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StudioComm for Surround
As
the production of multi-channel "surround sound" audio material becomes
more prevalent, the need to monitor these sources becomes imperative for
more and more facilities. Studio Technologies has addressed the needs of
smaller facilities with the StudioComm Model 68A Central Controller and
Model 69A Control Console. Together they provide a means to select input
sources, control the level of monitor loudspeakers, check format
compatibility, provide mute and solo functions, as well as many other
features.
A
StudioComm for Surround system starts with a Model 68A Central
Controller. The single-rack space Model 68A supports two 6-channel
surround inputs, two stereo inputs, a 6-channel surround monitor output,
and a stereo monitor output. Using a single 9-conductor cable, it
connects to a Model 69A Control Console, a compact but comfortable
"command center" that is designed to reside at the operator's location.
The Models 68A and 69A were developed in conjunction with experts in the
post-production and music audio fields. The overall goal turned out to
be very straightforward: provide the necessary technical performance and
features while keeping it simple to operate, and be certain that
operators won't have to go through a long "learning curve" before they
become efficient. The end result achieves these goals, providing the
required resources in a simple-to-operate format.
Model
68A Central Controller
The
Model 68A Central Controller is a single rack-space unit containing
analog audio and digital control circuitry. Audio input and output
connections are made using three 25-pin D-subminiature ("D-sub")
connectors. The connectors follow the industry-standard multi-channel
wiring scheme. A 9-pin D-sub connector is used to connect the Model 68A
to a Model 69A Control Console. A second 9-pin D-sub connector provides
access to the remote control inputs.
The Model 68A provides
two 6-channel surround and two stereo inputs. Each input circuit uses a
15-turn trim potentiometer to allow operation with nominal signal levels
of –12 dBV to +6 dBu. The 6-channel surround and 2-channel stereo
monitor outputs use electronically balanced circuitry. Electromechanical
relays provide power-up and power-down loudspeaker protection.
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, 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 LEDs provide complete status
information.
The Model 69A provides
four buttons and associated LEDs for selection of the input source 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 level
is controlled either through the use of a large, easy-to-use rotary
control, or by enabling the preset reference level. For operator
convenience, the dim function allows the monitor output level to be
reduced by a fixed dB amount. The mute all function disables all monitor
outputs by activating the mute relays on the Model 68A Central
Controller. A pushbutton switch allows selection of either the 6-channel
surround or the 2-channel stereo monitor output.
Control of the individual
monitor output channels is provided by the mute/solo section. One
pushbutton switch sets the operating mode for either mute or solo. The
flexibility of having both mute and solo available allows an operator to
quickly select the most comfortable and productive operating mode. In
the mute mode, individual channels can be muted or unmuted as required.
In the solo mode, one channel can be monitored while the others are
automatically muted. If desired, multiple channels can be simultaneously
selected for "soloing."
Two functions allow the
format of the monitored signals to be checked for level or phase
inconsistencies. The downmix function is used to create a 2-channel
stereo signal from a surround source. The mono function allows a stereo
signal to be added (summed) and monitored by either the left channel and
right channel monitor outputs, or the center channel monitor output. The
downmix and mono functions can be enabled at the same time, allowing a
surround signal to be checked for mono compatibility.
A bandpass filter can be
inserted into the path of the mono signal when it is being routed to the
center channel. This allows the simulation of the response of a
loudspeaker associated with an inexpensive monaural television or
portable radio.
A
major strength of the Model 69A is the ability to configure, under
software control, many operating parameters. This allows operation to be
tailored to meet the characteristics of an installation. In addition,
the specific operating preferences desired by a facility or individual
user are selected. To meet future needs, all configurations can be
changed at any time. All configuration parameters are stored in
non-volatile memory.
A
Model 69A Control Console connects to the Model 68A Central Controller
using a standard 9-pin D-sub cable. Power for the Model 69A is provided
by the Model 68A. The Model 69A generates MIDI system-exclusive messages
to control the Model 68A. Remote control signals, while physically
connected to the Model 68A, route to the Model 69A via conductors in the
9-pin D-sub interconnecting cable.
Features
Remote
Control Capability
Three remote control
functions are available: mute all, dim, and input select. Remote mute
all and remote dim are provided so that communications systems, machine
control systems, or communication functions associated with audio
consoles can easily be interfaced. Remote input select allows a machine
control system or audio storage device to control which input source is
selected for monitoring. Audio-post professionals will know this as PEC-Direct
switching.
Limitations
on Signal Routing
While the StudioComm Model 68A/Model 69A will do many wonderful things,
it is not designed to selectively route input signals to the different
monitor output channels. A fixed input-channel-to-output-channel
relationship is maintained. A signal on the LFE channel of Surround B
will, when selected, output only on the LFE channel of the monitor
output. Any rerouting of the input signals must be done prior to
connection to the StudioComm system. This should not be an impairment in
most facilities, but it’s important to highlight this fact.
Audio Channel Assignment
The designers of the StudioComm Models 68A and 69A made the decision to
assign the audio channels in the order of left, center, right, left
surround, right surround, and LFE. It was felt that this was a
convenient, rational arrangement, common to many "5.1" installations and
one that would fit the needs of most operators. However, not all formats
follow this convention. Major audio companies such as Dolby Laboratories
and DTS may use different channel assignment schemes in their release
formats. It is hoped that careful interconnection of audio signals
during installation, or incorporating routing flexibility using a patch
bay, will mitigate any significant inconveniences.
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
Line Inputs: 16, organized as two 6-channel inputs and two 2-channel inputs
Type: electronically balanced, direct coupled
Impedance: 24 k ohms
Nominal Level: –12 dBV to +6 dBu
Input Level Control: 15-turn trim potentiometers allow calibration over
–12 dBV to +6 dBu input range
Maximum Input Level: +27 dBu
Common Mode Rejection: 90 dB @ DC and 60 Hz, 85 dB @ 20 kHz, 60 dB @ 400
kHz (typical)
Monitor
Outputs: 6-channel surround, 2-channel stereo
Type: electronically balanced, intended to drive balanced or unbalanced
loads of 600 ohms or greater
Nominal Level: unity gain, audio inputs to monitor outputs
Maximum Output Level—Balanced: +27 dBu into 10 k ohms, +26 dBu into 600 ohms
Maximum Output Level—Unbalanced: +21 dBu into 10 k ohms, +20 dBu into
600 ohms
Output Impedance—Balanced: 50 ohms
Level Control Method: laser-trimmed voltage-controlled-amplifier
integrated circuits manufactured by THAT Corporation
Attenuation Range: 72 dB, nominal, using rotary level control
Bandpass
Filter:
Type: created by cascading (connecting in series) a high-pass and
low-pass filter; each filter 2nd-order (12 dB-per-octave)
Sallen-Key
Response: –3 dB @ 100 Hz and 5 kHz, nominal
Connectors:
Audio: 3, 25-pin D-subminiature female
Control: 2, 9-pin D-subminiature female
AC Mains: 3-blade IEC-type
Remote
Control Inputs: 4, HCMOS-type logic, "pulled up" to +5 Vdc using
10 k ohm resistors, activates on closure to system common
AC
Mains Requirement: 100, 120, or 220/240 V, ±10%, factory configured,
50/60 Hz, 100-120 V 0.4 A maximum, 220/240 V 0.2 A maximum
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:
operates in conjunction with 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.
StudioComm Systems
Which
StudioComm system is right for your application? Review the
StudioComm
Loudspeaker Monitor Control Systems Feature-by-Feature Comparison Chart.
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