Revision History
Issue 5, December 2020:
• Revised how dim values are stated. Now are four positive dB values. Operation does not
change. For clarification only.
Issue 4, October 2016:
• Revised text for error codes Err1, Err2, and Err3; added text for error code Err4.
Issue 3, April 2015:
• Revised specifications to reflect final audio performance measurements.
Issue 2, January 2015:
• Text clarifications.
• Reflects final product nomenclature (Model 760-01/Model 77).
Issue 1, May 2014:
• Initial release (as Model 76D-110/Model 77).

Model 760-01/77 User Guide Issue 5, December 2020
Studio Technologies, Inc. Page 5
for Surround
Introduction
What This User Guide Covers
This User Guide is designed to assist you
when installing and using the Model 760-01
Central Controller and one or more associat-
ed Model 77 or Model 71 Control Consoles.
Overview
As creating and distributing multi-channel
surround (5.1) and stereo audio material has
become a day-to-day reality, the ability to
simply and effectively monitor these sources
is imperative for recording, post-production,
and broadcast facilities. And with audio-with-
picture applications becoming so prevalent,
additional monitoring challenges have arisen.
Studio Technologies has addressed these
needs with the StudioComm for Surround
Model 760-01 Central Controller and the
Model 77 and Model 71 Control Consoles.
With digital audio inputs, digital monitor
outputs, support for multiple user control
surfaces, and an extensive set of operat-
ing resources it’s a simple task to integrate
a monitoring system into virtually any facil-
ity. The carefully selected group of features,
including surround and stereo inputs, con-
figurable input-signal time delay, multiple
pre- and post-fader 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 con-
temporary technology, as well as following
rigorous design practices, the system’s audio
quality is excellent.
A StudioComm for Surround system starts
with the Model 77 Control Console. It’s the
system’s “command center” and is designed
to reside at a user’s location, allowing fin-
gertip selection of all monitoring functions.
Numerous LED indicators provide com-
plete status information. A 4-digit numeric
display indicates the post-fader monitor
output level in real time. A major strength
of the Model 77 is its ability to configure,
under software control, many important
operating parameters. Intended for sec-
ondary monitoring locations, the Model 71
Control Console is a compact user control
surface. It provides three of the most basic
functions: a rotary level control, dim on/off
button, and reference level on/off button.
Most installations will use only one Model
77 Control Console. However, up to three
additional Model 77 or Model 71 Control
Consoles can also be connected. This
provides multiple users with full control
over a facility’s monitor system. And to
make installation simple, the Model 760-01
provides power for all connected Model 77
or Model 71 units.
The core of this StudioComm for Surround
system is the Model 760-01 Central Con-
troller. The one-rack-space unit contains
circuitry that supports balanced digital
audio inputs, balanced digital monitor
outputs, digital audio and control process-
ing, and interfacing for the user control
surface(s). The Model 760-01 provides
two surround (5.1) and three 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 in-
puts allow a sample rate of up to 192 kHz
and a bit depth of up to 24 to be directly
supported. Circuitry associated with one
of the stereo inputs provides sample rate
conversion (SRC) capability, allowing a
wide range of digital audio sources to be
monitored. Up to 340 milliseconds of input
delay can be selected to compensate for
processing delays in an associated video

Issue 5, December 2020 Model 760-01/77 User Guide
Page 6 Studio Technologies, Inc.
for Surround
Figure 1. Model 760-01 Central Controller Front Panel
Figure 2. Model 760-01 Central Controller Back Panel
Sync status
LED
Control console
status LED
Sync
input
Digital
monitor outputs
To/from
Models 77 &
71 Control
Consoles
AC mains
input
Remote control inputs
Digital surround (5.1 ) inputs A & B
and digital stereo inputs A & B
Stereo
input C
path. For flexibility, two delay values can be
configured, allowing real-time selection as
desired. A number of different signals can
serve as the Model 760-01’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 ac-
tively selected surround or stereo input
source can serve as the timing reference.
A range of surround (5.1) and stereo digital
monitor outputs are provided. The post-
fader surround and stereo monitor outputs
are intended for connection to monitor loud-
speaker systems. The pre-fader surround
monitor output can be used with metering
systems that require signals that aren’t im-
pacted by level control or other monitoring
functions. The stereo input C direct moni-
tor output allows an installation to directly
access the SRC capabilities. The monitor
outputs are compatible with equipment
that requires balanced AES3 digital audio
signals with an output impedance of
110 ohms and a signal level of 5 volts
peak-to-peak (Vpp).
A sophisticated bass management function
is integral to the Model 760-01’s design and
can be enabled if desired. Note however
that the bass management function is only
supported at sample rates of 44.1, 48, 88.2,
and 96 kHz. The overall goal of bass man-
agement is very simple: ensure that the
entire audio bandwidth of all channels can
be accurately monitored. Many loudspeak-
er systems have inherent low-frequency
limitations, preventing a true picture of the
source material from being presented. To
overcome this, the low-frequency energy
from the five channels associated with the
surround inputs and the two channels asso-
ciated with the stereo inputs can be sepa-
rated and routed to the subwoofer (SUB)
channel of the monitor outputs. Several of
the bass management functions can be
configured to match the requirements of
specific installations.

