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StudioComm for Surround Sound
As
the production of multi-channel "surround" audio material
becomes prevalent, the need for monitoring these sources becomes
imperative for more and more facilities. Studio Technologies has
addressed this need with the StudioComm for Surround Model 68A Central
Controller and Model 69A Control Console. The system is perfect for a
variety of applications, including adding "5.1" monitoring
capability to disk-based recording systems. It’s also ideal for
upgrading a post-production or broadcast facility to support
multi-channel monitoring. For the first time, multi-channel monitoring
features such as source selection, level control, and downmix are
available in an easy-to-use, cost-effective system.
The
Model 68A/Model 69A combination is expressly designed to support
6-channel (5.1) monitoring, with the channels designated as left,
center, right, left surround, right surround, and LFE. While it is
anticipated that this channel arrangement will be most common, the
channels can obviously used in alternative arrangements.
A
StudioComm for Surround system starts with the Model 69A Control
Console, a compact but comfortable "command center," that is
designed to reside at the operator’s location. Using a single 9-pin
cable, the Model 69A connects to the Model 68A Central Controller. The
Model 68A occupies just one rack space but allows connection of two
multi-channel inputs, two stereo inputs, along with separate 6-channel
and stereo monitor outputs. With the StudioComm for Surround Sound
system any audio console, disk-based recording system, or broadcast
facility can have a complete multi-channel monitor system.
Model
68A Central Controller
The
Model 68A 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.
The
Model 68A provides separate monitor outputs to support both surround
(5.1) and stereo loudspeaker systems. The outputs are electronically
balanced and designed for connection to audio power amplifiers or
amplified loudspeakers. Protection circuitry provides power-up and
power-down protection.
Audio
input and output connections are made using three 25-pin D-subminiature
connectors. The Model 68A’s audio path features analog switches for
input source selection and laser-trimmed voltage-controlled-amplifiers (VCA)
for monitor level control. One 9-pin D-subminiature connector is used to
connect the Model 68A to the Model 69A Control Console. A second 9-pin
"D-sub" connector is used to interface remote control signals
with the Model 68A.
An
8-bit micro-controller provides the logic "horsepower" for the
Model 68A. AC mains power is connected directly to the Model 68A, which
is factory selected for 100, 120, or 220/240 V operation. The internal
power supply utilizes a toroidal mains transformer for quiet audio
operation.
Model
69A Control Console
The
Model 69A 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 major strength of the Model 69A is its ability to
configure, under software control, a number of operating parameters. All
configuration parameters are stored in non-volatile memory.
The
Model 69A 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
surround and stereo monitor output levels 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 allow 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 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.
For
operator convenience, the dim function allows the monitor output level
to be reduced by a fixed dB amount. The dim level is selected 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 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 downmix function is used to create a
stereo signal from a surround (5.1) source. The mono function allows a
stereo signal to be added (summed) and monitored. The downmix and mono
functions can be simultaneously enabled, allowing a surround signal to
be checked for mono compatibility. The mono operating mode 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 mono 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.
The
Model 69A Control Console connects to, and is powered by, the Model 68A
Central Controller using a standard 9-pin D-subminiature cable. The
Model 69A generates MIDI system-exclusive messages to control the Model
68A. Remote-control signals connected to the Model 68A Central
Controller are routed to the Model 69A via pins in the 9-pin
interconnecting cable.
Features
Remote
Control Capability
For
flexibility, the StudioComm for Surround system is designed to easily
integrate with recording consoles, studio communications systems, and film
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.
Limitations
on Signal Routing
While
the StudioComm for Surround system for multi-channel monitoring will do
many wonderful things, it is not designed to selectively route input
signals to the different output channels. The
input-channel-to-output-channel relationship is maintained. A signal that
arrives on the center channel of input 2 will, when selected, output only
on the center 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’s
important to highlight this fact.
Specifications
Model 68A Central Controller
General
Audio:
Frequency Response: 20 Hz-20 kHz ±0.1 dB (down 0.5 dB @ 60 kHz), monitor
outputs
Distortion (THD+N): 0.03%, measured at 1 kHz, +4 dBu, monitor outputs
S/N Ratio: 92 dB, ref +4 dBu out
Crosstalk: 78 dB, ref +4 dBu in
Audio
Inputs: 16, organized as two surround (5.1) and two stereo
(2-channel) inputs
Type: electronically balanced, compatible with balanced or unbalanced
sources
Impedance: 24 k ohms
Nominal Level: –12 dBV to +6 dBu, adjustable
Monitor
Outputs: 2, one surround (5.1), one stereo (2-channel)
Type: electronically balanced, compatible with balanced or unbalanced
loads
Maximum Level: +27 dBu into 10 k ohms, +26 dBu into 600 ohms
Bandpass
Filter:
Response: –3 dB@100 Hz and 5 kHz, nominal, 12 dB/octave
Connectors:
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
Dimensions
(Overall):
19.00 inches wide (48.3 cm)
1.72 inches high (4.4 cm)
8.75 inches deep (22.2 cm)
Mounting:
one space in a standard 19-inch rack
Weight:
8.2 pounds (3.7 kg)
Model 69A Control Console
Application:
supports Model 68A Central Controller
Power:
provided by Model 68A Central Controller
Output
Data: generates MIDI system-exclusive messages
Connector:
1, 9-pin D-subminiature female
Dimensions
(Overall):
7.20 inches wide (18.3 cm)
2.20 inches high (5.6 cm)
5.40 inches deep (13.7 cm)
Weight:
1.9 pounds (0.9 kg)
Specifications
subject to change without notice.
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