Model 74 Central Controller / Model 75 Control Console

Model 74 Central Controller / Model 75 Control Console
Model 74 Central Controller / Model 75 Control Console
StudioComm for Surround
The StudioComm for Surround Model 74 Central Controller and Model 75
Control Console work together to provide 5.1 surround and stereo source
monitoring capabilities, along with a full-featured headphone “talkback”
cue system. The system is a perfect fit for contemporary facilities that need
to perform a variety of audio tasks. These can include surround and stereo
mixing and monitoring, live recording of voice, music, and sound effects,
and on-air broadcast applications. The system’s features were carefully
selected to provide extensive capabilities while remaining simple to operate.
Of overriding concern is maintaining the quality of the connected audio
sources. This is accomplished using a combination of excellent circuit
design and carefully selected components. The Model 74/Model 75 combination is ideal for adding surround monitoring capability to disk-based
recording systems. It’s also well suited for upgrading a post-production or
broadcast facility to support multi-channel monitoring.
Key Features:
Two 5.1 and two stereo inputs
Two 5.1 monitor outputs
Talkback with built-in mic
Up to four Model 35 Talent Amplifiers can
A complete StudioComm for Surround 74/75 system begins with the Model
be connected for headphone monitoring
75 Control Console, a compact user control surface that is intuitive and
• Downmix
comfortable to use. It is designed to reside at the operator’s location. The
• Channel mute/solo
Model 75 connects to the Model 74 Central Controller using a single 9-pin
cable. Occupying one rack space, the Model 74 provides all audio input
and output circuitry, signal routing and control, and power supply functions. To complete the system up to four Model 35 Talent
Amplifier modules can be added. These connect to the Model 74 using standard 3-pin XLR-type audio cables. Model 35 units are
typically deployed in voice-over booths, studio areas, or other locations where voice or music talent needs access to a headphone
cue feed. Each unit provides a stereo audio amplifier, user controls, and support for one or two pairs of headphones.
Model 74 Central Controller
The Model 74 Central Controller is a single rack-space unit that contains analog, digital, and power supply electronics. Four
analog sources can be connected: two surround (5.1) and two stereo. In many applications the first surround input, Surround A,
will be connected to a multi-channel output on an audio console or digital audio workstation. The second surround 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.
The two stereo inputs, Stereo A and Stereo B, are provided for general-purpose use and can be connected to a variety of
2-channel direct and playback sources. For flexibility, the surround and stereo 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.
50220-0106, Issue 1
The Model 74 provides two 6-channel monitor outputs. A powerful system feature is the ability to configure the monitor outputs
to meet the exact needs of an installation. In a “straight-ahead” application the monitor outputs might be configured to support two independent surround (5.1) loudspeaker systems. Alternately, one surround and one stereo monitor system could be
connected. However, other more unique configurations are also possible. These include supporting alternate surround monitor
speaker systems or adding additional LFE or surround speakers. The monitor outputs are electronically balanced and designed
for connection to audio power amplifiers or amplified loudspeakers. Protection circuitry provides power-up and power-down
protection of the connected loudspeaker systems.
Audio input and output connections are made using four 25-pin D-subminiature connectors. The Model 74’s audio path
features low-noise, low-distortion analog switches for input source selection and laser-trimmed voltage-controlled-amplifier
(VCA) integrated circuits for monitor level control. One 9-pin D-subminiature connector is used to connect the Model 74 to the
Model 75 Control Console. A second 9-pin “D-sub” connector is used to interface remote control signals with the Model 74.
The Model 74’s talent amplifier output uses a 3-pin male XLR-type connector. An infrared receiver module can connect to the
Model 74 using a 3.5 mm jack.
An advanced 8-bit microcontroller provides the logic “horsepower” for the Model 74. AC mains power is connected directly to
the Model 74, 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 75 Control Console
The Model 75 Control Console is a compact, self-contained unit designed to be located at the operator’s position. It allows fingertip control of all monitoring and talkback parameters. Numerous LED indicators provide complete status information. A major
strength of the Model 75 is its ability to configure, under software control, many of the operating parameters. All configuration
parameters are stored in nonvolatile memory. The Model 75 Control Console connects to, and is powered by, the Model 74 Central
Controller. The Model 75 generates MIDI system-exclusive messages to control the Model 74. Remote-control signals connected
to the Model 74 Central Controller are routed to the Model 75 via pins in the 9-pin interconnecting cable.
The Model 75 provides four buttons and associated LEDs for selection of the surround and stereo sources to be monitored. While
in most cases only one input source will be monitored at a time, multiple inputs can be selected for simultaneous monitoring.
This allows two, three, or all four of the inputs to be combined (“summed”). While there is no independent control of the input
levels, this feature can be useful for creating rough mixes from the source signals. It is also a fast, effective means of making a
“seat-of-the-pants” check on the phase relationship between synchronized signals.
