for Surround Model 780-01 Central Controller and Model 790 Control Console User Guide Issue 4, December 2020 This User Guide is applicable for systems consisting of: Model 780-01: serial number M780-01-00151 and later with software version 1.00 and higher and FPGA version 4.15 and higher; Model 790: serial number M790-00151 and later with software version 1.00 and higher © 2020 by Studio Technologies, Inc., all rights reserved www.studio-tech.
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for Surround Table of Contents Revision History ........................................................... 4 Introduction ................................................................... 5 Installation .................................................................... 9 Configuration ................................................................16 Operation ......................................................................35 Technical Notes ......................................................
for Surround Revision History Issue 4, December 2020: • Revised how dim values are stated. Now are four positive dB values. Operation does not change. For clarification only. Issue 3, October 2016: • Revised text for error codes Err1, Err2, and Err3; added text for error code Err4. Issue 2, April 2015: • Revised specifications to reflect final audio performance measurements. • Text clarifications. Issue 1, January 2015: • Initial release.
for Surround Introduction What This User Guide Covers This User Guide is designed to assist you when installing and using the Model 780-01 Central Controller and one or more associated Model 790 or Model 71 Control Consoles. Overview Creating and distributing eight channel (7.1) surround audio material has become common for entertainment, cinema, and allied applications. As such, the ability to simply and effectively monitor these sources is imperative during the recording and post-production process.
for Surround delays (latency) associated with associated video displays up to 340 milliseconds of input delay can be selected. For flexibility, two delay values can be configured, allowing real-time selection as desired. A number of different signals can serve as the Model 780-01’s digital audio timing reference. For synchronization with a master timing reference a dedicated source of word clock, DARS (AES11), bi-level video, or tri-level video can be connected.
for Surround Channel mute/solo Mute/solo mode Downmix Input source select Monitor output level display Post-fader surround monitor output • Surround/stereo • Reference level • Mute all • Dim • Rotary level control Figure 3. Model 790 Control Console Front Panel Great care was taken in designing the system’s architecture, ensuring that the character of the audio input signals was preserved.
for Surround An LFE low-pass filter function is provided as a means of checking the audio content in the LFE channel of a selected surround input. The user can enable and disable the function as required, helping to ensure that the proper signals are being mixed to the LFE channel. Having the correct audio content in the LFE channel can be critical as the LFE channel is typically band-restricted during distribution.
for Surround Installation In this section you will be installing the Model 780-01 Central Controller in an equipment rack. Connections to the surround and stereo audio inputs and preand post-fader surround monitor outputs will be made. A dedicated digital audio timing reference signal can be connected to the sync input. If desired, external equipment will be interfaced to the remote control inputs.
for Surround There is, however, an exception worth noting. Circuitry associated with the stereo input has sample rate conversion (SRC) capability, allowing virtually any stereo digital audio signal to be connected. A signal connected to the stereo input can have an independent sample rate and timing reference while still being monitored correctly. Refer to the Technical Notes section of this user guide for a detailed review of the SRC capability.
for Surround and the other post-fader (level adjustable by the user). The pre-fader monitor output channels are intended for connection to metering or monitoring equipment that requires uninterrupted full-level signals. The post-fader monitor output channels are intended to be connected to a loudspeaker system that provides seven main channels and one subwoofer channel.
for Surround be connected to the inputs of loudspeakers that contain integrated amplifiers with digital audio input capability. Sync Input The Model 780-01 requires a timing reference (sync) source so that the audio input and monitor output signals will be interpreted correctly. A configuration setting allows the source of sync to be selected. The default setting uses the L/R input of the currently selected input source which can be either of the surround inputs or the stereo input.
for Surround Inputs of this type are commonly referred to as GPI inputs. While the input circuitry is protected from over-current and static discharge (ESD), care should be taken to prevent nasty signals from reaching them. The inputs are active only when held in the low state; they can’t be configured to change state (“latch”) in response to a logic pulse. A 9-pin D-subminiature connector (DE-9F) is used for the remote control inputs. Refer to Figure 6 or Appendix A for connection details.
for Surround implementation has the advantages of providing a shield for the data path and a more robust common (return path) connection (two conductors including the shield) for the DC power circuit. A few simple calculations are required to determine the maximum cable length when fabricating a cable to be used when connecting a Model 780-01 to a Model 790.
