StudioComm for Surround Model 78 Central Controller Model 78

StudioComm for Surround Model 78 Central Controller Model 78
Model 78 Central Controller / Model 79 Control Console
StudioComm for Surround
Once exclusively the domain of major motion picture studios and large
production facilities, the recording, mixing, editing, and distribution of
multichannel “surround” audio material has become much more widespread. To handle these tasks, the ability to effectively monitor multichannel sources has become imperative for more and more facilities. Studio
Technologies has addressed this need with the StudioComm for Surround
Model 78 Central Controller and Model 79 Control Console. The system is
perfect for 8-channel “7.1” applications, including adding 7.1 monitoring
capability to disk-based recording systems. It’s also ideal for upgrading a
post-production, mastering, or broadcast facility to support multichannel monitoring. The StudioComm for Surround Model 78 and Model 79
combination is THX® pm3 approved.
The system’s core design goals were audio quality and ease of use. Designed
to support the most sophisticated audio requirements, the signal path was
optimized for sonic quality. The operator features and controls were carefully selected to enhance usability and minimize the learning curve. For
the first time, advanced multichannel monitoring features such as source
selection, level control, downmix, and bass management are available in a
compact, sonically excellent, and cost-effective system.
Key Features:
Two 7.1 surround inputs
One 7.1 surround output
Integrated bass management
Channel mute/solo
Numerous status LEDs
THX® pm3 approved
Model 78 Central Controller
A StudioComm for Surround system starts with the Model 78 Central Controller. Occupying just one rack space, it allows connection of two 8-channel inputs and an 8-channel monitor output. The Model 79 Control Console is a compact, comfortable
“command center” designed to reside at the operator’s location. With the StudioComm for Surround system any audio console,
disk-based recording system, or broadcast facility can have a complete 7.1 multichannel monitor system.
The Model 78 Central Controller is a single rack-space unit that contains analog, digital, and power supply electronics. Two
8-channel analog sources can be connected. In many applications the first input, Surround A, will be connected to a multichannel
output on an audio console or digital audio workstation. The second input, Surround B, will be connected to a playback device,
such as a multitrack tape recorder or disk storage system. For film or video post applications Surround A would be considered
the direct source, while Surround B would be considered the playback source. For flexibility, the inputs are compatible with
balanced or unbalanced signals having a nominal level range of –12 dBV to +6 dBu. Fifteen-turn trim potentiometers are used
to precisely calibrate the input signals.
50094-1003, Issue 2
A sophisticated bass management function is integral to the Model 78’s design. The overall goal of bass management is very
simple: to 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 low-frequency energy from the seven main channels can be separated and then routed to the subwoofer loudspeaker. A
general-purpose bass management configuration is implemented from the factory. In most cases this will provide highly effective
monitoring. To support specialized applications a technician can revise many of the bass management parameters, including
disabling bass management entirely.
The Model 78 provides an 8-channel monitor output to connect to the loudspeaker system. The outputs are electronically
balanced and designed for connection to audio power amplifiers or amplified loudspeakers. Protection circuitry provides powerup and power-down protection. Note that while each of the two surround inputs has an LFE channel associated with it, the
monitor output designates a subwoofer, rather than an LFE output. This terminology was carefully selected to highlight the fact
that the output channel designated for connection to the subwoofer loudspeaker may have more than just LFE content. The bass
management function redirects low-frequency energy from the main channels, combines it with the LFE content, then routes
the sum to the subwoofer output.
Audio input and output connections are made using three 25-pin D-subminiature connectors. The Model 78’s audio path features analog switches for input source selection and digitally controlled analog gain circuits for monitor level control. One 9-pin
D-subminiature connector is used to connect the Model 78 to the Model 79 Control Console. A second 9-pin “D-sub” connector
is used to interface remote control signals with the Model 78. An 8-bit microcontroller provides the logic “horsepower” for the
Model 78. AC mains power is connected directly to the Model 78, which is factory selected for 100, 120, or 220/240 V operation.
The internal power supply utilizes two toroidal mains transformers for quiet audio operation.
Model 79 Control Console
The Model 79 Control Console is a compact self-contained unit designed to be located at the operator’s position. It allows
fingertip control of all monitoring parameters. Numerous LED indicators provide complete status information. A 4-digit numeric
display indicates the monitor output level in real time. A major strength of the Model 79 is its ability to configure, under software
control, a number of operating parameters. For example, during the installation and calibration process, the relative levels of the
monitor output channels can be adjusted. This helps to ensure that maximum performance from the loudspeaker system can be
easily obtained. All configuration parameters are stored in nonvolatile memory.