The monitor output levels are controlled using 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 mute automatically whenever the rotary level control is in
its fully counterclockwise (minimum) position. This is useful in applications such as on-air broadcast. By using the reference
level function, the monitor output level can be set to a pre-configured value. This is provided for audio-with-picture applications
that require a specific monitor level. The reference level is easily configured by taking an electronic “snapshot” of the position
of the rotary level control.
One button controls which monitor output, A or B, is active. For operator convenience, the dim function allows the monitor
output level to be reduced by a fixed dB amount. The dim level is configured from four available levels. A mute all function
allows all of the monitor output channels to be simultaneously muted. The mute/solo section provides individual output channel control. One pushbutton switch sets the operating mode for either mute or solo. In the mute mode, individual channels can
Studio Technologies, Inc.
StudioComm 74/75, Issue 1, Page 2
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 mute and solo
available allows an operator to quickly select the most comfortable and productive operating mode.
Two functions allow the format of the monitored sources to be checked for level or phase inconsistencies. The 5.1 to stereo downmix function is used to create a stereo signal from a 5.1 (surround) source. The stereo to mono downmix function allows a stereo
signal to be added (summed) and monitored. The two downmix functions can be simultaneously enabled, allowing a surround
signal to be checked for mono compatibility. The operating mode of the stereo to mono downmix function can be selected from
two choices: mono-to-left-and-right or mono-to-center. This allows support for both music and audio-with-picture applications.
A bandpass filter feature is associated with the stereo to mono downmix function. It is included to assist an operator in determining compatibility with “real world” playback environments. A bandpass filter can be inserted into the path of the mono signal,
allowing the response of a monaural loudspeaker associated with an inexpensive television or portable radio to be simulated.
To support the headphone cue system functions the Model 75 Control Console includes three pushbutton switches and an
integral microphone. As expected, one button is used to enable the talkback function. The other two buttons are used to set the
talkback level over an 8-step range. These buttons are also used to select which audio source is routed to the headphones. Two
choices are provided: the left and right channels of the source selected for the monitor output, or the left and right channels
associated with Stereo B.
Typically the talkback button contained in the Model 75 will be used to initiate the talkback function. However, some applications may benefit from having remote activation of talkback. The system provides several ways of accomplishing this.
In many cases the talkback button contained in the Model 75 will be used to initiate the talkback function. However, some
applications may benefit from being able to remotely activate talkback. A hard-wired signal can be connected to the remote
talkback input. In this way various types of external wired and wireless equipment can be interfaced. An infrared (IR) receiver
module can also be directly connected. This allows the use of a wireless transmitter to enable talkback. The microphone contained within the Model 75 Control Console provides crisp, clear talkback audio. But some installations may benefit from using
an alternate source of talkback audio. This capability is provided by the Model 74’s line-level talkback audio input.
For flexibility, the system is designed to easily integrate with recording consoles, specialized playback systems, and audio-forpicture machine-control electronics. Four hard-wired remote-control input functions are provided: mute all, dim, talkback,
and input select. 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 remote talkback input allows an externally
provided contact closure or logic signal to control the talkback function. This allows easy integration with additional wired or
wireless talkback devices. The remote input select function is provided expressly for audio 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, referred historically as PEC/direct switching, allows accurate monitoring during dialog replacement, Foley, or
other overdub sessions.
Model 35 Talent Amplifier
In most cases Model 35 Talent Amplifier modules will serve as the user’s headphone
control center. Each Model 35 contains amplifier circuitry, stereo level control,
mono switch, and two output jacks. For convenience, a microphone mounting stand
adapter is included with each Model 35. In addition to the talent amplifier output,
the Model 74 also provides a stereo line-level cue output. This allows interfacing
with other headphone cue systems or could connect to a transmission system associated with a remotely located studio or control
room. The line-level cue output can also serve as a source of “slate” audio for workstations.
Studio Technologies, Inc.
