Studio Technologies 760-03 User Manual V.4.15

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for Surround

Model 760-03 Central Controller and

Model 77 Control Console

User Guide

Issue 3, April 2015

This User Guide is applicable for systems consisting of:

Model 760-03: serial number M760-03-00151 and later

software version 4.40 and higher and FPGA version 4.15 and higher;

Model 77: serial number M77-00151 and later with software version 4.40 and higher

with

www.studio-tech.com

50247-0415, Issue 3

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for Surround

Revision History ............................................................ 4

Introduction ................................................................... 5

Installation .................................................................... 9

Conﬁguration ................................................................17

Operation ...................................................................... 39

Technical Notes ............................................................46

Speciﬁcations ...............................................................50

Appendix A—Connection Pin-Out Charts ....................52

Appendix B—Sync Input Sources ................................54

Appendix C—Downmix Formulas .................................55

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Revision History

Issue 3, April 2015:

1. Revised speciﬁcations to reﬂect ﬁnal audio performance measurements.

Issue 2, January 2015:

1. Text clariﬁcations.

2. Reﬂects ﬁnal product nomenclature (Model 760-03/Model 77).

Issue 1,

1. Initial release (as Model 76DA-110/Model 77).

April 2014:

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Introduction

What This User Guide Covers

This User Guide is designed to assist you when installing and using the Model 760-03 Central Controller and one or more associated Model 77 or Model 71 Control Consoles.

Overview

As creating and distributing multi-channel surround (5.1) and stereo audio material has become a day-to-day reality, the ability to simply and effectively monitor these sources is imperative for recording, postproduction, 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 760-03 Central Controller and the Model 77 and Model 71 Control Consoles. With digital audio inputs, digital and analog monitor outputs, support for multiple user control surfaces, and an extensive set of operating resources it’s a simple task to integrate a monitoring system into virtually any facility. The carefully selected group of features, including surround and stereo inputs, conﬁgurable 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 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 77 Control Console. It’s the system’s “command center” and is designed

to reside at a user’s location, allowing ﬁngertip selection of all monitoring functions. Numerous LED indicators provide complete status information. A 4-digit numeric display indicates the post-fader monitor output level in real time. A major strength of the Model 77 is its ability to conﬁgure, under software control, many important operating parameters. Intended for secondary monitoring locations, the Model 71 Control Console is a compact user control surface. It provides three of the most basic functions: a 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 760-03 provides power for all connected Model 77 or Model 71 units.

The core of this StudioComm for Surround system is the Model 760-03 Central Controller. The one-rack-space unit contains circuitry that supports balanced digital audio inputs, balanced digital and analog monitor outputs, digital audio and control processing, and interfacing for the user control surface(s). The Model 760-03 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 inputs allow a sample rate of up to 192 kHz and a bit depth of up to 24 to be directly supported. Circuitry associated with one of the stereo inputs provides sample rate conversion (SRC) capability, allowing a wide range of digital audio sources to be monitored. Up to 340 milliseconds of input

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delay can be selected to compensate for processing delays in an associated video 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 760-03’s digital audio timing reference. For synchronization with a master timing reference a dedicated source of word clock, DARS (AES11), bi-level video, or tri-level video can be connected. Alternately, the L/R connection of the actively selected surround or stereo input source can serve as the timing reference.

A range of digital and analog surround (5.1) and stereo monitor outputs are provided. The post-fader surround and stereo digital and analog monitor outputs are intended for connection to monitor loudspeaker systems. The pre-fader surround digital monitor output can be used with metering systems that require signals that aren’t impacted by level control or other monitoring functions. The stereo input C direct digital monitor output allows an installation to directly access the

SRC capabilities. The digital 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 760-03’s design and can be enabled if desired. It can apply to both the surround and stereo digital and analog post-fader monitor output channels. 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 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 picture of the source material from being presented. To overcome this, the lowfrequency energy from the ﬁve channels associated with the surround inputs and the two channels associated with the stereo inputs can be separated and routed to the

Figure 1. Model 760-03 Central Controller Front Panel

Control console

status LED

Figure 2. Model 760-03 Central Controller Back Panel

AC mains input

Remote control inputs

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To /from

Models 77 &

71 Control

Consoles

Digital monitor

outputs

Analog monitor

outputs

Sync input

Stereo

input C

Digital surround (5.1) inputs A & B

and digital stereo inputs A & B

Sync status

LED

Mute/ solo

mode

for Surround

Channel mute/ solo

Downmix

Input source

select

Figure 3. Model 77 Control Console Front Panel

subwoofer (SUB) channel of the monitor outputs. Several of the bass management functions can be conﬁgured to match the requirements of speciﬁc installations.

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-programmable gate array (FPGA) integrated circuit.

The Model 760-03 occupies one space (1U) in a standard 19-inch rack. Digital audio sources are interfaced with the Model 760-03 using one 25-pin female D-subminiature connector and one 3-pin female XLR connector. A BNC connector is used to interface with an external sync source. Digital and analog monitor output signal connections are made using two 25-pin female D-subminiature connectors. One 9-pin female D-subminiature connector is used to connect the Model 760-03 with up to four Model 77 or Model 71 Control Consoles. A second 9-pin female “D-sub”

Monitor output level display

Post-fader surround monitor output

• Surround/ stereo

• Reference level

• Mute all

• Dim

• Rotary level control

connector is used to interface with remote control signals. AC mains power is connected directly to the Model 760-03, with an acceptable range of 100 to 240 V, 50/60 Hz.

Additional Details

The Model 77 provides ﬁve buttons and associated LEDs for selection of the surround and stereo input sources to be monitored. While in most cases only one input source will be monitored at a time, stereo input C can be selected for simultaneous monitoring with one of the two surround or other two stereo inputs. This allows the two selected inputs to be combined (“summed”).

It’s interesting to note that while each of the two surround inputs has an LFE channel associated with it, the “.1” post-fader digital and analog surround monitor outputs are designated as SUB (subwoofer), rather than LFE. This terminology was carefully 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

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main input channels, combining it with the LFE content before routing the sum to the digital and analog subwoofer outputs.

The post-fader surround and stereo digital and analog monitor output levels can be controlled by way of a large, easy-to-use rotary control. The control, actually a digital encoder, allows level selection in precise

0.5-dB steps. The auto mute all function causes the post-fader surround and stereo monitor output channels to automatically mute whenever the output level control reaches maximum attenuation. 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 “snapshot” of the desired monitor output level. For user conﬁrmation a 4-digit LED readout can display the level of the post-fader surround and stereo monitor output channels. To match the needs of a facility, it can be conﬁgured to display either the attenuation level or the sound pressure level (SPL).

The dim function allows the post-fader surround and stereo digital and analog monitor output levels to be reduced by a ﬁxed dB amount. The dim level is conﬁgured from among four available values. A mute all function allows the post-fader surround and stereo monitor output channels to be simultaneously muted. The channel mute/solo section provides post-fader surround and stereo channel monitoring control, allowing a single channel to be muted or monitored. Multiple channels can also be simultaneously selected for muting or “soloing.”

A special solo mode is also provided, called

channel pop solo, which offers a unique aid when monitoring audio material. Chan

nel pop solo allows the level of a single post-fader digital and analog 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 muting 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 selected surround (5.1) source. Key operating parameters in the surround to stereo downmix function can be conﬁgured to meet the requirements of an application. This can be especially useful when support for speciﬁc international broadcast standards is required. The stereo to mono downmix function allows audio on the left and right input channels to be added (summed) and monitored on the center output channel. The two downmix functions can be simultaneously enabled, allowing a surround source to be checked for mono compatibility. The downmix functions always impact the post-fader surround and stereo monitor outputs. A conﬁguration setting allows the pre-fader surround monitor output to be selected for pre- or post-downmix operation.

For ﬂexibility, the StudioComm for Surround system is designed to easily integrate with equipment such as production intercom systems, on-air or recording tally signals,

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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.

Installation

In this section you will be installing the Model 760-03 Central Controller in an equipment rack. Connections to the digital audio inputs, digital monitor outputs, and analog monitor outputs will be made. A dedicated digital audio timing reference signal can be connected to the sync input. If desired, external equipment will be interfaced to the remote control inputs. A location will be selected for the ﬁrst Model 77 Control Console and it will be connected to the Model 760-03. AC mains power will be connected to the Model 760-03. For advanced applications up to three additional Model 77 or Model 71 Control Console units can be connected to the Model 760-03.

System Components

The main shipping carton contains one each of the following: Model 760-03 Central Controller, Model 77 Control Console, 9-pin D-sub interconnecting cable, and user guide. Also included in the shipping carton is a North-American-standard AC mains cord. Your dealer or distributor should provide an AC mains cord appropriate for destinations outside of North America. Any additional Model 77 or Model 71 Control Consoles will be shipped in separate cartons.

