Data Sheet

Studio Technologies, Inc. StudioComm 76D/77, Issue 4, Page 2
A range of surround (5.1) and stereo digital monitor outputs are provided. The post-fader surround and stereo monitor outputs
are intended for connection to monitor loudspeaker systems. The pre-fader surround 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 monitor
output allows an installation to directly access the SRC capabilities.
For installation flexibility the monitor outputs can be configured for compatibility with equipment that requires balanced or
unbalanced AES3 digital audio signals. When selected for balanced AES3 compatibility the output impedance is 110 ohms with
a signal level of 5 volts peak-to-peak (Vpp). For unbalanced AES3 operation the impedance is 75 ohms and the level is 1 Vpp.
A sophisticated bass management function is integral to the Model 76D’s design and can be enabled if desired. 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 loud
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speaker 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 five surround and two stereo channels can be separated and then routed to
the subwoofer loudspeaker. 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 manage
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ment, is performed in 32 bits using a high-speed field-programmable gate array (FPGA)
integrated circuit.
The Model 76D occupies one space (1U) in a standard 19-inch rack. Digital audio sources
are interfaced with the Model 76D using nine BNC connectors. A tenth BNC connector is
used by the sync source. Digital monitor output signal connections are made using a 25-pin
D-subminiature connector. One 9-pin D-subminiature connector is used to connect the
Model 76D with up to four Model 77 or Model 71 Control Consoles. A second 9-pin “D-sub”
connector is used to interface with remote control signals. AC mains power is connected
directly to the Model 76D, with an acceptable range of 100 to 230 volts, 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 monitor-
ing 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 sur
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round monitor output is 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 main input channels, combing it with the LFE content before routing the sum to the subwoofer
output.
The post-fader surround and stereo 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 attenu
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ation. 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 operator 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).
Model 76D Central Controller Back Panel
Model 71 Control Console