for Surround AC Mains Power The Model 780-01 operates directly from AC mains power over a range of 100 to 240 V, 50/60 Hz. Being a “universal input” device, there are no switches to set or jumpers to install to match a location’s mains voltage. The unit uses a 3-pin IEC 320 C14-type inlet connector to mate with a detachable mains cord. All units are supplied with a mains cord that has a NorthAmerican-standard plug (NEMA 5-15L) on one end and an IEC 320 C13 socket on the other.
for Surround Only after the Model 780-01 and all connected Model 790 and Model 71 units have correctly powered up will full system operation begin. Configuration After the physical installation has been completed it’s important that the system’s configuration options be carefully reviewed. In most cases one or more of the operating parameters will be revised to meet the needs of the specific installation.
for Surround As a user aid, a Model 790 that has entered the configuration mode will have its mode mute and mode solo LEDs (associated with the input mute/solo section) light in an alternating manner. Other connected Model 790 units will indicate that they have entered the standby mode by simultaneously flashing their mode mute and mode solo LEDs. To leave the configuration mode and return the system to normal operation requires a final action to be made.
for Surround there might be cases where this resource isn’t desired and it can be disabled. Bass Management The Model 780-01 incorporates flexible and sonically excellent bass management capabilities. One configuration parameter is used to enable or disable bass management while three others are used to select the characteristics of the associated audio filters. While the settings are simple to make, great care must be taken to first review the entire monitor system.
for Surround level to be stored and then enabled by pressing the Model 790 button labeled Reference Level. Setting the reference level is very simple but care is required: 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. 1. Set up a precision sound pressure level (SPL) measuring device at the desired listening location. 7. To complete the process the configuration mode must be exited.
for Surround will show negative values, reaching –70.0 before the full mute function automatically mutes the post-fader monitor outputs. In the SPL mode the display can be configured to allow the output level to be presented to users in terms of an actual sound pressure level (SPL). It is used in conjunction with the reference level in dB SPL configuration and the stored reference level. The SPL mode allows a user to see a visual representation of the SPL level that is present in the listening environment.
for Surround when the To Stereo downmix function is active, LFE is reduced in level by 6 dB and routed to both the left (L) and right (R) postfader monitor outputs. When in this mode and the To Mono downmix function is active the level of the LFE channel is reduced by 6 dB and routed to the center (C) post-fader monitor output. Pre-Fader Monitor Output Mode The pre-fader monitor output can be configured as to its place in the Model 780-01’s signal flow. The choices are pre- or postdownmix.
for Surround one channel should serve as the overall reference level and not be changed. This is typically the center channel. This feature is provided primarily for use when the post-fader monitor output channels are connected to loudspeaker systems that don’t offer a means of “trimming” the input sensitivity of individual channels. Without this capability, minor adjustments to the output level of specific loudspeakers to account for room acoustics wouldn’t be possible.
for Surround Device Address The dim and reference level LEDs will display the Model 71’s device address. The rotary level control is used to select the desired device address; the LEDs will respond accordingly. The device address must be selected so as not to conflict with the device address of any other connected Model 71 or Model 790 Control Console. The choices are A1, A2, A3, and A4. All Model 71 units have a default device address of A4; Model 790’s units have a default device address of A1.
for Surround Configuration—Entering and Exiting Configuration Mode and hold the configuration Press button for 2 seconds to enter or exit the configuration mode. These LEDs will light alternately when configuration mode is ac- Issue 4, December 2020 Page 24 Model 780-01/790 User Guide Studio Technologies, Inc.
for Surround Configuration—Model 790 Device Address and Stereo Input Sample Rate Converter Press and hold the Mute/Solo button to display and configure the Model 790’s device address and stereo input sample rate converter. This LED displays the configuration of the stereo input sample rate converter (SRC). LED L not lit means SRC is disabled; LED L lit means SRC enabled. Use the button to change the configuration. Use the Level control to change this specific Model 790’s device address.
for Surround Configuration—Bass Management This LED displays the status of the bass management function. LED LFE lit means bass management enabled; LED LFE not lit means bass management disabled. Use the button to change the configuration. Use these buttons to select bass management low-pass filter slope. LED Surround A lit means 24 dB-per-octave; LED Surround B lit means 12 dB-per-octave. Use these buttons to select bass management highpass filter slope. LED To 5.
for Surround Configuration—Sync Source, Sync Input Termination, and Audio-Synced-to-Video Sample Rate This LED displays the configuration of the sync input termination. LED L not lit means sync input is not terminated; LED L lit means terminated with 75 ohms. Use the button to change the configuration. Use these buttons to select the sync source: Video DARS Press and hold the Mains button to display and select the sync source, sync input termination, and audio-syncedto-video-sample rate.