Mounting the Model 760-03

The Model 760-03 Central Controller requires one space (1U) in a standard 19-inch (48.3 cm) equipment rack. Secure the Model 760-03 into the equipment rack using two mounting screws per side. Select a location that is convenient for making connections to the audio signals as well as interfacing with the ﬁrst (or only) Model 77 Control Console. A cable is supplied to connect the Model 760-03 to the Model 77. If the needs of a speciﬁc installation dictate, an alternatelength interconnecting cable can be fabricated and used.

Audio Connections

Audio connections are made by way of three 25-pin female D-subminiature connectors and one 3-pin female XLR connector. All the connectors are located on the Model 760-03’s back panel. Refer to Figure 2 for a detailed view of these connectors.

Audio Inputs

Two surround (5.1) and three stereo digital audio sources can be connected. All sources can be monitored using the preand post-fader surround and post-fader stereo monitor output channels. 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 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 signals 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

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maintain a common sample rate and timing reference. Having all signals “locked” together helps to ensure proper handling by the Model 760-03’s all-digital signal control path.

There is, however, an exception worth noting. Circuitry associated with stereo input C has sample rate conversion (SRC) capability, allowing virtually any digital audio signal to be connected. A signal connected to stereo input C can have an independent sample rate and timing reference and still be monitored correctly. Refer to the Technical Notes section of this user guide for a detailed review of the SRC capability.

The Model 760-03’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 connector (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 connections 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 connectors on one end and a 25-pin male D-subminiature 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 760-03 stereo input C uses a 3-pin female XLR connector for interfacing with a digital audio signal source. The mating cable should have a 3-pin XLR

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 760-03 is 25-pin female D-subminiature (DB-25F). Installer must provide male (DB-25M). Connector uses 4-40 threaded inserts for locking with mating plug.

3) Wiring scheme follows AES59-2012 convention. Standard TASCAM-type wiring harnesses are directly compatible, with the possible exception of 4-40 screw threads being required.

Figure 4. Connections for Surround A, Surround B, Stereo A, and Stereo B Digital Inputs

connector 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 760-03’s inputs if external coupling transformers (“baluns”) are utilized. These impedancematching (75 ohms to 110 ohms) and level step-up transformer assemblies typically provide a BNC connector on their input and a 3-pin male XLR connector on their output.

Digital Monitor Outputs

The 25-pin female D-subminiature connector labeled Digital Monitor Outputs provides access to the Model 760-03’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 digital monitor output channels are intended

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for connection to metering or monitoring equipment that requires uninterrupted full-level signals.

The post-fader surround digital monitor output channels are intended to connect to a 5.1 loudspeaker system. The post-fader stereo digital monitor output is provided to support a separate set of stereo monitor loudspeakers.

The stereo input C direct digital monitor output is essentially a unity gain copy of the signal connected to stereo input C. However, the signal does pass through the sample rate conversion (SRC) and input delay circuitry. The impact made by these functions will depend on the speciﬁc input signal and the Model 760-03’s conﬁguration settings.

The digital monitor outputs are balanced AES3 digital audio sources with a nominal impedance of 110 ohms and a nominal 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 Dsub connector (DB-25M) on one end and the desired connectors on the other end will be used for connecting to the digital monitor outputs. The D-subminiature con

nector 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 interface. In the analog world this would allow eight audio signals to be transported. But with AES3 digital audio signals this allows support for 16 audio channels; eight interfaces each supplying two audio channels.

A wiring assembly prepared for the Model 760-03’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 connec

tor (DB-25M) on one end and eight 3-pin male XLR connectors on the other.

For compatibility with balanced AES3 digital audio signals connect the D-sub’s + terminal as signal high and the – terminal as signal low. In most applications a 3-pin male XLR connector will be used. In this case the + terminal would go to pin 2 of the XLR, the – terminal to XLR pin 3, and the shield terminal to XLR pin 1. Refer to Figure 5 or Appendix A for the exact connection details. Note that unlike a TASCAM-type assembly, the two threaded fasteners associated with the Model 760-03’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

Notes: 1) All signals transformer-coupled digital audio; balanced AES3 (110 ohms, 5 Vpp) compatible.

2) Connector type on Model 760-03 is 25-pin female D-subminiature (DB-25F). Installer must provide male (DB-25M). Connector uses 4-40 threaded inserts for locking with mating plug.

3) Wiring scheme follows AES59-2012 convention. Standard TASCAM-type wiring harnesses are directly compatible, with the possible exception of 4-40 screw threads being required.

Figure 5. Connections for Digital Monitor Outputs

Stereo 8 1 14 2

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Pre-Fader Surround Digital Monitor Output

The pre-fader surround digital monitor output channels are intended to connect to metering, measurement, or other signal monitoring equipment that requires uninterrupted, full-level digital audio signal sources.

Stereo Input C Direct Digital Monitor Output

The stereo input C direct digital monitor output is intended for use in site-speciﬁc applications. It provides an uninterrupted, full-level digital audio signal source that is post-SRC and input delay in the signal chain.

Post-Fader Surround Digital Monitor Output

The post-fader surround digital monitor output channels are designed for connection to digital inputs on audio ampliﬁers associated with monitor loudspeakers. Alternately, they could be connected to the inputs of loudspeakers that contain integrated ampliﬁers with digital audio input capability.

Post-Fader Stereo Digital Monitor Output

The post-fader stereo digital 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.

Analog Monitor Outputs

The connector labeled Analog Monitor Outputs provides access to the Model 760-03’s 6-channel (5.1) surround and 2-channel stereo analog monitor outputs.

The surround analog monitor output channels are intended to connect to analog inputs associated with the surround loudspeaker system incorporated in a facility. The stereo analog monitor output allows support for a secondary set of stereo monitor loudspeakers.

The analog monitor output channels are designed for connection to audio ampliﬁers associated with monitor loudspeakers or to the inputs of loudspeakers that contain integrated ampliﬁers. The analog monitor outputs are electronically balanced and will perform optimally when driving loads of 2000 (2 k) ohms or greater. In most applications 3-pin male XLR connectors will be used to interface with the inputs on the associated ampliﬁers or ampliﬁed speakers. In this case the + terminal would go to pin 2 of the XLR, the – terminal to XLR pin 3, and the shield terminal to XLR pin 1.

Balanced operation of the analog monitor outputs is the preferred connection method but unbalanced operation does not pose a problem. To connect to an unbalanced load connect the + terminal as signal high, and only the Model 760-03’s shield terminal as the signal low/shield. Leave the – terminal unconnected. For correct unbalanced op

eration, it is important not to connect – and shield together.

The wiring scheme used by the D-subminiature connector complies with AES592012, as made popular by TASCAM. A wiring assembly prepared for the Model 760-03’s analog monitor outputs is identi

cal to that of a TASCAM-type output assembly. Please refer to Figure 6 for the exact connection details. Again note that unlike a TASCAM-type assembly, the Model 760-03’s D-sub connectors use 4-40 threads.

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Signal Signal Connections Channel High (+) Low (–) Shield

Surround L 1 24 12 25

Surround R 2 10 23 11

Surround C 3 21 9 22

Surround SUB 4 7 20 8

Surround LS 5 18 6 19

Surround RS 6 4 17 5

Stereo L 7 15 3 16

Stereo R 8 1 14 2

Notes: 1) Connector type on Model 760-03 is 25-pin female D-subminiature (DB-25M). Connector uses 4-40 threaded inserts for locking with mating plug.

2) Wiring scheme follows AES59-2012 convention. Standard TASCAM-type wiring harnesses are directly compatible, with the possible exception of 4-40 screw threads being required.

Figure 6. Connections for Analog Monitor Outputs

(DB-25F). Installer must provide male

Sync Input

The Model 760-03 requires a timing reference (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 surround 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 76003’s sync input connector. The connected sync signal must maintain a stable relationship between itself and the digital audio inputs. The actual sync source can be in one of several formats: word clock, DARS (AES11), bi-level video, or tri-level video.

An overview of the various compatible timing reference signals might prove worthwhile. Word clock is a digital signal that is locked in phase and frequency to the sample rate of the associated digital

audio sources. DARS (digital audio reference source) is a timing signal compliant with the AES11 standard. It’s sometimes referred to as “AES3-black.” Technically it is similar to an AES3 signal but is generated speciﬁcally as a timing reference signal. Bi-level video sync signals were originally provided to support NTSC and PAL broadcast applications, although they continue to be used by contemporary equipment. Tri-level sync signals were primarily associated with facilities that supported highdeﬁnition (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 compatibility with the various video formats.

With the wide range of allowable sync sources proper Model 760-03 operation should be easy to obtain. Extensive testing has been done using many different sync source types and rates. Interested users can refer to Appendix B of this user guide for details.

The external sync reference source is connected to the sync input BNC connector located on the Model 760-03’s back panel. For ﬂexibility this input can be conﬁgured to be high-impedance (“ﬂoating”) or terminated with an impedance of 75 ohms. A sync source that is dedicated for use by the Model 760-03’s sync input will typically have input termination enabled. If the sync signal connected to the Model 760-03 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.