Model 760-01/77 User Guide Issue 5, December 2020
Studio Technologies, Inc. Page 7
for Surround
Figure 3. Model 77 Control Console Front Panel
Channel mute/solo
Mute/solo
mode
Post-fader surround
monitor output
• Surround/stereo
• Reference level
• Mute all
• Dim
• Rotary level control
Monitor output
level display
Input source
select
Downmix
Great care was taken in designing the
system’s architecture, ensuring that the
character of the audio input signals is
preserved. All audio processing, including
bass management, is performed in 32-bit
logic using a high-speed field-program-
mable gate array (FPGA) integrated circuit.
The Model 760-01 occupies one space
(1U) in a standard 19-inch rack. Digital
audio sources are interfaced with the
Model 760-01 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. Digital monitor output signal con-
nections are made using a 25-pin female
D-subminiature connector. One 9-pin
female D-subminiature connector is used
to connect the Model 760-01 with a maxi-
mum of four Model 77 or Model 71 Control
Consoles. A second 9-pin “D-sub” connec-
tor is used to interface with remote control
signals. AC mains power is connected di-
rectly to the Model 760-01, with an accept-
able range of 100 to 240 V, 50/60 Hz.
Additional Details
The Model 77 provides five buttons and
associated LEDs for selection of the sur-
round and stereo input sources to be moni-
tored. While in most cases only one input
source will be monitored at a time, stereo
input C can be selected for simultaneous
monitoring with one of the two surround
or other two stereo inputs. This allows
the two selected inputs to be combined
(“summed”).
It’s interesting to note that while each of
the two surround inputs has an LFE chan-
nel associated with it, the “.1” post-fader
surround monitor output is designated as
SUB (subwoofer), rather than LFE. This
terminology was carefully selected to high-
light 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 input channels, combining it with the
LFE content before routing the sum to the
subwoofer output.

Issue 5, December 2020 Model 760-01/77 User Guide
Page 8 Studio Technologies, Inc.
for Surround
The post-fader surround and stereo monitor
output levels can be controlled by way of a
large, easy-to-use rotary control. The con-
trol, actually a digital encoder, allows level
selection in precise 0.5-dB steps. The auto
mute all function causes the post-fader sur-
round and stereo monitor output channels
to automatically mute whenever the output
level control reaches maximum attenua-
tion. Using the reference level function, the
post-fader surround and stereo monitor
output levels can be set to a pre-configured
value. This is provided for audio-with-picture
applications that require a specific monitor
output level. The reference level is easily
configured by taking an electronic “snap-
shot” of the desired monitor output level.
For user confirmation a 4-digit LED readout
can display the level of the post-fader sur-
round and stereo monitor output channels.
To match the needs of a facility, it can be
configured to display either the attenuation
level or the sound pressure level (SPL).
The dim function allows the post-fader sur-
round and stereo monitor output levels to be
reduced by a fixed dB amount. The dim lev-
el is configured from among four available
values. A mute all function allows the post-
fader surround and stereo monitor output
channels to be simultaneously muted. The
channel mute/solo section provides post-
fader surround and stereo channel monitor-
ing control, allowing a single channel to be
muted or monitored. Multiple channels can
also be simultaneously selected for muting
or “soloing.”
A special solo mode is also provided, called
channel pop solo, which offers a unique
aid when monitoring audio material. Chan-
nel pop solo allows the level of a single
post-fader monitor output channel to be
raised while the level of the other channels
is reduced. This helps to emphasize the
content on one channel without fully mut-
ing the others. Broadcast applications can
benefit from the channel pop solo mode by
allowing, for example, the center channel to
be highlighted while still maintaining some
level on the other channels. The amount of
level increase—the “pop”—as well as the
amount of attenuation can be configured to
meet the needs of specific applications or
users.
Two functions allow the input sources to be
checked for level or phase inconsistencies.
The surround to stereo downmix function is
used to create a stereo signal from the se-
lected surround (5.1) source. Key operating
parameters in the surround to stereo down-
mix function can be configured to meet the
requirements of an application. This can be
especially useful when support for specific
international broadcast standards is re-
quired. The stereo to mono downmix func-
tion allows audio on the left and right input
channels to be added (summed) and moni-
tored on the center output channel. The two
downmix functions can be simultaneously
enabled, allowing a surround source to be
checked for mono compatibility. The down-
mix functions always impact the post-fader
surround and stereo monitor outputs. A
configuration setting allows the pre-fader
surround monitor output to be selected for
pre- or post-downmix operation.
For flexibility, the StudioComm for Surround
system is designed to easily integrate with
equipment such as production intercom
systems, on-air or recording tally signals,
and audio consoles. Two remote-control
inputs provide access to the mute all and
dim functions. By providing access to these
functions, talkback or slate activity from an
audio console or other communications
system can control the level of the post-
fader surround and stereo monitor outputs.