The Model 79 provides two buttons and associated LEDs for selection of the surround source to be monitored. While in most
cases only one input source will be monitored at a time, both inputs can be selected for simultaneous monitoring. This feature
can be useful, allowing the creation of a rough mix of the two sources. It is also a fast, effective means of making a “seat-of-thepants” check on the phase relationship between synchronized signals. For compatibility with some cinema formats the two input
buttons also allow +10 dB of gain to be added to each input’s LFE channel.
Four downmix modes allow the selected source to be checked for compatibility among different formats. The downmix functions, 5.1, LCRS, Stereo, and Mono, were implemented primarily for use in sound-for-picture applications. As such, from the
factory the downmix coefficients were selected to be effective in these environments. However, a technician can easily change
each downmix mode to meet the specific needs of a facility or audio format.
An LFE low-pass filter function is provided as a means of checking the audio content in the selected input’s LFE channel. The
operator 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 mix content is critical as the LFE channel is often band-restricted during distribution.
Studio Technologies, Inc.
StudioComm 78/79, Issue 2, Page 2
The monitor output level can be controlled by way of a large, easy-to-use rotary control. The “curve” or “taper” of the level control
can be configured to match an operator’s preference. The choices available are true logarithmic and modified logarithmic. The
level control auto mute-all function allows the monitor output channels to automatically mute whenever the rotary level control
is in its fully counterclockwise (minimum) position. This is useful in applications such as broadcast. By using the reference
level function, the monitor output level can set to a preconfigured value. This is provided for applications that require a specific
monitor level to be quickly selected. The reference level is easily configured by taking an electronic “snapshot” of the position
of the rotary level control. For operator confirmation, the 4-digit LED readout displays the level of the monitor output.
For operator convenience, the dim function allows the monitor output level to be reduced by a fixed dB amount. The mute-all
function allows one button to simultaneously mute all eight monitor output channels. The input mute/solo section provides
individual input channel control. One push-button switch sets the operating mode for either mute or solo. In the mute mode,
individual input channels can be muted as required. In the solo mode, one channel can be monitored while the others are automatically muted. Depending on the configuration, multiple channels can be simultaneously selected for “soloing.” The flexibility
of having both input mute and input solo available allows an operator to quickly select the most comfortable and productive
operating mode.
Two output mute functions are also provided. One button allows the seven main output channels to be directly muted. A second
button allows the subwoofer monitor output channel to be muted. The output mute function, along with the input mute/solo
function, allows an operator complete flexibility when checking an input source and its path to the loudspeaker system. These
mute and solo resources are crucial in a multichannel environment, especially when signals are passing through the integrated
bass management system.
The Model 79 Control Console connects to, and is powered by, the Model 78 Central Controller. The Model 79 generates MIDI
system-exclusive messages to control the Model 78. Remote-control signals connected to the Model 78 Central Controller are
routed to the Model 79 via pins in the interconnecting cable.
Remote Control Capability
For flexibility, the StudioComm for Surround system is designed to easily integrate with recording consoles, studio communications systems, and film or video motion-control electronics. Three remote-control input functions are provided: mute all, dim,
and input source override. By providing access to the StudioComm’s mute all and dim functions, talkback or slate activity from
an audio console or other communications system can control the monitor output level. The input source override function is
provided expressly for film post applications, allowing automatic switching of the StudioComm’s input source whenever the
mode of a recording system changes between playback and record. This function, often referred to as PEC/direct switching,
allows accurate monitoring during dialog replacement or other overdub sessions.
Channel Assignment and Routing
The Model 78/Model 79 combination is expressly designed to support 8-channel 7.1 monitoring, with the input channels designated as left, right, center, LFE, surround left, surround right, back left, and back right. While it is anticipated that this channel
arrangement will be quite common, the channels can obviously be used in alternative arrangements. Using the system with 5.1
sources is also perfectly acceptable.
While the StudioComm for Surround system for multichannel monitoring will do many wonderful things, it is not designed to
selectively route input signals to different output channels. The input-channel-to-output-channel relationship is maintained. A
signal that arrives on the SL channel of the Surround B input will, when selected, output only on the SL channel of the monitor
output. Any rerouting of the input signals must be done prior to their connection to the StudioComm for Surround system. This
should not be a drawback in most facilities, but it is important to highlight this fact.