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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 digital and analog monitor outputs. The Model 760-03’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 female D-subminiature connector is used for the remote control inputs. Refer to Figure 7 or Appendix A for the exact connection details. Note that pin 4 (remote common) connects to the Model 760-03’s internal circuit common connection as well as to the Model 760-03’s chassis and mains earth connections. Figure 7 also shows two spare remote control inputs (pins 8 and 9). These are provided for future applications and should remain unconnected.

Connecting the Model 760-03 to the Model 77

A 9-pin female D-subminiature connector, labeled To/From Control Consoles, is provided on the back panel of the Model 760-03 Central Controller. This is used to interface the unit with Model 77 Control Consoles. Refer to Figure 8 or Appendix A for details. A 9-pin female D-sub connector, labeled To/From Central Controller, is provided on the back panel of each Model 77 Control Console. A cable with 9-pin male D-sub (DE-9M) connectors on each end is used to interconnect the Model 760-03 with the Model 77 units. A cable is included in the shipping carton. The cable implements all nine connector pins in a one-to-one manner.

Should an interconnecting cable of a different length be required there’s no problem for one to be fabricated and used. While it can be wired in a one-to-one fashion supporting all nine pins, only four connections are required: pin 1 (data +), pin 6 (data –), pin 4 (DC +), and pin 9 (DC –). The Model 760-03’s connector pin-out scheme was designed to allow creation of an interconnecting cable which uses

Signal Pin Direction

Data Shield 1 Shield

Remote Mute All 5 Input

Remote Dim 6 Input

Remote Spare 1 8 In

Remote Spare 2 9 Input

Remote Common 4 Common

Note: Connector type on Model 760-03 is 9-pin female D-subminiature (DE-9F). Connector uses 4-40 threaded inserts for locking with mating plug.

Figure 7. Connections for Remote Control Inputs

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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 760-03 is 9-pin female D-subminiature (DE-9F). Connector uses 4-40 threaded inserts for locking with mating plug.

Figure 8. Connections between Model 760-03 and Model 77 and Model 71

for Surround

commonly available 2-pair audio cable. This cable, consisting of two twisted pairs each with an individual shield, is typically sleek, ﬂexible, and available in many colors. One pair and shield can be used for the data connections while the other pair and shield can be used for the DC connections. This implementation has the advantages of providing a shield for the data path and a more robust common connection (two conductors including the shield) for the DC power circuit.

A few simple calculations are required to determine the maximum cable length when connecting a Model 760-03 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 760-03 to a Model 77. The Model 760-03 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 maximum interconnecting cable length is directly re

lated to the resistive voltage losses associated with the two DC-carrying conductors. As the Model 760-03 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 voltage 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 760-03’s ability to be controlled by additional control consoles. At least one Model 77 Control Console must be connected to the Model 760-03 Central Controller. After this requirement has been met up to three additional Model 77 or Model 71 Control Consoles can also be connected and to powered by the Model 760-03.

When connecting multiple control consoles to a Model 760-03 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 760-03 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.

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AC Mains Power

The Model 760-03 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 appro priate cord be used. The wire colors in the mains cord must conform to the internationally recognized color code and should be terminated accordingly:

Connection Wire Color Neutral (N) Light Blue Line (L) Brown Protective Earth (E) Green/Yellow

Safety Warning: The Model 760-03 does not contain an AC mains discon nect 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 760-03 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 760-03’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 interchanged 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 760-03.

All connected Model 71 units will also go through a power-up sequence after mains power is applied to the Model 760-03. 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 9 in the Conﬁguration section. When this is complete the Model 71 will begin normal operation and its status LED will light if communication is established with the Model 760-03. If the Model 71’s status LED does not light check to see if there is a device address conﬂict among all connected control consoles and that all cables are connected properly.

Should an error be detected during the start-up process the two LEDs on the Model 760-03’s front panel will continue to ﬂash in cadence indeﬁnitely. On the Model 77 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 760-03 and all connected Model 77 and Model 71 units have correctly powered up will full system operation begin. It’s possible that audio signals will ﬁrst be present on the digital monitor outputs. The analog monitor outputs will only become active after a protection interval has elapsed. These outputs are muted using electro-mechanical relays that operate under software control.

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 760-03 Central Controller. Other parameters affect how the one or more Model 77 Control 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

• Post-Fader Stereo Digital and Analog 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 Digital Monitor Output Mode

• Channel Pop Solo Mode Offset Levels

• Input Delay A and B

• Post-Fader Digital and Analog Monitor Output Channel Level Offsets

The conﬁguration diagrams, located later in this section, give details on setting each parameter. An overview of each conﬁgu rable parameter is provided in the following paragraphs.

Many StudioComm functions can be conﬁgured to meet the exact needs of an installation. 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

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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 holding this button for two seconds places both this speciﬁc unit and the Model 760-03 into their conﬁguration modes. Other connected Model 77 and Model 71 units will

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enter a standby mode. When the Model 760-03 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.

As a user aid, a Model 77 that has entered the conﬁguration mode will have its mute and solo LEDs (associated with the channel 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 conﬁgure the 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 760-03 Central Controller as well as the Model 77 and Model 71 Control Consoles. The individual device address is stored in each Model 77. The device address and button conﬁguration parameters are stored in the Model 71. All other conﬁguration parameters are stored in the Model 760-03.

Model 77 Device Address

A unique device address must be assigned to each Model 77 that is connected to a Model 760-03. 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 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 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

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signals that are not synchronized with respect to the others connected to the Model 760-03, even if the sample rate is 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 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.

Post-Fader Stereo Digital and Analog Monitor Outputs

In addition to the post-fader surround digital and analog monitor outputs, separate post-fader stereo digital and analog moni tor outputs are also provided. By default the stereo outputs can be enabled by a user. In applications where stereo monitor loudspeakers are not connected to either of the post-fader stereo monitor outputs, the outputs can be disabled. This can minimize confusion, preventing a user from attempting to select the post-fader stereo digital and analog monitor outputs.

Bass Management

The Model 760-03 incorporates ﬂexible and sonically excellent bass management capabilities which can impact both the digital and analog post-fader monitor outputs. 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 ﬁlters. 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 sur round 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 ﬁlters associated with bass management can be independently selected. The choices are 12 dB-per-octave or 24 dB-peroctave with the latter being the default.

Mute/Solo Bass Management Mode

The Model 760-03’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 situations. 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, soloing then the bass management ﬁlters will send any applicable low-frequency content to the post-fader digital and analog subwoofer outputs. So in this case the solo function is really an “input channel” solo since the actual acoustical energy associated with that channel will be reproduced by both the main channel and subwoofer loudspeakers. So while one is “soloing” a channel (or set of channels) two or more loudspeakers may be reproducing the signals.

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The mute/solos bass management mode can also be set for post-bass management. When this mode is enabled a channel selected for soloing will cause only its associated post-fader digital and analog monitor output channels to remain active. So if, for example, one of the main surround input channels (one of the “5.” channels) is selected for soloing then all post-fader output channels 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. Typically the only reason why the post-bass management mode would be selected is when troubleshooting issues with the loudspeaker system.

Sync Source

The Model 760-03 requires that the designated 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 surround 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 impedance is very high, essentially applying no load to the source. If the sync source is connected only to the Model 760-03

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.

Audio-Synced-to-Video Sample Rate

If a video sync signal is being used as the Model 760-03’s timing reference the sample rate of the connected digital audio signals 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 StudioComm for Surround system allows a precise post-fader surround digital and analog 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 conﬁguration 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.

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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 located on the Model 77’s back panel.

6. Once the conﬁguration mode has been entered, all the monitor outputs (digital and analog) will mute. 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 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 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 760-03’s nonvolatile memory. Only by repeating the entire procedure can the value be changed.

Once the conﬁguration mode has been exited, the digital and analog monitor outputs will again become active. Conﬁrm that the correct level has been stored by pressing the reference level button. The SPL meter

should display the desired level. If not, repeat the calibration procedure to achieve the desired goal.

You might wonder why you have to press and hold the reference level button for ﬁve seconds before the selected value is recognized. This is provided speciﬁcally so that unauthorized users won’t accidentally change the reference level while they experiment with the conﬁguration mode. Only if you know the “secret” will you be able to store a new value.

Overall Display Mode

The Model 77’s 4-digit numeric display can be conﬁgured to display the post-fader digital and analog monitor output levels in either an attenuation mode or an SPL mode. In the attenuation 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 counterclockwise 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 StudioComm users.

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Reference Level in dB SPL

The reference level in dB SPL conﬁguration allows a speciﬁc SPL value to be associated with the stored reference level value. In this way whenever the post-fader digital and analog monitor outputs are at their reference level, either through activating the reference level function or manually adjusting the rotary level control, the Model 77’s display will show the conﬁgured SPL level. Whenever the monitor output is not at the reference value the display will show the current value, in dB, relative to the reference level. The reference level in dB SPL can be conﬁgured over a range of

70.0 to 100.0 dB in 1.0-dB steps. In many applications selecting a value of 85 would be appropriate, reﬂecting the widely used audio-for-picture 85 dB monitoring reference level. (Typically this 85 dB is really 85 dBC, indicating that a C-weighting ﬁlter has been applied to the measurement.) Other common reference SPL values, such as 82 dB and 87 dB, are well within the allowable range.