Model 760-01/77 User Guide Issue 5, December 2020
Studio Technologies, Inc. Page 9
for Surround
Installation
In this section you will be installing the
Model 760-01 Central Controller in an
equipment rack. Connections to the digital
audio inputs and digital monitor outputs will
be made. A dedicated digital audio timing
reference signal can be connected to the
sync input. If desired, external equipment
will be interfaced to the remote control
inputs. A location will be selected for the
first Model 77 Control Console and it will
be connected to the Model 760-01. AC
mains power will be connected to the
Model 760-01. For advanced applications
up to three additional Model 77 or Model
71 Control Console units can be connect-
ed to the Model 760-01.
System Components
The main shipping carton contains one
each of the following: Model 760-01 Cen-
tral Controller, Model 77 Control Console,
9-pin D-sub interconnecting cable, and
user guide. Also included in the shipping
carton is a North-American-standard AC
mains cord. Your dealer or distributor
should provide an AC mains cord appro-
priate for destinations outside of North
America. Any additional Model 77 or Model
71 Control Consoles will be shipped in
separate cartons.
Mounting the Model 760-01
The Model 760-01 Central Controller
requires one space (1U) in a standard 19-
inch (48.3 cm) equipment rack. Secure the
Model 760-01 into the equipment rack us-
ing two mounting screws per side. Select
a location that is convenient for making
connections to the audio signals as well
as interfacing with the first (or only) Model
77 Control Console. A cable is supplied to
connect the Model 760-01 to the Model
77. If the needs of a specific installation
dictate, an alternate-length interconnecting
cable can be fabricated and used.
Audio Connections
Audio connections are made by way of two
25-pin female D-subminiature connectors
and one 3-pin female XLR connector. All
the connectors are located on the Model
760-01’s back panel. Refer to Figure 2 for
a detailed view of these connectors.
Audio Inputs
Two surround (5.1) and three stereo digi-
tal audio sources can be connected. All
sources can be monitored using the pre-
and post-fader surround and post-fader
stereo monitor output channels. A one-to-
one relationship is maintained between the
input and output channels, i.e., left input to
left monitor output, right input to right moni-
tor output, center input to center monitor
output, etc. (Of course this won’t be true in
the case where the user has enabled one
or both of the downmix functions.) Stereo
input C is also routed to the stereo input C
direct monitor output.
The audio inputs support digital audio sig-
nals with a sampling rate of up to 192 kHz
and a word length (depth) of up to 24 bits.
It’s best if the connected signal sources
maintain a common sample rate and tim-
ing reference. Having all signals “locked”
together helps to ensure proper handling
by the Model 760-01’s all-digital signal
control path.
There is, however, an exception worth not-
ing. Circuitry associated with stereo input
C has sample rate conversion (SRC) ca-
pability, allowing virtually any digital audio
signal to be connected. A signal connected

Issue 5, December 2020 Model 760-01/77 User Guide
Page 10 Studio Technologies, Inc.
for Surround
to stereo input C can have an independent
sample rate and timing reference and still
be monitored correctly. Refer to the Techni-
cal Notes section of this user guide for a
detailed review of the SRC capability.
The Model 760-01’s digital audio inputs
are intended for connection with balanced
digital audio sources that are compatible
with the AES3 standard. This signal type
has a nominal impedance of 110 ohms and
a nominal signal level of 5 Vpp.
One 25-pin female D-subminiature connec-
tor (DB-25F) is used to interface with the 16
channels associated with surround input A,
surround input B, stereo input A, and stereo
input B. Each of the eight physical connec-
tions supports two audio channels. Often a
wiring assembly prepared for these digital
audio inputs would typically be identical to
that of a TASCAM-type (AES59-compliant)
input assembly. An assembly of this type
would have eight 3-pin female XLR connec-
tors on one end and a 25-pin male D-sub-
miniature connector (DB-25M) on the other.
Refer to Figure 4 for details on connecting
with the 25-pin female D-subminiature
connector.
On the Model 760-01 stereo input C uses a
3-pin female XLR connector for interfacing
with a digital audio signal source. The mat-
ing cable should have a 3-pin XLR connec-
tor wired such that 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 760-01’s inputs
if external coupling transformers (“baluns”)
are utilized. These impedance-matching
(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 connec-
tor labeled Digital Monitor Outputs provides
access to the Model 760-01’s 16 channels
of digital audio monitor output: pre-fader
surround, post-fader surround, post-fader
stereo, and stereo input C direct. The pre-
fader surround monitor output channels
are intended for connection to metering or
monitoring equipment that requires uninter-
rupted full-level signals.
The post-fader surround monitor output
channels are intended to connect to a 5.1
loudspeaker system. The post-fader ste-
reo monitor output is provided to support a
separate set of stereo monitor loudspeak-
ers.
The stereo input C direct monitor output is
essentially a unity gain copy of the signal
connected to stereo input C. However, the
signal does pass through the sample rate
Signal Signal
Connections Channel High (+) Low (–) Shield
Surround Input A L/R 1 24 12 25
Surround Input A C/LFE 2 10 23 11
Surround Input A LS/RS 3 21 9 22
Stereo Input A 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 LS/RS 7 15 3 16
Stereo Input B 8 1 14 2
Notes: 1) All signals transformer-coupled digital audio;
balanced AES3 (110 ohms, 5 Vpp) compatible.
2) Connector type on Model 760-01 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,
Surround B, Stereo A, and Stereo B Digital Inputs