for Surround Configuration—Reference Level and hold the Reference Level button for 5 seconds to take a “snapshot” Press of the level control’s setting at the time configuration mode was entered. The Reference Level LED will flash when the button is initially pressed and then light steadily when the “snapshot” has been taken. See Note below. Default: Reference level set for –60.0 dB post-fader monitor output level.
for Surround Configuration—Overall Display Mode, Reference Level in dB SPL, and Auto Reference Level Off When the Mute All button is pressed, use the Channel Mute/Solo L and R buttons to select the overall display mode. LED L lit means attenuation mode is selected; LED R lit means SPL mode is selected. Use the buttons to change the configuration. When the Mute All button is pressed, use the Reference Level button to enable or disable auto reference level off.
for Surround Configuration—Dim Level, Remote Mute All, and Remote Dim This LED displays the configuration of remote mute all. LED L not lit means remote mute all is disabled; LED L lit means enabled. Use the button to change the configuration. This LED displays the configuration of remote dim. LED C not lit means remote dim is disabled; LED C lit means enabled. Use the button to change the configuration.
for Surround Configuration—LFE Downmix Level and Pre-Fader Monitor Output Mode These LEDs display the configuration of the prefader monitor output mode. LED L lit means output channels are pre-downmix; LED R lit means output channels are post-downmix. Use the buttons to change the configuration. Default: Use this button to select the LFE downmix level when the To Stereo or To Mono downmix functions are active. LED LFE not lit means full attenuation; LED LFE lit means –6 dB.
for Surround Configuration—Input Delay Settings Press and hold the Stereo button to display and select input delay A. Press and hold the To 5.1 button to display and select input delay B. Use the level control to adjust the input delay. Range is from 0 to 340. The display shows delay in milliseconds at 48 kHz sampling rate. The value is scaled up or down for other sample rates. Default: Input delay 0 milliseconds for both A and B.
for Surround Configuration—Post-Fader Monitor Output Level Offsets Press and hold the R button to configure the surround R level offset. Press and hold the C button to configure the surround C level offset. Press and hold the LFE button to configure the SUB level offset. Press and hold the SL button to configure the surround SL level offset. Press and hold the SR button to configure the surround SR level offset. Press and hold the BL button to configure the surround BL level offset.
for Surround Configuration—Restore Factory Defaults and hold both the LFE Low-Pass and Dim buttons for 5 seconds to Press restore Model 780-01 and Model 790 factory defaults. Once defaults have been restored, the associated LEDs will light. After the buttons are released, configuration mode will be exited and normal operation will resume. See Note below. Factory Defaults: Device address A1. Stereo input sample rate converter enabled. Bass management disabled.
for Surround Operation Control Consoles Upon AC mains power up the system will return to the last operating condition, including the selected source, downmix mode, etc. As a precaution, however, the post-fader monitor output level will always return to the minimum value. The rotary level control or the reference level button must then be used to set the level of the post-fader monitor output to the desired level.
for Surround surround source to be “folded down” (mixed) to stereo. The resulting signal is reproduced on the left (L) and right (R) monitor output channels. The To Mono function allows a 7.1 surround or stereo source to be converted to a single monaural channel. The resulting signal is reproduced on the center (C) monitor output channel. Using the downmix functions simply requires pressing the desired button. The buttons are set to always “latch” the functions on and off.
for Surround mute all is active. Note that if mute all is enabled via the remote mute all function, the mute all LED will flash. Dim The dim function is provided for user convenience, allowing the post-fader monitor output level to be reduced by a fixed amount. The Model 790’s configuration mode allows the dim level to be selected from among four choices: 10, 15, 20, or 25 dB. Pressing the dim button will enable the function. The dim button is always set to “latch” the function on and off.
for Surround Displaying the Current Sample Rate The LFE low-pass filter button is also used to display the system’s current sample rate value. Pressing and holding the LFE lowpass button will cause the current sample rate value to be shown on the 4-digit display. The possible values displayed will be 44.1, 48.0, 88.2, or 96.0. This can be useful during troubleshooting or just for general interest. Once the button is released normal display operation will resume.
for Surround The output mute function organizes the monitor output channels into two groups: the main channels (mains) and the subwoofer (SUB). The mains group consists of the seven main output channels: left (L), right (R), center (C), surround left (SL), surround right (SR), back left (BL), and back right (BR). The SUB group consists of only the subwoofer (SUB) output channel. Two buttons and associated LEDs are used to control the output mute function. Both buttons function in a push-on/push-off manner.