Auto Reference Level Off

When auto reference level off is enabled, the function automatically turns the reference level function off if a change is made to the rotary level control while the reference level function is active.

Dim Level

The dim function is used to reduce the post-fader digital and analog monitor output levels by a preset amount. The reduction is in dB relative to the post-fader monitor outputs’ current level. There are four dim level values available: –10.0, –15.0, –20.0, and –25.0 dB.

Remote Mute All

Two conﬁguration choices are associated with the remote mute all function: disabled and enabled. To utilize the remote mute all function simply requires you to select the enabled setting.

Remote Dim

Two conﬁguration choices are associated with the remote dim function: disabled and enabled. To utilize the remote dim function simply conﬁgure it for enabled.

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 signals and cannot be applied selectively. A conﬁgured delay time is referenced to a sample rate of 48 kHz. In the case of input signals with a sample rate of 48 kHz the delay range is 0 to 340 milliseconds in 1-millisecond steps. 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 77 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 will be selected. This could be appropriate in applications where multiple video display systems

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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.

Surround to Stereo Downmix Levels

The surround to stereo downmix function is a useful tool for checking the compatibility of surround (5.1) input signals with stereo and monaural playback environments. The exact technical formula for how the Model 760-03 handles the surround to stereo downmix function can be selected by way of four conﬁgurable parameters. The default settings create a good general-purpose function that’s effectively used by numerous users of Studio Technologies’ StudioComm for Surround products. But there are application-speciﬁc situations where modifying one or more of the parameters will be appropriate. This can be in response to a personal choice in monitoring methods or, more frequently, to meet the requirements of international broadcast standards.

When the surround to stereo downmix function is active the path from the left (L) input channel to the left post-fader output channel and the right (R) input channel to the right post-fader output channel is maintained. A conﬁguration choice allows the level of the L and R inputs routed to the L and R outputs to be selected. By default, when the surround to stereo downmix function is active the level of the L and R inputs remain at unity, with no gain or loss applied. An alternate setting allows the level of L and R input channels to be reduced

(attenuated) by 3 dB. (The available chang es in signal level can also be notated as 0 dB or –3 dB.)

When the surround to stereo downmix function is active the left surround (LS) input is routed to the left (L) post-fader monitor outputs; the right surround (RS) input is routed to the right (R) post-fader monitor outputs. By default the level of the LS and RS signals routed to L and R will be reduced (attenuated) by 3 dB. An alternate setting allows the levels to be reduced by 6 dB. (These settings can also be notated as –3 dB and –6 dB.)

When the surround to stereo downmix function is active the center (C) input is routed to both the left (L) and right (R) post-fader monitor outputs. By default the level of the C signal routed to L and R will be reduced (attenuated) by 6 dB. An alternate setting allows the attenuation level to be 3 dB. (These levels can also be notated as –3 dB and –6 dB.)

By default, when the surround to stereo downmix function is active the LFE channel associated with a 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 reduced by 6 dB and routed to both the left (L) and right (R) post-fader monitor outputs.

A last word on conﬁguring the surround to stereo downmix function: no matter what choices are made when the function is active the center (C), left surround (LS), right surround (RS), and subwoofer (SUB) postfader monitor outputs will fully mute.

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Pre-Fader Surround Digital Monitor Output Mode

The pre-fader surround digital monitor output can be conﬁgured as to its place in the Model 760-03’s signal ﬂow. The choices are pre- or post-downmix. In the pre-downmix mode the digital monitor output channels will not be impacted by the state of the downmix functions. This setting would be appropriate if the prefader surround digital monitor outputs were being routed to a storage system, routed to another facility, etc. In this case the action of a user enabling or disabling the downmix functions won’t impact the pre-fader surround digital monitor output signals. If the post-downmix mode is selected the pre-fader surround digital monitor outputs will reﬂect the actions of the downmix functions. This choice would be correct if, for example, level meters were connected to the pre-fader surround digital monitor outputs. In this scenario a user would want to visually observe the actions that the downmix functions impart on the signals.

Channel Pop Solo Mode Offset Levels

Two parameters can be conﬁgured that determine how the channel pop solo function will impact the output levels of the postfader digital and analog monitor outputs. The up offset level sets the amount of increase (gain) that a channel will experience when it is soloed in the channel pop solo mode. The down offset level sets the amount of decrease (attenuation) that the non-soloed channels will experience when a channel is active in the channel pop solo mode. Refer to Figure 11 for details.

Post-Fader Digital and Analog Monitor Output Level Offsets

To provide assistance during room calibration, the relative output levels of the post-fader surround and stereo digital and analog monitor output channels can be adjusted over a limited range. The eight channels can be adjusted in 0.5-dB steps over a ±12-dB range. During conﬁguration the displayed value represents the dB level difference as compared to the nominal output level. In most cases one surround and one stereo channel should serve as the overall reference level and not be changed. This is typically the center channel for surround and the left channel for stereo. The conﬁgured output level offset values apply to both the digital and analog surround stereo monitor outputs. It is not possible to conﬁgure a speciﬁc channel’s digital and analog monitor output level offsets to independent values.

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 the channels (six for surround, two for stereo) would be conﬁgured to have the same output level offset setting. For example, the six surround channels could all be conﬁgured to have a –3.5 dB output level offset. However, great care must be taken when

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conﬁguring a system in this manner. The dynamic range or noise ﬂoor of the audio signals will be impacted and extreme settings could lead to poor monitor system performance.

Restore Factory Defaults

The restore factory defaults function is provided primarily for factory use. In this way a system can be shipped with the default settings selected. While you are welcome to use this function, be careful so that your conﬁguration efforts aren’t wasted. Speciﬁcally, be aware that the reference level is reset to minimum level. All the other parameters are fairly easy to set up, but resetting the reference level would require getting out an SPL meter and a calibrated signal source. This is a hassle you may not need!

Model 71 Control Console Conﬁguration

Two conﬁguration choices are available on each Model 71. One is its device address, the other is the button disable mode. A small button is located on the back of each Model 71 Control Console, adjacent to the 9-pin female D-sub connector. Pressing and holding this button for two seconds places this speciﬁc unit in its conﬁgura tion mode; normal operation of the Model 760-03 and other connected Model 71 and Model 77 units will continue. When a Model 71 enters its conﬁguration mode its three LEDs will no longer perform their usual functions. Instead the status LED will blink to indicate that conﬁguration mode is active. Refer to Figure 9 for details.

Device Address

The dim and reference level LEDs will display the Model 71’s current device

Figure 9. Model 71 Control Console Front and Back Panels

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 77 Control Console. The choices are A1, A2, A3, and A4. All Model 71 units have a default device address of A4; Model 77’s units have a default device address of A1. This ensures that, in most cases, no change will have to be made. Refer to Figure 10 for details.

Button Disable

To disable the Model 71’s buttons, simulta neously press and hold both the dim and reference buttons for two seconds. When the disable request has been recognized the LEDs above both buttons will ﬂash rapidly. Release the buttons and they will no longer enable or disable their normal

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Address Dim LED Reference Level LED

A1 OFF OFF

A2 OFF ON

A3 ON OFF

A4 ON ON

Figure 10. Model 71 Device Address Chart

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.

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Conﬁguration—Entering and Exiting Conﬁguration Mode

Press and hold the conﬁguration



button for 2 seconds to enter or exit the conﬁguration mode.

These LEDs will light alternately when conﬁguration mode is active.

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Conﬁguration—Model 77 Device Address, Stereo Input C Sample Rate Converter, and Post-Fader Stereo Monitor Output

Press and hold the Mute/Solo button to display and conﬁgure the



Model 77’s device address, stereo input C sample rate converter, and post-fader stereo monitor output.

This LED displays the conﬁguration of the

stereo input C sample rate converter

(SRC). LED not lit means SRC is disabled; LED lit means SRC enabled. Use the button to change the conﬁguration.

These LEDs display the status of the post-fader stereo monitor output function. When LED Surround is lit the function cannot be enabled. When LED Stereo is lit the function can be enabled. Use the button to change the conﬁguration.

Default: Device address A1. Stereo input C sample rate converter enabled. Post-fader stereo monitor output can be enabled.

Note: The Model 77’s device address is the only parameter stored in the Model 77. All other parameters are stored in the Model 760-03

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Use the Level control to change this speciﬁc Model 77’s device address. Address can be either A1, A2, A3, or A4. See Note below.

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Conﬁguration—Bass Management and Mute/Solo Bass Management Mode

Use these buttons to select

bass manage ment 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 Stereo A lit means 24 dB-per-octave; LED Stereo B lit means 12 dB-per-octave.

This LED displays the conﬁguration of the surround output bass management. LED lit means surround output bass management enabled; LED not lit means surround output bass management disabled. Use the button to change the conﬁguration. See Note below.

This LED displays the conﬁguration of the stereo output bass management. LED lit means stereo output bass management enabled; LED not lit means stereo output bass management disabled. Use the button to change the conﬁguration. See Note below.