Model 760-01/77 User Guide Issue 5, December 2020
Studio Technologies, Inc. Page 11
for Surround
conversion (SRC) and input delay circuitry.
The impact made by these functions will
depend on the specific input signal and the
Model 760-01’s configuration settings.
The monitor outputs are transformer-
coupled balanced AES3 digital audio
signals with a source impedance of 110
ohms and a nominal signal level of 5 Vpp.
Signals of this type are normally intercon-
nected to destination equipment using
shielded twisted-pair cable terminated
with 3-pin male XLR connectors.
A cable assembly with a 25-pin male
D-subminiature connector (DB-25M) on
one end and the desired connectors on the
other end will be used for connecting to
the digital monitor outputs. The D-submin-
iature connector follows the TASCAM®-
type (AES59-compliant) wiring convention,
organizing the 25 pins into eight groups of
three pins each; one pin remains unused.
Each set of three pins provides an inde-
pendent interface. In the analog world this
would allow eight audio signals to be trans-
ported. But with AES3 digital audio signals
this allows support for 16 audio channels;
eight interfaces each supplying two audio
channels.
A wiring assembly prepared for the Model
760-01’s monitor outputs would typically
be identical to that of a TASCAM-type
output assembly. An assembly of this type
would have a 25-pin male D-subminiature
connector (DB-25M) on one end and eight
3-pin male XLR connectors on the other.
For compatibility with AES3 balanced
digital audio signals connect the D-sub’s
+ terminal as signal high and the – termi-
nal as signal low. In most applications a
3-pin male XLR connector will be used.
In this case the + terminal would go to
pin 2 of the XLR, the – terminal to XLR pin
3, and the shield terminal to XLR pin 1. Re-
fer to Figure 5 or Appendix A for the exact
connection details. Note that unlike a TAS-
CAM-type assembly, the two threaded fas-
teners associated with the Model 760-01’s
D-sub connectors use 4-40 threads. This
complies with the original design standard
for D-subminiature connectors.
Signal Signal
Connections Channel High (+) Low (–) Shield
Pre-Fader L/R 1 24 12 25
Pre-Fader C/SUB 2 10 23 11
Pre-Fader LS/RS 3 21 9 22
Stereo Input C Direct 4 7 20 8
Post-Fader L/R 5 18 6 19
Post-Fader C/SUB 6 4 17 5
Post-Fader LS/RS 7 15 3 16
Post-Fader Stereo 8 1 14 2
Notes: 1) All signals transformer-coupled digital audio;
balanced AES3 (110 ohms, 5 Vpp) compatible.
2) Connector type on Model 760-01 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 Surround Monitor Output
The pre-fader surround monitor output
channels are intended to connect to meter-
ing, measurement, or other signal monitor-
ing equipment that requires uninterrupted,
full-level digital audio signal sources.
Stereo Input C Direct Monitor Output
The stereo input C direct monitor output
is intended for use in site-specific applica-
tions. It provides an uninterrupted, full-level
digital audio signal source that is post-SRC
and input delay in the signal chain.

Issue 5, December 2020 Model 760-01/77 User Guide
Page 12 Studio Technologies, Inc.
for Surround
Post-Fader Surround Monitor Output
The post-fader surround monitor output
channels are designed for connection to
digital inputs on audio amplifiers associat-
ed with monitor loudspeakers. Alternately,
they could be connected to the inputs of
loudspeakers that contain integrated am-
plifiers with digital audio input capability.
Post-Fader Stereo Monitor Output
The post-fader stereo monitor output
channels are intended to support a stereo
loudspeaker system, either by connecting
to the digital input of an amplifier associ-
ated with a set of loudspeakers or directly
to a set of amplified speakers that provide
digital inputs.
Sync Input
The Model 760-01 requires a timing refer-
ence (sync) signal so that the digital audio
input and digital monitor output signals
will be handled correctly. A configuration
setting allows the source of sync to be the
L/R input of the currently selected sur-
round or stereo digital audio input. While
this is acceptable, audio artifacts (clicks or
noise) can occur when switching between
inputs. A better method is to connect a
dedicated timing reference signal to the
Model 760-01’s sync input connector. The
connected sync signal must maintain a
stable relationship between itself and the
digital audio input signals. The actual sync
source can be in one of several formats:
word clock, DARS (AES11), bi-level video,
or tri-level video.
An overview of the various compatible
timing reference signals might prove
worthwhile. Word clock is a digital signal
that is locked in phase and frequency to
the sample rate of the associated digital
audio sources. DARS (digital audio refer-
ence 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 generat-
ed specifically as a timing reference signal.
Bi-level video sync signals were originally
provided to support NTSC and PAL broad-
cast applications, although they continue
to be used by contemporary equipment.
Tri-level sync signals were primarily asso-
ciated with facilities that supported high-
definition (HD) video equipment however
the importance of this type of sync seems
to be waning. Both bi-level and tri-level
signals can be found at numerous rate
combinations, configured to allow for com-
patibility with the various video formats.
With the wide range of allowable sync
sources proper Model 760-01 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 con-
nector located on the Model 760-01’s back
panel. For flexibility this input can be con-
figured to be high-impedance (“floating”) or
terminated with an impedance of 75 ohms.
A sync source that is dedicated for use by
the Model 760-01’s sync input will typically
have input termination enabled. If the sync
signal connected to the Model 760-01 is
being connected (“multed”) to other inputs
it may be desirable for the termination to
be disabled. A general “rule of thumb” is
that termination should be applied only
at the location of the last physical device
using a sync signal.