for Surround During normal operation, press and hold the Mute/Solo button to view and change the input delay setting. This LED displays the current setting of the input delay. LED not lit means input delay A is selected; LED lit means input delay B is selected. Press the button to change the setting. The display shows the currently selected input delay in milliseconds. Figure 10. Selecting the input delay 4-digit display will always show the output level in positive numbers.
for Surround allows adjustment of the post-fader monitor output level. Two buttons, along with associated LEDs, provide access to the dim and reference level functions. A status LED lights steadily whenever normal Model 71 operation is taking place. Any changes made using the Model 71’s rotary level control and buttons will be reflected in the appropriate LEDs and displays on all the connected Model 790 and Model 71 units.
for Surround flash. On all connected Model 790 Control Consoles the 4-digit LED display will cease normal operation, instead alternating between the words no and sync. When a valid sync signal is again connected the Model 780-01’s sync status LED will light steadily. On the Model 790 units the word sync will momentarily be displayed followed by a brief display of the active sample rate. The sample rate will display as 44.1, 48.0, 88.2, or 96.
for Surround Error Code Err2 Err2 indicates that the Model 780-01 is having problems with its internal logic device. (A high-speed field-programmable gate array (FPGA) serves as the digital “heart” of the Model 780-01 and without it no audio activity can occur.) The only way to remedy this condition is to first try removing and reconnecting mains power. (And that’s a long-shot as to whether it would accomplish anything.
for Surround normally connected input signals will be “locked” to a main timing reference signal that supports the 48 kHz sampling rate. But, as an example, a signal associated with a portable device, while at a 48 kHz sampling rate, may not be synchronized (“genlocked”) to the “house” reference. Connecting this signal to the stereo input will cause the SRC function to “lock” it to the Model 780-01’s rate, thus allowing it to be monitored over a loudspeaker system.
for Surround Specifications Model 780-01 Central Controller General Audio: Supported Sample Rates: 44.1, 48, 88.2, and 96 kHz Word Length: 24 bits maximum Internal Processing: 32 bits Input-to-Output Latency: two samples (e.g., 0.042 milliseconds @ 48 kHz sample rate) Digital Audio Inputs: 3 (18 audio channels total) Configuration: two surround (7.
for Surround Model 790 Control Console Model 71 Control Console Application: up to four Model 790 Control Consoles can be connected to a Model 780-01 Central Controller Application: up to three Model 71 Control Consoles can be connected to a Model 780-01 Central Controller Power: 12 Vdc nominal (9 Vdc minimum), maximum current 100 mA, provided by Model 780-01 Central Controller Power: 12 Vdc nominal (9 Vdc minimum), maximum current 35 mA, provided by Model 780-01 Central Controller Control Data: Type
for Surround Appendix A—Connection Pin-Out Charts Channel Signal High (+) Signal Low (–) Shield Connections Channel Signal High (+) Signal Low (–) Shield Surround Input A L/R 1 24 12 25 Pre-Fader L/R 1 24 12 25 Surround Input A C/LFE 2 10 23 11 Pre-Fader C/SUB 2 10 23 11 22 Connections Surround Input A SL/SR 3 21 9 22 Pre-Fader SL/SR 3 21 9 Surround Input A BL/BR 4 7 20 8 Pre-Fader BL/BR 4 7 20 8 Surround Input B L/R 5 18 6 19 Post-Fader L/R 5 18 6
for Surround Appendix B—Sync Input Sources The Model 780-01’s sync input has been tested and confirmed for correct operation with the following sync signals: Word Clock: Square wave signal with rate of 44.1, 48, 88.2, or 96 kHz. DARS (AES11) or AES3: Signal with sample rate of 44.1, 48, 88.2, or 96 kHz. Bi-Level and Tri-Level Video: See table below. Video Format Video Format, continued NTSC (“Black Burst”) 1035i/59.98 Hz PAL (“Black Burst”) 1035i/60 Hz 525i/59.94 Hz 1080i/50 Hz 525p/59.
for Surround Appendix C—Downmix Formulas The following provides a summary of the action performed when the downmix modes are active. Signals at unity gain unless noted. 0.707 = –3 dB; 0.5 = –6 dB; 0 = full attenuation. To 5.1 SL = SL + BL SR = SR + BR BL and BR mute To Stereo L = L + 0.707C + 0.707SL + 0.707BL + (0 or 0.5)LFE R = R + 0.707C + 0.707SR + 0.707BR + (0 or 0.5)LFE C, LFE, SL, SR, BL, and BR mute To Mono For Surround Input A, Surround Input B C = .707L + .707R + C + 0.5SL + 0.5SR + 0.5BL + 0.