This LED displays the conﬁguration of the mute/solo

bass management mode. LED

lit means mute/ solo functions occur post-bass management; LED not lit means mute/solo functions occur prebass management. Use the button to change the conﬁguration.

Press and hold the Stereo C button to display and conﬁgure the bass



management and mute/solo bass management mode settings.

Default: Surround output bass management disabled. Stereo output 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. Mute/solo pre-bass management mode.

Note: Bass management capability only available at sample rates of 44.1, 48, 88.2, and 96 kHz.

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Use the Level control to select the

bass management crossover frequency. Choices are 40, 50,

60, or 80 Hz.

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Conﬁguration—Sync Source, Sync Input Termination, and Audio-Synced-to-Video Sample Rate

This LED displays the conﬁguration of the sync input termination. LED not lit means sync input is not terminated; LED lit means terminated with 75 ohms. Use the button to change the conﬁguration.



Press and hold

Use these buttons to select the sync source. LED Surround B lit means sync input, video; LED Stereo A lit means sync input, DARS; LED Stereo B lit means sync input, word clock; LED Stereo C lit means L/R of currently selected input.

the Stereo to Mono but ton to display and select the sync source, sync input termination, and audio-syncedto-video-sample rate.

Use the level control to adjust the audio- synced-to-video sample rate. Available sample rates are 32, 44.1, 48, 88.2, 96,

176.4, and 192 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

Press and hold the Reference Level button for 5 seconds to take a “snapshot”



of the level control’s setting at the time conﬁguration mode was entered. The Reference Level LED will ﬂash when the button is initially pressed and then light steadily when the “snapshot” has been taken. See Note below.

Default: Reference level set for –60.0 dB post-fader monitor output level.

Note: The 5-second button-press delay is a safety feature ensuring that the reference level will not be accidently

changed. To permanently store the new value, you must still exit the conﬁguration mode.

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Conﬁguration—Overall Display Mode, Reference Level in dB SPL, and Auto Reference Level Off

When the Mute All button is pressed, use the Channel Mute/Solo L and R buttons to select the overall display mode. LED L lit means attenuation mode is selected; LED R lit means SPL mode is selected. Use the buttons to change the conﬁguration.

When the Mute All button is pressed, use the Reference Level button to enable or disable

reference level off. When the

Reference Level LED is lit auto reference level off is enabled.

auto

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: Attenuation display mode selected.

85.0 dB SPL reference level. Auto ref level off disabled.

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When the Mute All button is pressed, use the Level control to adjust the

reference level in dB SPL

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Conﬁguration—Dim Level, Remote Mute All, and Remote Dim

This LED displays the conﬁguration of remote mute all. LED not lit means remote mute all is disabled; LED lit means enabled. Use the button to change the conﬁguration.

Use these buttons to select dim level. LED Surround B lit means –10 dB; LED Stereo A lit means –15 dB; LED Stereo B lit means –20 dB; LED Stereo C lit means –25 dB.

This LED displays the conﬁguration of remote dim. LED not lit means remote dim is disabled; LED lit means enabled. Use the button to change the conﬁguration.

Press and hold the Dim button to



display and select the dim level, remote mute all, and remote dim.

Default: –20 dB dim level. Remote mute all enabled. Remote dim enabled.

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Conﬁguration—Surround to Stereo Downmix Levels and Pre-Fader Surround Monitor Output Mode

These LEDs display the conﬁguration of the pre-fader surround 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.

Use these buttons to select the level change for the left and right channels when the surround

to stereo downmix function is active.

LED Surround A lit means 0 dB; LED Surround B lit means –3 dB.

Use these buttons to select the level change for the left surround and right surround channels when the surround

to stereo downmix function is active.

LED Stereo A lit means –3 dB; LED Stereo B lit means –6 dB.

Use this button to select the level change for the LFE channel when the surround to stereo downmix function is active. LED not lit means full attenuation; LED lit means –6 dB.

Use these buttons to select the level change for the center channel when the

surround to stereo downmix function is active.

LED LS lit means –3 dB; LED RS lit means –6 dB.



Press and hold the Surround to Stereo button to display and conﬁrm the surround to stereo downmix levels and prefader surround monitor output mode.

Default: L and R channel level change 0 dB when surround to stereo downmix function active. LS and RS channel level change –3 dB when surround to stereo downmix function active. C channel level change –6 dB when surround to stereo downmix function active. LFE level change full attenuation when surround to stereo downmix function active. Pre-fader surround monitor outputs pre-downmix.

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Conﬁguration—Channel Pop Solo Mode Offset Levels



Press and hold the Surround A button to display and select the channel pop solo up offset level.



Press and hold the Surround B button to display and select the channel pop solo down offset level.

Default: 6.0 dB channel pop solo up offset level. –6.0 dB channel pop solo down offset level.

When the Surround A button is pressed, use the level control to adjust the channel pop solo up offset level. The range is 0.0 to 12.0 in 0.5-dB steps.

When the Surround B button is pressed, use the level control to adjust the channel pop solo down offset level. The range is –0.0 to –12.0 in 0.5-dB steps and full mute. Full mute is selected by adjusting the level control past –12.0, at which point the display will show – – – –.

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Conﬁguration—Input Delay Settings



Press and hold the Stereo A button to display and select input delay A.



Press and hold the Stereo B button to display and select input delay B.

Default: Input delay 0 ms for both A and 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.

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Conﬁguration—Post-Fader Monitor Output Level Offsets



Press and hold the L button to conﬁgure the surround L level offset.



Press and hold both the L and Surround/ Stereo buttons to conﬁgure the stereo L level offset. Press and hold both the R and Surround/Stereo buttons to conﬁgure the stereo R level offset.



Press and hold the R button to conﬁgure the surround R level offset.

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Press and hold the C button to conﬁgure the surround C level offset.

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Press and hold the LFE button to conﬁgure the surround SUB level offset.



Press and hold the LS button to conﬁgure the surround LS level offset.

Press and hold the RS button to conﬁgure the surround RS 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 surround monitor output level offsets.

0.0 dB post-fader stereo monitor output level offsets.

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Conﬁguration—Restore Factory Defaults

Press and hold both the Surround/Stereo and Dim buttons for 5 seconds



to restore Model 77 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 C sample rate converter enabled. Post-fader stereo monitor outputs can be enabled. Surround output bass management disabled. Stereo output 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. Mute/solo pre-bass management mode. 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.

Warning: Each Model 77 unit must have a unique address. Restoring factory defaults will reset only this speciﬁc Model 77 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.

Remote mute all enabled. Remote dim enabled. L and R channel level change 0 dB when surround to stereo downmix function active. LS and RS channel level change –3 dB when surround to stereo downmix function active. C channel level change –6 dB when surround to stereo downmix function active. LFE level change full attenuation when surround to stereo downmix function active. Pre-fader surround monitor outputs pre-downmix.

6.0 dB channel pop solo up offset level. –6.0 dB channel pop solo down offset level. Input delay 0 ms for both A and B.

0.0 dB post-fader surround monitor output level offsets.

0.0 dB post-fader stereo monitor output level offsets.

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Operation

Now that you’ve installed and conﬁgured the system, you’re ready to go. You should ﬁnd operation very easy. However, taking time to study this section of the user guide may prove valuable.

Upon AC mains power up the system will return to the last operating condition, including the selected source, downmix modes, etc. As a precaution, however, the post-fader surround and stereo digital and analog monitor output levels will always return to their minimum value. The rotary level control or the reference level button must then be used to return the system to the desired monitor output level.

Model 760-03 Central

or Model 71 Control Consoles that have been connected. Two system functions can also be controlled by means of the remote control inputs.

Model 77 Control Console

To make things easy to describe, the Model 77’s operator functions are divided into six main groups: input source selection, downmix, monitor output general functions, channel mute/solo, display and display mode, and remote control inputs.

Any change made to any one Model 77 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.

Controller

The Model 760-03’s front panel contains two LEDs. The control console status LED will light whenever the Model 760-03 is communicating with the one or more connected Model 77 or Model 71 units. A ﬂashing control console status LED will indicate that the DC power output supporting the control consoles is in a short circuit or over-current condition. The control console status LED will not light when a Model 77 is in the conﬁguration mode or when the Model 77 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 760-03. A ﬂashing sync status LED indicates that a valid sync signal is not being received.

Control Consoles

StudioComm for Surround operation is controlled using the up to four Model 77

Input Source Selection

To select an input source press one of the ﬁve input source buttons. The corresponding LED will light to indicate that the input has been selected. Typically, only one source will be selected for monitoring at any one time. However, input stereo C can be selected by itself, or mixed (summed) with one of the other four inputs. To accomplish this is easy: simply press and hold input stereo C then press the button asso ciated with the other desired input source. The two corresponding LEDs will light. Alternately, press and hold the ﬁrst desired input (other than input stereo C) and then press the input stereo C button.