Model 760-01/77 User Guide Issue 5, December 2020
Studio Technologies, Inc. Page 13
for Surround
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 surround and stereo monitor outputs.
The Model 760-01’s inputs use logic gates,
“pulled up” to 3.3 Vdc by way of resistors,
which are active whenever they are brought
to their logic low state. Inputs of this type
are commonly referred to as GPI inputs.
While the input circuitry is protected from
over-current and static discharge (ESD),
care should be taken to prevent nasty
signals from reaching them. The inputs are
active only when held in the low state; they
can’t be configured to change state (“latch”)
in response to a logic pulse.
A 9-pin D-subminiature connector is
used for the remote control inputs. Refer
to Figure 6 or Appendix A for the exact
connection details. Note that pin 4 (remote
common) connects to the Model 760-01’s
internal circuit common connection as well
as to the Model 760-01’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.
Connecting the Model 760-01
to the Model 77
A 9-pin female D-subminiature connec-
tor, labeled To/From Control Consoles, is
provided on the back panel of the Model
760-01 Central Controller. This is used to
interface the unit with Model 77 Control
Consoles. Refer to Figure 7 or Appendix A
for details. A 9-pin female D-sub connec-
tor, labeled To/From Central Controller, is
provided on the back panel of each Model
77 Control Console. A cable with 9-pin
male D-sub (DE-9M) connectors on each
end is used to interconnect the Model
760-01 with the Model 77 units. A cable is
included in the shipping carton. The cable
implements all nine connector pins in a
one-to-one manner.
Should an interconnecting cable of a differ-
ent 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 sup-
porting all nine pins, only four connections
are required: pin 1 (data +), pin 6 (data –),
pin 4 (DC +), and pin 9 (DC –). The Model
760-01’s connector pin-out scheme was
designed to allow creation of an inter-
connecting cable which uses commonly
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 760-01 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
Signal Pin Direction
Data + (RS-485) 1 To/From Models 77/71
Data – (RS-485) 6 To/From Models 77/71
Data Shield 2 To/From Models 77/71
DC + (12 V) 4 To Models 77/71
DC – (12 V Return) 9 To Models 77/71
DC Power Shield 5 To/From Models 77/71
Note: Connector type on Model 760-01 is 9-pin female
D-subminiature (DE-9F). Connector uses 4-40
threaded inserts for locking with mating plug.
Figure 7. Connections between Model 760-01
and Model 77 and Model 71

Issue 5, December 2020 Model 760-01/77 User Guide
Page 14 Studio Technologies, Inc.
for Surround
available 2-pair audio cable. This cable,
consisting of two twisted pairs each with an
individual shield, is typically sleek, flexible,
and available in many colors. One pair and
shield can be used for the data connections
while the other pair and shield can be used
for the DC connections. This implementa-
tion has the advantages of providing a
shield for the data path and a more robust
common connection (two conductors in-
cluding the shield) for the DC power circuit.
A few simple calculations are required to
determine the maximum cable length when
connecting a Model 760-01 to a Model 77.
The differential transmission scheme used
by the system’s RS-485 interface makes
an interconnection in excess of 1000 feet
(>300 meters) easily possible. The limiting
factor is typically the ability of the wiring to
pass the DC power supplied by the Model
760-01 to a Model 77. The Model 760-01
supplies 12 Vdc with a maximum current
of 500 milliamperes (mA).
The Model 77 requires a minimum of
9 Vdc, 100 mA, for correct operation. (The
voltage must be measured directly at the
Model 77’s 9-pin connector.) So the maxi-
mum interconnecting cable length is directly
related to the resistive voltage losses asso-
ciated with the two DC-carrying conductors.
As the Model 760-01 supplies 12 V and
the Model 77 requires 9 V minimum, this
directly leads to a 3 Vdc maximum drop due
to the interconnecting cable. Using Ohm’s
law it’s quite easy to determine whether
the selected cable will support the desired
interconnection length. Calculate the volt-
age drop by multiplying the total resistance
(in ohms) of the proposed cable by 0.1 (the
Model 77’s required current in amperes).
Remember to include the resistance in
both the DC + and DC – wires when
calculating the voltage drop. If it’s greater
than 3 V your cable is too long or the wire
gauge is too small.
Additional Control Consoles
Some installations may benefit from the
Model 760-01’s ability to be controlled by
additional control consoles. At least one
Model 77 Control Console must be con-
nected to the Model 760-01 Central Con-
troller. After this requirement has been met
up to three additional Model 77 or Model
71 Control Consoles can also be connect-
ed to and powered by the Model 760-01.
When connecting multiple control consoles
to a Model 760-01 all nine pins of each
interconnecting cable can be connected in
parallel (“multed”). Using this arrangement
the data and 12 Vdc power signals be-
tween all the units will be multed. A custom
cable implementation requires just four
pins to be connected: pin 1 (data +), pin 6
(data –), pin 4 (DC +), and pin 9 (DC –).
To make installation simple, a “bus” cable
assembly can be created using a short
length of ribbon cable with one male and
multiple 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 760-01 to Model 77 cable length
are discussed. Note the required current
for a Model 77 is 100 mA while a Model
71 requires only 35 mA. It’s important to
review this information prior to creating
the interconnection scheme to be used for
installing multiple Model 77 units.

