Data Sheet

Studio Technologies, Inc. StudioComm 780-01/790, Issue 1, Page 2
Two surround (7.1) digital monitor outputs are provided. The pre-fader monitor output can be used with metering systems that
require signals that aren’t impacted by level control or other monitoring functions. The post-fader monitor output is intended
for connection to the inputs on a monitor loudspeaker system. Both the pre- and post-fader monitor outputs are compatible
with equipment that requires balanced AES3 digital audio signals with an output impedance of 110 ohms and a signal level of
5 volts peak-to-peak (Vpp).
A sophisticated bass management function is integral to the Model 780-01’s design and can be enabled if desired. The overall goal
of bass management is very simple: ensure that the entire audio bandwidth of all channels can be accurately monitored. Many
loudspeaker systems have inherent low-frequency limitations, preventing a true sonic “picture” of the source material from being
presented. To overcome this, the low-frequency energy from the seven channels associated with the surround inputs and the two
channels associated with the stereo input can be separated and routed to the subwoofer (SUB) channel of the post-fader monitor
output. 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 was preserved.
All audio processing, including bass management, is performed in 32-bit logic using a high-speed field-programmable gate array
(FPGA) integrated circuit. High-performance integrated circuits are used to perform input,
output, and clocking tasks.
The Model 780-01 occupies one space (1U) in a standard 19-inch rack. Digital audio
sources are interfaced with the Model 780-01 using one 25-pin female D-subminiature
connector and one 3-pin female XLR connector. A BNC connector is used to interface with
an external sync source. Pre- and post-fader digital monitor output signal connections are
made using a 25-pin female D-subminiature connector. One 9-pin female D-subminiature
connector is used to connect the Model 780-01 with a maximum of four Model 790 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 780-01, with
an acceptable range of 100 to 240 V, 50/60 Hz.
Additional Details
The Model 790 provides three buttons and associated LEDs for selection of the source to be monitored. The choices are the two
surround inputs and the stereo input; only one source can be monitored at a time. It’s interesting to note that while the sur-
round inputs have an LFE channel associated with them, the corresponding post-fader monitor output channel is designated
as subwoofer (SUB), rather than LFE. This terminology was 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 chan-
nels, combine it with the contents from the LFE input channel, and route the combination to the post-fader monitor output’s
subwoofer (SUB) channel.
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.
The post-fader 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 monitor output channels
to automatically mute whenever the output level control reaches maximum attenuation. Using the reference level function, the
post-fader 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 user confirmation, the 4-digit LED display will show the level of the post-fader monitor output chan
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nels. To match the needs of a facility, the display can be configured to show either the attenuation level or the sound pressure
level (SPL).
Model 780-01 Central Controller Back Panel
Model 71 Control Console