It’s possible (although unlikely) that selecting an input will result in the mute all function being enabled and an Err3 message being displayed. This would indicate a conﬂict between the sample rate of the selected input source and the bass management function. (Operation of the bass

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management function requires the source to have a sample rate of 44.1, 48, 88.2, or 96 kHz.) Selecting a source with a sample rate of 44.1, 48, 88.2, or 96 kHz will resolve the issue and normal operation will resume. Refer to the Technical Notes section of this user guide for additional details.

Downmix

Two downmix functions allow users to perform “real-world” audio format compatibility checks. One function allows a surround (5.1) signal to be “folded down” (mixed) to stereo. The other allows a stereo signal to be converted to mono. Using the downmix functions simply requires pressing the desired button. The buttons are set to always “latch” the functions on and off. An LED is located adjacent to each button and lights whenever its respective function is active. The downmix functions always impact the post-fader surround and stereo digital and analog monitor outputs. And, depending on the selected conﬁguration, they may also impact the pre-fader surround digital monitor output.

exact actions performed by the downmix functions refer to Appendix C at the end of this user guide.

Surround to Stereo

When the surround to stereo downmix function is enabled the LS, RS, and C channels associated with a surround source are combined (“folded down”) with the L and R signals to create a 2-channel stereo (left and right) signal. And, depending on the system’s conﬁguration, the LFE channel may also be combined with the L and R signals. The resulting stereo signal, sometimes known as LtRt, is routed to the L and R post-fader surround digital and analog monitor output channels. Also, whenever the surround to stereo downmix function is enabled the C, LS, RS, and SUB digital and analog monitor output channels are muted. By utilizing this downmix function phase relationships and inter-channel level issues can be quickly observed.

Stereo to Mono

A speciﬁc downmix function can only be enabled when it is applicable for the currently selected input source. This means that the surround to stereo downmix function can only be enabled when surround input A or B is selected.

The Model 77 associates the state of the downmix functions with the currently selected input. For example, if surround input A is the selected input source and the surround to stereo downmix function is enabled, this condition will be “remembered” when switching to one of the stereo input sources. Upon returning to surround input A, the surround to stereo downmix function will again become active. For details on the

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The stereo to mono downmix function combines the L and R audio channels to create a single-channel monaural signal. This signal is sent out the C surround digital and analog monitor output channels while the L, R, LS, RS, and SUB digital and analog monitor output channels are muted.

When a surround source has been selected for monitoring, the surround to stereo downmix function will automatically enable whenever the stereo to mono downmix function is enabled. This ensures that a user will hear a mono signal created by folding down all channels associated with the selected surround input.

for Surround

Monitor Output General Functions

Four buttons and one rotary control are associated with the post-fader digital and analog surround and stereo monitor output functions. The buttons control operation of the surround and stereo outputs, reference level, mute all, and dim functions. The rotary level control is used to manually set the post-fader surround and stereo digital and analog monitor output levels. These buttons and the rotary control do not impact the pre-fader surround and stereo input C direct digital monitor outputs.

Surround and Stereo Digital and Analog Outputs

The surround/stereo function allows selection between two different loudspeaker systems. When the surround output is selected the six post-fader surround channels associated with both the digital and analog monitor outputs are active. The channels associated with the post-fader digital and analog stereo monitor outputs are muted. When the stereo output is selected the left (L) and right (R) channels associated with both the post-fader digital and analog stereo monitor outputs become active; the six channels associated with the post-fader surround digital and analog monitor outputs mute.

Remember that the Model 77 Control Console can be conﬁgured to disable the surround/stereo button. If the button is pressed and the post-fader stereo monitor outputs are not selected, this must be the case!

Display Current Sample Rate

The surround/stereo monitor output select button is also used to display the system’s

current sample rate value. Pressing and holding the surround/stereo button will cause the current sample rate value to be displayed: 32.0, 44.1, 48.0, 88.2, 96.0,

176.4, or 192.0. This can be useful during troubleshooting or just for general interest. Once the button is released normal display operation will resume.

Reference Level

The reference level button sets the postfader surround and stereo digital and analog monitor output levels 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 associ

ated with the reference level button will light whenever the function is active. The 4-digit display will indicate the reference output level. Note that the system’s default reference level is –60.0 dB so “out of the box” the Model 77 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 post-fader surround or stereo digital and analog monitor output levels are precisely the same as that

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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 postfader surround and stereo monitor outputs take 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 post-fader surround and stereo monitor outputs to mute. The 4-digit display indicates the mute condition by showing four dashes (– – – –). The mute all button is always set to “latch” the function on and off. The LED associated with the mute all button will light whenever mute all is active. Note that if mute all is enabled via the remote mute all function, the mute all LED will ﬂash.

Dim

The dim function is provided for user convenience, allowing the post-fader surround and stereo digital and analog monitor output levels to be reduced by a ﬁxed amount. The Model 77’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. If the requested “dimmed” output level is equal to or less than –96.0 dB, the monitor outputs will go into full mute and the display will show four dashes (– – – –). 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 dis

cuss the auto dim off function. Whenever dim is enabled due to the dim button being pressed, and the rotary level control is active (reference level mode is not active), changing the setting of the rotary level control will automatically turn off dim. The auto dim off function is a unique attempt at protecting the aural health of users. No longer will there be a heart-stopping blast of audio when the dim button is pressed, supposedly to enable dim, but actually turning dim off because it was already enabled. It’s hard to explain unless you’ve experienced this in person—trust us, this situation can and does happen!

Note that the auto dim off function is not active whenever dim is enabled due to the remote dim function being active. This allows remote control equipment, such as a talkback system, to reliably dim the monitor outputs.

Rotary Level Control

The rotary level control is used to manually adjust the post-fader surround and stereo monitor output levels. The level control pro

vides the ability to adjust the post-fader surround and stereo digital and analog monitor output levels over a 70-dB range. Technically the rotary level control is a 24-step-perrevolution mechanical encoder. The amount of level change in dB per step (“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 77’s software detects when

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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 post-fader monitor output level to be the same as the stored reference level. Whenever the rotary level control attempts to set the output level for less than –70.0 dB, the post-fader surround and stereo monitor output channels will automatically mute. As previously discussed, the 4-digit display indicates the mute condi

tion by showing four dashes (– – – –).

If the mute all function is active the rotary level control won’t have an impact on the post-fader surround and stereo output levels. It’s also not active whenever the reference level function is active, except if the auto reference level off function has been enabled.

Channel Mute/Solo

The channel mute/solo functions allow speciﬁc channels to be selected for individual or group mute or “solo” monitoring. The functions impact the post-fader surround and stereo monitor outputs, taking place electrically “after” the input source selection, input delay, downmix, and level control functions. The relationship between the mute/ solo function and the bass management resources will depend on how the system has been conﬁgured.

The mute/solo mode button and the six channel mute/solo buttons, along with associated LEDs, work together to provide excellent operating ﬂexibility. The channel 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 channel mute/solo buttons. The buttons function in a press-to-enable/press-to-dis

able “latching” mode. Multiple channels can be muted or soloed at the same time. The LED associated with any muted or soloed channels is used to indicate that the function is active.

In most cases the mute/solo function will be conﬁgured to act in a pre-bass management signal ﬂow, creating an “input” mute/ solo function. In this case soloing one channel when bass management is enabled will result in audio content being reproduced in both the soloed channel as well as the subwoofer post-fader monitor output channels. Should the function be conﬁgured for post-bass management mode soloing a channel will result in only that speciﬁc monitor output channel reproducing the audio content.

Selecting the Solo Mode

As previously discussed in this user guide, solo operation can be selected between normal and channel pop. When the normal solo mode has been enabled the solo LED will light steadily. When the channel pop solo mode is enabled the solo LED will ﬂash. It’s easy to change from normal to pop solo, and vice-versa. Simply press and hold the mode button and use the surround to stereo button to select the desired solo mode. The LED associated with the surround to stereo button displays the active mode. Refer to Figure 11 for details. The selected mode will be stored in non-volatile memory so a power-down/power-up cycle will not change the selection.

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During normal operation, press and hold the Mute/Solo button to view and change the solo mode and input delay settings.



for Surround

This LED displays the current setting of the solo mode. LED not lit means normal; LED lit means channel pop. Press the button to change the mode.

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.

Figure 11. Solo mode and input delay settings

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 associated with video processing and display systems. During normal operation of the StudioComm system the active input delay, A or B, can be selected. The channel mute/solo button, stereo to mono button, and 4-digit display are used to display and select the input delay. When the mute/solo button is pressed and held the LED associated with the stereo to mono button indicates whether input delay A or input delay B is active. The 4-digit display will show the active delay time in milliseconds. While pressing and holding the mute/solo button the stereo to mono button can be pressed to change the selected input delay. Refer to Figure 11 for details. The selected input

The display shows the currently selected input delay in milliseconds.

delay will be stored in non-volatile memory so a power-down/power-up cycle will not change the selection.

Display and Display Mode

The Model 77’s 4-digit LED display shows the post-fader surround and stereo digital and analog monitor output levels as either the amount of attenuation or the sound pressure level (SPL). Both will indicate level in dB. What the digits actually represent will depend upon how the Model 77 has been conﬁgured.