Model 760-01/77 User Guide Issue 5, December 2020
Studio Technologies, Inc. Page 15
for Surround
AC Mains Power
The Model 760-01 operates directly from
AC mains power of 100 to 240 V, 50/60
Hz. Being a “universal input” device, there
are no switches to set or jumpers to install
to match a location’s mains voltage. The
unit uses a 3-pin IEC 320 C14-type inlet
connector to mate with a detachable mains
cord. All units are supplied with a mains
cord that has a North-American-standard
plug (NEMA 5-15L) on one end and an
IEC 320 C13 socket on the other. Units
bound for other destinations require that
the appropriate cord be used. The wire col-
ors in the mains cord must conform to the
internationally recognized color code and
should be terminated accordingly:
Connection Wire Color
Neutral (N) Light Blue
Line (L) Brown
Protective Earth (E) Green/Yellow
Safety Warning: The Model 760-01
does not contain an AC mains dis-
connect 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 760-01 will perform a power-up
sequence. The two LEDs on the right side
of the front panel will individually light in a
rapid right-to-left test sequence. Then the
LEDs will flash in cadence while the firm-
ware loads into the Model 760-01’s main
logic device. After just a few seconds initial
system operation will commence and the
two LEDs will perform their intended func-
tions. Once operating data is being inter-
changed with the one or more connected
Model 77 or Model 71 Control Consoles
the control console status LED will also
light. The sync status LED will light if a
valid sync source has been recognized.
The sync status LED will flash if a valid
sync source is not recognized.
Also upon application of mains power, all
connected Model 77 units will go through
a power-up sequence, lighting each of its
LEDs in succession. Using its 4-digit dis-
play, each Model 77 will then momentarily
display its address, its software version,
and the main and logic device software
versions of the associated Model 760-01.
All connected Model 71 units will also go
through a power-up sequence after mains
power is applied to the Model 760-01.
Each of the Model 71’s three LEDs will
light momentarily. After these LEDs have
been lit, the device address will be shown
briefly using the dim and reference level
LEDs, as shown in Figure 8 in the Con-
figuration section. When this is complete
the Model 71 will begin normal operation
and its status LED will light if communica-
tion is established with the Model 760-01.
If the Model 71’s status LED does not light
check to see if there is a device address
conflict among all connected control con-
soles and that all cables are connected
properly.
Should an error be detected during the
start-up process the two LEDs on the
Model 760-01’s front panel will remain
flashing in cadence. On the Model 77 units
a diagnostic code may be displayed. Refer
to the Technical Notes section of this user
guide for details.

Issue 5, December 2020 Model 760-01/77 User Guide
Page 16 Studio Technologies, Inc.
for Surround
Only after the Model 760-01 and all con-
nected Model 77 and Model 71 units have
correctly powered up will full system opera-
tion 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 need to be revised to meet
the needs of the specific installation. Many
of the configuration parameters will impact
the signal flow in to and out of the Model
760-01 Central Controller. Other parameters
affect how the one or more Model 77 Con-
trol Consoles will display status conditions
and respond to user commands. Most of the
configuration choices will be made using a
Model 77 Control Console. However, two
configuration choices are available for each
of the connected Model 71 Control Consoles.
Configurable Parameters
Many StudioComm functions can be config-
ured to meet the exact needs of an installa-
tion. A Model 77 Control Console is used
to display and select the desired system
configuration. Here’s an overview of what
can be configured:
• Model 77 Device Address (must be
unique for each unit!)
• Stereo Input C Sample Rate Converter
• Post-Fader Stereo Monitor Output
• Bass Management
• Mute/Solo Bass Management Mode
• Sync Source
• Sync Input Termination
• Audio-Synced-to-Video Sample Rate
• Reference Level
• Overall Display Mode
• Reference Level in dB SPL
• Auto Reference Level Off
• Dim Level
• Remote Inputs
• Surround to Stereo Downmix Levels
• Pre-Fader Surround Monitor Output
Mode
• Channel Pop Solo Mode Offset Levels
• Input Delay A and B
• 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 configu-
rable parameter is provided in the following
paragraphs.
Entering and Exiting the
Configuration Mode
A small button is located on the back of
each Model 77 Control Console, adjacent
to its 9-pin female D-sub connector. On any
connected Model 77 pressing and hold-
ing this button for two seconds places both
this specific unit and the Model 760-01
into their configuration modes. Other con-
nected Model 77 and Model 71 units will
enter a standby mode. When the Model
760-01 enters its configuration mode it will
immediately mute the monitor outputs as a
speaker protection measure. When a Model
77 enters the configuration mode its array
of buttons and LEDs no longer perform their
normal functions, instead they are used
to display the operating parameters and
reflect configuration changes as they are
made.