StudioComm 74/75, Issue 1, Page 3
Model 74 Central Controller
General Audio:
Frequency Response: 20 Hz-20 kHz ±0.1 dB (down 0.5 dB @ 60 kHz),
monitor outputs
Distortion (THD+N): 0.04%, measured at 1 kHz, +4 dBu, monitor
S/N Ratio: 87 dB, ref +4 dBu out, 20 Hz-20 kHz, monitor outputs
Crosstalk: 78 dB, typical, ref +4 dBu in, 20 Hz-20 kHz, monitor outputs
Audio: 4, 25-pin D-subminiature female
Talent Amplifier Output: 3-pin male XLR-type
To/From Model 75: 9-pin D-subminiature female
Remote Control Inputs: 9-pin D-subminiature female
Infrared Receiver Input: 3.5 mm 3-conductor jack
AC Mains: 3-blade, IEC 320 C14-compatible (mates with IEC 320 C13)
Audio Inputs: 16, organized as two 6-channel “5.1” inputs and two
2-channel “stereo” 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
AC Mains Requirement:
100, 120, or 220/240 V, ±10%, factory configured, 50/60 Hz, 26 watts
Monitor Outputs: 2, 6-channel
Type: electronically balanced, compatible with balanced or unbalanced
Maximum Level: +27 dBu into 10 k ohms, +26 dBu into 600 ohms
Mounting: one space in a standard 19-inch rack
Talent Amplifier Output:
Compatibility: provides power and audio signals for up to four
Model 35 Talent Amplifiers
Type: DC power with two channels of unbalanced audio
Connections: common on pin 1, DC (+27 volts nominal, 200 milliamperes maximum) modulated with channel 1 audio (–10 dBu nominal)
on pin 2, and channel 2 audio (–10 dBu nominal) on pin 3
Line-Level Cue Output: 1, stereo
Nominal Level: +4 dBu, nominal
Type: electronically balanced, capacitor-coupled, intended to drive
balanced or unbalanced loads of 600 ohms or greater
Source Impedance: 100 ohms, nominal
Maximum Level: +20 dBu into 10 k ohms
Line-Level Talkback Input:
Level: +4 dBu, nominal
Type: electronically balanced
Impedance: 24 k ohms, nominal
Infrared Receiver Input:
Type: intended for use with industry-standard receiver module;
data rate 650 baud
Remote Control Inputs: 4
Type: +5 volts DC logic, activates on closure to system common
Functions: mute, dim, talkback, input select
Dimensions (Overall):
19.00 inches wide (48.3 cm)
1.72 inches high (4.4 cm)
9.58 inches deep (24.3 cm)
Weight: 9.5 pounds (4.3 kg)
Model 75 Control Console
Application: supports Model 74 Central Controller
Power: provided by Model 74 Central Controller
Output Data: generates MIDI system-exclusive messages
Connector: 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: 1.8 pounds (0.82 kg)
Model 35 Talent Amplifier
Load: intended for connection to one or two pairs of headphones with
total impedance of 75 ohms or greater
Maximum Output Voltage: 16 V peak-to-peak into 150 ohms @
1% THD+Noise
Distortion (THD+N): 0.03%
Frequency Response: 20 Hz-20 kHz ±0.5 dB
Dimensions (Overall):
4.2 inches wide (10.7 cm)
2.0 inches high (5.1 cm)
5.3 inches deep (13.5 cm)
Functions: 5.1 to stereo, stereo to mono (mono-to-left-and-right,
5.1 to Stereo: LS @ –3 dB summed with L; RS @ –3 dB summed with
R, C @ –6 dB summed with L and R; LS, RS, and LFE monitor outputs
Stereo to Mono (Mono-to-Left-and-Right): L summed with R to L and R
or L summed with R to C; attenuation independently configurable;
C, LS, RS, and LFE monitor outputs mute
Stereo to Mono (Mono-to-Center): L summed with R to C; attenuation
independently configurable; L, R, LS, RS, and LFE monitor outputs
Weight: 0.8 pounds (0.7 kg)
Stereo to Mono (Mono-to-Center) Bandpass Filter:
Response: –3 dB @ 100 Hz and 5 kHz, nominal, 12 dB/octave
Studio Technologies, Inc.
Specifications subject to change without notice.
Studio Technologies, Inc.
Skokie, Illinois USA
© by Studio Technologies, Inc., January 2006
StudioComm 74/75, Issue 1, Page 4
Model 75 Control Console Front Panel
Monitor Output
Channel Mute / Solo
Mute / Solo
Mode Select
Built-in Microphone
for Talkback
• Stereo to Mono
• 5.1 to Stereo
Monitor Output
• Speaker System
• Reference Level
• Mute All
• Dim
• Rotary Level Control
Input Sources
Model 74 Central Controller Front Panel
Surround Input A
Trim Pots
Surround Input B
Trim Pots
Stereo Input B
Trim Pots
Stereo Input A
Trim Pots
Model 74 Central Controller Back Panel
AC Mains
To / From
Model 75
Output to Infrared Monitor B
Monitor A and
Model 35 Receiver Output and Line-Level Cue
Audio Outputs
Talkback Input
Surround B
and Stereo B
Surround A
and Stereo A
Model 35 Talent Amplifier Front and Back Panels
Headphone Switch between
and Mono
Level Control
(L+R) Output
Studio Technologies, Inc.
To additional
Model 35
Talent Amplifiers
From Model 74
or another
Talent Amplifier’s
Loop Thru Connector
StudioComm 74/75, Issue 1, Page 5
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