Display in dB of Attenuation

If conﬁgured for the attenuation mode the display will show the post-fader moni tor output level as an attenuation value in reference to the maximum output. This is in the form of 0.5-dB steps less than the maximum of 0.0 dB. So a display of –40.5

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would indicate that the surround or stereo 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 77 is conﬁgured to display the post-fader digital and analog monitor out

put level in dB SPL, the 4-digit display will always show the output level in positive numbers. These numbers are intended to represent the sound pressure level in dB SPL, a ﬁgure that should directly relate to the actual sound pressure level that the surround or stereo 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.

Channel Pop Solo Display

As has been previously discussed, the channel pop solo mode offers a unique way of sonically highlighting an individual channel. A channel selected for soloing in this mode will have its level increased while the other non-soloed channels will be reduced in level. To highlight this condition the letters POP will appear in the 4-digit display whenever a channel is actively being soloed in the channel pop solo mode. This ensures that a user will understand that the post-fader monitor outputs no longer represent the true inter-channel level relationships.

Remote Control Inputs

As previously discussed in the Installation section of this user guide, two remote control signals can be connected to the Model 760-03 and then conﬁgured for operation. The functions are remote mute all and remote dim. When an external signal activates remote mute all the LED on the Model 77 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 77 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 and a limited number of pushbutton switches and LEDs for control and status display. The rotary level control allows adjustment of the post-fader surround and stereo monitor output levels. 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 dis plays on all the connected Model 77 and Model 71 units. And, as expected, changes made using a Model 77 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

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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, allows button operation to be disabled.

Rotary Level Control

The rotary level control is used to manually adjust the post-fader surround and stereo monitor output levels. Its operating charac teristics are identical to those of the Model 77 Control Console, discussed earlier in this section.

Dim

The dim function allows the post-fader surround and stereo monitor output levels to be reduced by a ﬁxed amount. Its operating characteristics are identical to those of the Model 77 Control Console, discussed earlier in this section.

An indication is provided should the dim button be pressed when button operation has been disabled. Its associated LED will ﬂash brieﬂy but no operating change will occur. The LED will continue to display the status of the dim function as selected by other Model 77 and Model 71 units.

Reference Level

The reference level button sets the postfader surround and stereo monitor output levels to their preset values. The operat ing characteristics are identical to those of the Model 77 Control Console, discussed earlier in this section.

An indication is provided should the reference button be pressed when button operation has been disabled. The associ ated 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 77 and Model 71 units.

Technical Notes

Loss of Sync

The Model 760-03 relies on an external timing reference (sync) source for proper operation. This can be in the form of an AES3, word clock, DARS (AES11), bi-level video, or tri-level video reference signal. In most cases the sync signal will be connected to the sync input BNC connector located on the Model 760-03’s back panel. Alternately, a conﬁguration choice allows the L/R input of the AES3 source currently selected for monitoring to also serve as the system’s timing reference. Whenever a valid sync signal has been connected to the Model 760-03 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 760-03 the sync status LED will ﬂash. On all connected Model 77 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 76003’s sync status LED will light steadily. On the Model 77 units the word sync will momentarily be displayed followed by a brief display of the monitor output sample rate. The sample rate will display as 32.0, 44.1,

48.0, 88.2, 96.0, 176.4, or 192.0, reﬂecting the impact of the sync source rate and the Model 760-03’s conﬁguration.

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If during normal operation the sync source changes from one valid rate to another a visual indication is provided. On the Model 77 units the new sample rate—32.0, 44.1,

48.0, 88.2, 96.0, 176.4, or 192.0—will momentarily be displayed.

Any time that a valid sync signal is not connected to the Model 760-03 the digital monitor output 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, of course with no meaningful audio signal present. As soon as a valid sync signal is again connected to the Model 760-03 the monitor outputs will automatically switch to their correct sample rate and audio signals will again be present.

Power Down

Great care was taken in the Model 760-03’s design to minimize the chance that clicks, pops, or other objectionable audio signals will be present on the post-fader digital and analog monitor outputs. A power-down circuit supplies the main microcontroller integrated circuit with an indication that a power loss is imminent. When this condition is detected the digital monitor outputs will switch to silence (digital audio “black”) in preparation for a complete loss of signal. Electromechanical relays associated with the analog monitor outputs will change to their mute state to minimize the chance of signal transients reaching the connected loudspeaker inputs.

Power-Up Messages

Upon mains power being applied to the Model 760-03 all connected Model 77 units will go through a power-up sequence.

The sequence starts by each of the indi vidual 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 77 and connected Model 760-03 software versions:

1. Displays 77

2. Displays Model 77’s software version

3. Displays Model 77’s unit address (A1, A2, A3, or A4)

4. Displays 760

5. Displays Model 760-03’s main software version

6. Displays FPgA

7. Displays Model 760-03’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 77’s 4-digit display. If Err1 displays it indicates that communication is not taking place with the Model 760-03. The most likely cause would be incorrect wiring of the data pair linking the two units. Err2 indicates that the Model 760-03 is having problems with its internal logic device. (A high-speed ﬁeld-programmable gate array (FPGA) serves as the digital “heart” of the Model 760-03 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 the error

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code continues to be displayed the Model 760-03 must be returned to the factory for service. Note that for the vast majority of StudioComm systems neither of these error codes, especially Err2, will ever appear.

Error Code Err3

As previously discussed in this user guide, the bass management function only supports input signals whose sample rate is

44.1, 48, 88.2, or 96 kHz. If during normal operation this condition is not met, it’s possible that Err3 will display and the mute all function will be automatically enabled. This will occur if the bass management function is conﬁgured to be enabled for either or both the surround and stereo post-fader monitor outputs and an input with a noncompatible sample rate has been selected. In this scenario, selecting a different input with 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 stereo input C 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 760-03’s internal timing. While it would be nice to proclaim that the engineers at Studio Technologies came up with a unique and exotic circuit to perform this function it’s really not the case. Several semiconductor companies provide “single-chip” SRC solutions and an excellent one from AKM was selected for the Model 760-03. The technical capabilities of the Model 760-03’s SRC function is stated in this way: the sample rate of an input signal can range from 1/6 to six times the Model 760-03’s output

sample rate, with the additional restriction that it must be no less than 8 kHz and no more than 216 kHz. The Model 760-03’s 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 760-03’s output sample rate. If a video sync signal is connected, the Model 760-03’s sample rate is selected as part of the conﬁguration process.

So in practice what can the SRC function accomplish? If the output sample rate is 48 kHz then a signal connected to stereo input C can have a sample rate from 8 to 216 kHz. Or, as another example, if the Model 760-03’s output sample rate is 96 kHz a signal connected to stereo input C can have its sample rate range from 16 to 216 kHz.

As useful as allowing one disparate sample rate to be converted to another, it may be the ability of the Model 760-03’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 760-03 and all of its normally connected input signals will be “locked” to the 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 stereo input C will cause the SRC function to “lock” it to the Model 760-03’s rate, thus allowing it to be monitored over a loudspeaker system. In addition, the stereo input C direct monitor output can be connected to other devices that ﬁnd need for the now-synchronized signal. In

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some cases it may be useful to connect the stereo input C direct monitor output to the input of a signal router, allowing an entire facility to access the signal.

Model 760-03 to Control Console Connections

Figure 8 gives a detailed description of the signals that connect the Model 76003 Central Controller to the one or more Model 77 or Model 71 Control Consoles. The Model 760-03 provides 12 Vdc for use by the control console’s circuitry. The DC output is current-limited to minimize the chance that a short-circuit condition will damage the Model 760-03’s circuitry. An asynchronous, bi-directional data interface links the connected units. The RS-485 hardware connection scheme operates at a rate of 115.2 kbit/s and uses an 8-N-1 data format. The Model 760-03 communicates with each Model 77 and Model 71 unit 20 times per second, receiving button and rotary level control information and sending LED and 4-digit display status data.

again connected. The control consoles will go through their standard power-up sequence and then normal operation will resume.

Channel Status, User, and Validity Bits

The non-audio bits that are part of the AES3 digital audio monitor output channel data are actively controlled by the Model 760-03’s software. The Channel Status bits use the Professional Use of Channel Status block. They indicate a word length of 24 and the current sample rate. The correct CRC is also calculated and inserted. The User bits are always set to 0. When a valid timing reference (sync) source is recognized by the system the Validity bits will be set to 1.

The Model 760-03’s hardware is capable of routing the C/U/V bit information from any of the L/R inputs, as well as the sync input, to the main logic device (FPGA) and then on to the digital audio transmitter (DIT) integrated circuits. This is provided for future use and is not active at this time.