Model 760-01/77 User Guide Issue 5, December 2020
Studio Technologies, Inc. Page 17
for Surround
As a user aid, a Model 77 that has entered
the configuration mode will have its mute
and solo LEDs (associated with the chan-
nel mute/solo section) light in an alternating
manner. Other connected Model 77 units
will indicate that they have entered the
standby mode by simultaneously flashing
their mute and solo LEDs.
To leave the configuration mode and return
the system to normal operation requires
one last action to be made on the Model 77
unit that’s in its configuration mode; press
and hold its configuration button for two
seconds. Note that configuration changes
are stored in nonvolatile memory only after
the configuration mode has been exited.
Our apologies to those of you who find the
configuration button a pain to use, but it’s
supposed to be that way! Seriously, the top
of the button is slightly recessed from the
back panel, making it harder to accidentally
activate. We didn’t want normal operation to
cease because someone pushed a Model
77 into a “rats nest” of schedules, memos
from management, and empty coffee cups!
But a firm press with the fleshy part of an
index finger should do the trick.
There is no problem frequently “tweak-
ing” the system’s operating parameters
to achieve the desired performance. The
configuration data is stored in nonvolatile
memory, which is rated for thousands of
read and write cycles and a retention time
in tens of years. Note that memory integrat-
ed circuits are located in the Model 760-01
Central Controller as well as the Model 77
and Model 71 Control Consoles. The in-
dividual device address is stored in each
Model 77. The device address and button
configuration parameters are stored in the
Model 71. All other configuration param-
eters are stored in the Model 760-01.
Model 77 Device Address
A unique device address must be assigned
to each Model 77 that is connected to a
Model 760-01. The choices are A1, A2, A3,
or A4, with the default address being A1. As
most installations will find only one Model
77 utilized, its default setting is appropriate.
For installations that use a second, third, or
fourth Model 77 each unit must be config-
ured with a unique device address. Problems
will occur if more than one unit has the same
address! It’s important to highlight the fact
that the device address is the only setting
that must be done on each individual Model
77 unit. All other settings can be made on
any one of the connected Model 77 units.
Be sure that any selected address does
not conflict with addresses to be assigned
to Model 71 units.
Stereo Input C Sample Rate
Converter
Circuitry associated with stereo input C can
provide sample rate conversion (SRC) for
digital audio signals connected to that input.
The acceptable input range for sample rate
conversion is very wide, but is dependent
upon the output sample rate. With an output
sample rate of 48 kHz any signal with
a sample rate over a range of 8 to 216 kHz
can be properly monitored by the system.
This capability can be especially useful with
signals that are not synchronized with re-
spect to the others connected to the Model
760-01, even if the sample rate is identical.
The only compromise is that the SRC pro-
cess adds a fixed input-to-output (group)
delay of approximately 1 millisecond, a value
that shouldn’t impact most installations. As
such, it’s recommended that the sample rate
converter remain enabled. However there
might be special cases where this resource
isn’t desired and it can be disabled.

Issue 5, December 2020 Model 760-01/77 User Guide
Page 18 Studio Technologies, Inc.
for Surround
Post-Fader Stereo Monitor
Output
In addition to the post-fader surround moni-
tor output, a separate post-fader stereo
monitor output is also provided. By default
the stereo output can be enabled by a user.
In applications where stereo monitor loud-
speakers are not connected to the post-
fader stereo monitor output, the output can
be disabled. This can minimize confusion,
preventing a user from attempting to select
the post-fader stereo monitor output.
Bass Management
The Model 760-01 incorporates flexible
and sonically excellent bass manage-
ment capabilities. It is, however, limited to
functioning only at sample rates of 44.1,
48, 88.2, and 96 kHz. Five configuration
parameters are used to enable or disable
bass management as well as to select the
characteristics of the associated audio fil-
ters. While the settings are simple to make,
great care must be taken in first reviewing
the entire monitor system. Only after a full
understanding of the performance of the
associated surround and, if present, stereo
loudspeaker systems are determined can a
plan for bass management be established.
Bass management can be enabled so that
the function is active when the surround
post-fader monitor outputs are enabled. It
can also be independently enabled so that
it can be active when the stereo post-fader
monitor outputs are enabled. By default
bass management for both outputs is
disabled. The crossover point of the bass
management filters can be selected from
among four choices: 40, 50, 60, or 80 Hz.
The slope of the low-pass and high-pass fil-
ters associated with bass management can
be independently selected. The choices
are 12 dB-per-octave or 24 dB-per-
octave with the latter being the default.
Mute/Solo Bass Management
Mode
The Model 760-01’s mute/solo function
can be configured for how it performs in
applications where bass management has
been enabled. This is a somewhat-esoteric
topic but can be important in certain situa-
tions. The default setting for the mute/solo
bass management mode is for pre-bass
management. This means that if a channel
has been selected for, as an example, so-
loing then the bass management filters will
send any applicable low-frequency content
to the post-fader subwoofer output. So in
this case the solo function is really an “in-
put channel” solo since the actual acousti-
cal energy associated with that channel
will be reproduced by both the main chan-
nel and the subwoofer loudspeakers. So
while one is “soloing” a channel (or set of
channels) two or more loudspeakers may
be reproducing the signals.
The mute/solos bass management mode
can also be set for post-bass manage-
ment. When this mode is enabled a chan-
nel selected for soloing will cause only
its associated post-fader monitor output
channel to remain active. So if, for exam-
ple, one of the main surround input chan-
nels (one of the “5.” channels) is selected
for soloing then all post-fader output chan-
nels except that one will mute. The bass
management filters will remain enabled,
thus sending only the high-passed audio
energy from the soloed input channel to
the soloed output channel. Only if the LFE
channel has been selected for soloing will
the subwoofer output remain active. Typi-
cally the only reason why the post-bass