Studio Technologies, Inc.
Skokie, Illinois USA
+1 847-676-9177
© by Studio Technologies, Inc., October 2003
Studio Technologies, Inc.
StudioComm 78/79, Issue 2, Page 3
Model 78 Central Controller
General Audio:
Frequency Response: 20 Hz-20 kHz ±0.2 dB (down 0.5 dB @ 80 kHz),
monitor outputs
Distortion (THD+N): 0.004%, measured at 1 kHz, +4 dBu, monitor
S/N Ratio: 90 dB, ref +4 dBu out, 20 Hz-20 kHz, monitor outputs
Crosstalk: 80 dB, typical, ref +4 dBu in, 20 Hz-20 kHz, monitor outputs
Audio Inputs: 16, organized as two 8-channel “7.1” inputs
Type: electronically balanced, compatible with balanced or unbalanced
Impedance: 24 k ohms
Nominal Level: –12 dBV to +6 dBu, adjustable
Level Calibration: 15-turn trim potentiometers
Monitor Outputs: 1, 8-channel “7.1”
Type: electronically balanced, compatible with balanced or unbalanced
Maximum Level: +27 dBu into 10 k ohms, +26 dBu into 600 ohms
Main Input Channel High-Pass Filters: 7
Type: 2nd order Sallen-Key; factory configured for 12 dB/octave; field
configurable for flat or 12 dB/octave response
Response: –3 dB @ 80 Hz, nominal, 12 dB/octave; field configurable
Main Input Channel Low-Pass Filters: 7
Type: 2nd order Sallen-Key; 12 dB/octave; field configurable for
disabled or 12 dB/octave response
Response: –3 dB @ 80 Hz, nominal, 12 dB/octave; field configurable
Secondary Input Channel Low-Pass Filter:
Type: 2nd order Sallen-Key; 12 dB/octave
Response: –3 dB @ 80 Hz, nominal, 12 dB/octave; field configurable
LFE Input Channel to Subwoofer Output:
Overall Gain: 0 or +10 dB, nominal, switch selectable
LFE Input Channel Low-Pass Filter:
Type: four cascaded 2nd order Sallen-Key sections; 48 dB/octave
(8th order)
Response: –6 dB @ 120 Hz, nominal, field configurable
Operation: switch selectable, on/off
Audio: 3, 25-pin D-subminiature female
Control: 2, 9-pin D-subminiature female
AC Mains: 3-blade IEC-type
Remote Control Inputs: 3
Type: +5 V logic, activates on closure to system common
AC Mains Requirement: 100, 120, or 220/240 V, ±10%, factory
configured, 50/60 Hz, 30 VA
Dimensions (Overall):
19.00 inches wide (48.3 cm)
1.72 inches high (4.4 cm)
9.58 inches deep (24.3 cm)
Mounting: one space in a standard 19-inch rack
Weight: 9.5 pounds (4.3 kg)
Model 79 Control Console
Application: supports Model 78 Central Controller
Power: provided by Model 78 Central Controller
Output Data: generates MIDI system-exclusive messages
Connector: 1, 9-pin D-subminiature female
Dimensions (Overall):
7.2 inches wide (18.3 cm)
2.2 inches high (5.6 cm)
5.4 inches deep (13.7 cm)
Weight: 1.9 pounds (0.9 kg)
Specifications subject to change without notice.
Studio Technologies, Inc.
THX pm3 approved
THX and pm3 are trademarks or registered trademarks of THX Ltd. All rights reserved.
Studio Technologies, Inc.
Skokie, Illinois USA
+1 847-676-9177
© by Studio Technologies, Inc., October 2003
StudioComm 78/79, Issue 2, Page 4
Input Mute / Solo
Mute / Solo
Mode Select
Main / Sub
Output Mute
Input Sources
Monitor Output
Level Display
Monitor Output
• LFE Low-pass Filter
• Reference Level
• Mute All
• Dim
• Rotary Level Control
Model 79 Control Console Front Panel
Model 78 Central Controller Front Panel
Surround A
Trim Pots
Surround B
Trim Pots
Model 78 Central Controller Back Panel
AC Mains
To / From
Model 79
L, R, C, Sub,
Monitor Output
Input Surround B
Input Surround A
Studio Technologies, Inc.
StudioComm 78/79, Issue 2, Page 5
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