Studio Technologies 74, 75 Data Sheet
from
Model 74
&
Model 75
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 fullfeatured headphone “talkback” cue system. The system is a perfect fi t 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 eff ects, 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.
Monitor output
channel mute
Mute / solo
mode select
Downmix
• Stereo to Mono
• 5.1 to Stereo
/ solo
Input sources
Model 74 Central Controller Front Panel
Surround Input A
trim pots
Surround Input B
trim pots
Stereo Input A
trim pots
Stereo Input B
trim pots
Talkback
functions
Model 74 Control Console Front Panel
Monitor output
• Speaker system
• Reference level
• Mute all
• Dim
• Rotary level control
Data
Powe r
active
present
LED
LED
50220-0106, Issue 1
Overview
A complete StudioComm for Surround 74/75 system begins with the Model 75 Control Console, a
compact user control surface that is intuitive and comfortable to use. It is designed to reside at the
operator’s location. The 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
Amplifi er 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
amplifi er, user controls, and support for one or two pairs of headphones.
Model 74
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 fi rst 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 fi lm 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 fl exibility, the surround and stereo
inputs are compatible with balanced or unbalanced signals having a nominal level range of –12 dBV
to +6 dBu. Fi een-turn trim potentiometers are used to precisely calibrate the input signals.
The Model 74 provides two 6-channel monitor outputs. A powerful system feature is the ability
to confi gure the monitor outputs to meet the exact needs of an installation. In a “straight-ahead”
application the monitor outputs might be confi gured to support two independent surround (5.1)
loudspeaker systems. Alternately, one surround and one stereo monitor system could be connected.
However, other more unique confi gurations 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 amplifi ers or amplifi ed
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-amplifi er (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 amplifi er 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.
Model 74 Central Controller Back Panel
AC mains
input
connection
Studio Technologies, Inc. Model 74 & Model 75, Issue 1, Page 2
To/from
Model 75
Control
Console
Remote
control
inputs
Output to
Model 35
Talent
Amplifiers
Infrared
receiver
input
Monitor B
output and
line-level
talkback input
Monitor A and
line-level cue
audio outputs
Surround B and
stereo B inputs
Surround A and
stereo A inputs
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