Model 760-01/77 User Guide Issue 5, December 2020
Studio Technologies, Inc. Page 19
for Surround
management mode would be selected is
when troubleshooting issues with the loud-
speaker system.
Sync Source
The Model 760-01 requires that the desig-
nated external timing reference (sync) be
defined. Three of the choices—word clock,
DARS, and video—are associated with a
signal that is connected to the sync input
BNC connector. The fourth choice allows
the L/R input of the currently selected sur-
round or stereo digital audio input to serve
as the system’s sync source.
Sync Input Termination
The sync input circuitry can be configured
to terminate the signal connected to the
back-panel sync input BNC connector.
When termination is selected a 75 ohm
load is applied to the signal. When the
sync input is not terminated the input im-
pedance is very high, essentially applying
no load to the source. If the sync source is
connected only to the Model 760-01 then
enabling termination is typically appropri-
ate. However, if the sync source is being
“shared” by multiple inputs then care must
be taken so that the signal is only termi-
nated by one device.
Audio-Synced-to-Video
Sample Rate
If a video sync signal is being used as the
Model 760-01’s timing reference the sam-
ple rate of the connected digital audio sig-
nals must be specified. In most cases the
default value of 48 kHz will be appropriate,
but rates from 32 to 192 kHz are available.
Reference Level
For audio-with-picture applications it’s
often beneficial for monitoring to be done
in reference to a known loudspeaker
level. This is often referred to as “mixing
to 85 dB” on the monitors. The Studio-
Comm for Surround system allows a
precise post-fader surround monitor output
level to be stored, and then enabled by
pressing the Model 77 button labeled
Reference Level. Setting the reference
level is very simple but care is required.
Typically this will be done in reference to
the surround monitor output, rather than
the stereo monitor output:
1. Set up a precision sound pressure
level (SPL) measuring device at the
desired listening location.
2. Place the StudioComm system in the
normal operating mode, not the config-
uration mode. Be certain that the dim,
mute all, reference level, and downmix
functions are not active. The remote
mute all and remote dim functions
must also not be active.
3. Use the Model 77 Control Console to
select the input source that contains
the desired reference signal source,
e.g., pink noise.
4. Observing the SPL meter, adjust the
Model 77’s rotary level control until the
desired loudspeaker system reference
level has been reached.
5. Being careful not to disturb the position
of the rotary level control, enter the
configuration mode by pressing and
holding the configuration button locat-
ed on the Model 77’s back panel.

Issue 5, December 2020 Model 760-01/77 User Guide
Page 20 Studio Technologies, Inc.
for Surround
6. Once the configuration mode has been
entered, all the monitor outputs will mute.
Press and hold the reference level but-
ton; its associated LED will begin to
flash.
After five seconds the LED will light
steadily to indicate that a “snapshot” of
the new reference level has been taken.
The Model 77’s numeric display will then
show the value of the new reference
level. The value shown will always be a
negative number as it’s always a value
less than the maximum output level.
The reference level button can now be
released.
7. To complete the process the configura-
tion mode must be exited. This is per-
formed by again pressing and holding
the configuration button for two seconds.
The new reference level is now stored in
the Model 760-01’s nonvolatile memory.
Only by repeating the entire procedure
can the value be changed.
Once the configuration mode has been ex-
ited, 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 recog-
nized. This is provided specifically so that
unauthorized users won’t accidentally
change the reference level while they experi-
ment with the configuration mode. Only if
you know the “secret” will you be able to
store a new value.
Overall Display Mode
The Model 77’s 4-digit numeric display
can be configured to display the post-fader
monitor output levels in either an attenua-
tion mode or an SPL mode. In the attenu-
ation mode the output level is shown as
a reduction in level, in dB, relative to the
maximum output level. When the rotary
control is used to set the output level to
its maximum the display will show 0.0. As
the rotary control is turned in the counter-
clockwise direction the display will show
negative values, reaching –70.0 before the
full mute function automatically mutes the
monitor outputs.
In the SPL mode the display can be con-
figured to allow the output level to be
presented to users in terms of the 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 Studio-
Comm users.
Reference Level in dB SPL
The reference level in dB SPL configuration
allows a specific SPL value to be associ-
ated with the stored reference level value.
In this way whenever the post-fader moni-
tor outputs are at the reference level, either
through activating the reference level func-
tion or manually adjusting the rotary level
control, the Model 77’s display will show the
configured SPL level. Whenever the moni-
tor output is not at the reference value the
display will show the current value, in dB,
relative to the reference level. The refer-
ence level in dB SPL can be configured
over a range of 70.0 to 100.0 dB in 1.0-dB
steps. In many applications selecting a