“Hot” Disconnection of Control Consoles

There’s no problem relocating one or more Model 77 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 760-03 Central Controller will mute the internal digital audio channels as well as saving the current operating parameters. No clicks, pops, or other noises will occur when the Model 77 or Model 71 units are

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Speciﬁcations

Model 760-03 Central Controller

General Audio: Supported Sample Rates: 32, 44.1, 48, 88.2, 96,

176.4, and 192 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: 5 (18 audio channels) Conﬁguration: two surround (5.1) and three stereo

Type: balanced AES3 (110 ohms, 5 Vpp)

Connector—Surround Inputs and Stereo Inputs A & B: 25-pin female D-subminiature (DB-25F),

AES59-2012-compliant

Connector—Stereo Input C: 3-pin female XLR

Sample Rate Conversion (SRC): Application: available on Stereo Input C

Input Sample Rate Range: 8 to 216 kHz, limited to

1/6 to 6 times the output sample rate

Latency: 1 millisecond, nominal

Sync Source: conﬁgured to follow L/R of currently

selected input or signal connected to sync input

Sync Input: Compatible Sources: word clock, DARS (AES11),

bi-level video, tri-level video

Jitter: 4 ns pp maximum

Connector: BNC (per IEC 60169-8 Amendment 2)

Termination: 75 ohms, selectable on/off

Digital Monitor Outputs: 16 channels (8 pairs) Conﬁguration: organized as two surround (5.1)

and two stereo

Dynamic Range: >135 dB

Type: balanced AES3 (110 ohms, 5 Vpp)

Connector: 25-pin female D-subminiature

(DB-25F), AES59-2012-compliant

Analog Monitor Outputs: 8 Conﬁguration: organized as one surround (5.1)

and one stereo (2-channel)

Type: electronically balanced, source impedance 200 ohms

Nominal Level: +4 dBu @ –20 dBFS input source and level control at maximum setting

Maximum Level: +24 dBu into 2000 (2 k) ohms or greater

Frequency Response, Digital Inputs to Analog Monitor Outputs: 10 Hz-20 kHz +0.0/–0.3 dB @

48 kHz sample rate; –3 dB @ 64 kHz

Distortion (THD+N): 0.004%, ref 1 kHz, +4 dBu output

S/N Ratio: 89 dB, ref +4 dBu output

Dynamic Range: >109 dB

Crosstalk: –98 dB at 1 kHz; –97 dB at 16 kHz,

ref –1 dBFS input

Connector: 25-pin female D-subminiature (DB-25F), AES59-2012-compliant

Conﬁgurable Input Delay: 0 to 340 milliseconds @ 48 kHz sample rate (scales up or down depending on actual sample rate)

Post-Fader Monitor Output Level Offsets: each surround and stereo channel independently adjustable in 0.5-dB steps over a ±12-dB range. (Digital and analog outputs associated with a speciﬁc channel share the same setting.)

Bass Management: Supported Sample Rates: 44.1, 48, 88.2, and

96 kHz only

Crossover Frequency and Type:

60, or 80 Hz, symmetrical for low-pass and highpass ﬁlters, maximally ﬂat

Filter Slope: 12-per-octave or 24 dB-per-octave

Overall Operation: independent on/off selectable

for surround and stereo post-fader monitor outputs

–6 dB @ 40, 50,

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Downmix: Surround to Stereo and Stereo to Mono

Control Console Interface: Type: RS-485, 115.2 kbit/s, 8-1-N

Polling Interval: 80 milliseconds, nominal

Power: 12 Vdc, 500 mA maximum

Connector: 9-pin female D-subminiature (DE-9F)

Remote Control Inputs:

Functions: remote mute all, remote dim

Type: 3.3 Vdc logic, activates on closure to system

common

Connector: 9-pin female D-subminiature (DE-9F)

AC Mains: Requirement: 100 to 240 V, +10/–15%, 50/60 Hz,

15 W maximum

Connector: 3-blade, IEC 320 C14-compatible (mates with IEC 320 C13)

Dimensions:

19.00 inches wide (48.3 cm)

1.72 inches high (4.4 cm)

7.00 inches deep (17.8 cm)

Model 71 Control Console

Application: up to three Model 71 Control Con-

soles can be connected to a Model 760-03 Central Controller

Power: 12 Vdc nominal (9 Vdc minimum), maximum current 35 mA, provided by Model 760-03 Central Controller

Control Data: Type: RS-485

Data Rate/Format: 115.2 kbit/s, 8-N-1

Connector: 9-pin female D-subminiature (DE-9F)

Dimensions (Overall):

3.20 inches wide (8.1 cm)

2.20 inches high (5.6 cm)

4.10 inches deep (10.4 cm)

Weight: 0.8 pounds (0.4 kg)

Speciﬁcations and information contained in this User Guide subject to change without notice.

Mounting: one space (1U) in a standard 19-inch rack

Weight:

3.6 pounds (1.6 kg)

Model 77 Control Console

Application: up to four Model 77 Control Con-

soles can be connected to a Model 760-03 Central Controller

Power: 12 Vdc nominal (9 Vdc minimum), maximum current 100 mA, provided by Model 760-03 Central Controller

Control Data: Type: RS-485

Data Rate/Format: 115.2 kbit/s, 8-N-1

Connector: 9-pin female D-subminiature (DE-9F)

Dimensions (Overall):

7.20 inches wide (18.3 cm)

2.20 inches high (5.6 cm)

5.40 inches deep (13.7 cm)

Weight: 1.7 pounds (0.8 kg)

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Appendix A—Connection Pin-Out Charts

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 ohm

2) Connector type on Model 760-03 is 25-pin female D-subminiature (DB-25F). Installer must provide male (DB-25M). Connector uses 4-40 threaded inserts for locking with mating plug.

3) Wiring scheme follows AES59-2012 convention. Standard TASCAM-type wiring harnesses are directly compatible, with the possible exception of 4-40 screw threads being required.

s, 5 Vpp) compatible.

Connections for Surround A, Surround B, Stereo A, and Stereo B Digital Inputs

Signal Pin Direction

Data Shield 1 Shield

Remote Mute All 5 Input

Remote Dim 6 Input

Remote Spare 1 8 In

Remote Spare 2 9 Input

Remote Input Common 4 Common

Note: Connector type on Model 760-03 is 9-pin female D-subminiature (DE-9F). Connector uses 4-40 threaded inserts for locking with mating plug.

put

Connections for Remote Control Inputs

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

Notes: 1) All signals transformer-coupled digital audio; balanced AES3 (110 ohms, 5 Vpp) compatible.

2) Connector type on Model 760-03 is 25-pin female D-subminiature (DB-25F). Installer must provide male (DB-25M). Connector uses 4-40 threaded inserts for locking with mating plug.

3) Wiring scheme follows AES59-2012 convention. Standard TASCAM-type wiring harnesses are directly compatible, with the possible exception of 4-40 screw threads being required.

Stereo 8 1 14 2

Connections for Digital Monitor Outputs

Signal Signal Connections Channel High (+) Low (–) Shield

Surround L 1 24 12 25

Surround R 2 10 23 11

Surround C 3 21 9 22

Surround SUB 4 7 20 8

Surround LS 5 18 6 19

Surround RS 6 4 17 5

Stereo L 7 15 3 16

Stereo R 8 1 14 2

Notes: 1) Connector type on Model 760-03 is 25-pin female D-subminiature (DB-25M). Connector uses 4-40 threaded inserts for locking with mating plug.

2) Wiring scheme follows AES59-2012 convention. Standard TASCAM-type wiring harnesses are directly compatible, with the possible exception of 4-40 screw threads being required.

(DB-25F). Installer must provide male

Connections for Analog Monitor Outputs

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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 760-03 is 9-pin female D-subminiature (DE-9F). Connector uses 4-40 threaded inserts for locking with mating plug.

Connections between Model 760-03 and Model 77 and Model 71

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Appendix B—Sync Input Sources

The Model 760-03’s sync input has been tested and conﬁrmed for correct operation with the following sync signals:

Word Clock: Square wave signal with rate of 32, 44.1, 48, 88.2, 96, 176.4, or 192 kHz.

DARS (AES11) or AES3: Signal with sample rate of 32, 44.1, 48, 88.2, 96, 176.4, or

192 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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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. 1 = 0 dB; 0.707 = –3 dB; 0.5 = –6 dB;

0.35 = –9 dB; 0 = full attenuation.

Surround to Stereo L = (1 or 0.707)L + (0.707 or 0.5)C + (0.707 or 0.5)LS +(0 or 0.5)LFE R = (1 or 0.707)R + (0.707 or 0.5)C + (0.707 or 0.5)RS + (0 or 0.5)LFE C, LFE, LS, and RS monitor outputs mute

Stereo to Mono With a stereo input selected the result is: C = 0.707L + 0.707R L, R, LS, RS, and LFE monitor outputs mute With a surround input selected the surround to stereo downmix function automatically enables resulting in: C = (0.707 or 0.5)L + (0.707 or 0.5)R + (0.707 or 0.5)C + (0.5 or 0.35)LS + (0.5 or 0.35)RS + (0 or 0.5)LFE

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Studio Technologies 760-03 User Manual V.4.15

Specifications and Main Features

Frequently Asked Questions

User Manual

Table of Contents

Revision History

Introduction

Installation

Operation

Technical Notes

Appendix A—Connection Pin-Out Charts

Appendix B—Sync Input Sources

Appendix C—Downmix Formulas