Oxmoor DCA-2 - Manual (Page 3)

Page 1
DCA-2 & RC-16 INTRODUCTION
The Oxmoor DCA-2 Digital Control Attenuator and one
or more RC-16 Remote Control units together constitute
a unique, high-quality system for the remote control of
audio level. The DCA-2 is a compact (1-3/4” high) rack
mountable package that can control two discrete audio
channels (90 dB of isolation is provided for two unre-
lated programs) or the two channels can be linked to con-
trol a single stereo program. Multiple DCA-2s can be
linked, and up to 64 discrete channels can thus be con-
trolled in a single chain with 1/4 dB tracking tolerance
between channels. Designed for professional applica-
tions, the DCA-2 is equipped with XLR-type input and
output connections. The DCA-2T outputs are transformer
balanced. Either system is capable of driving 600 ohm or
higher impedance loads; maximum output is +18 dBm
terminated, +20 dBu unterminated.
Precise volume control can be provided at as many loca-
tions as required. The remote units are easily wired, in
“daisy-chain” configuration, using simple modular tele-
phone style cables. Up to four RC-16 remotes can be con-
nected to a given control input (and that remote, or string
of remotes, can be “daisy- chained” to control up to 64
audio channels). The system provides 29 steps of precise
1.5 dB attenuation from 0 to -43.5 dB, with a 30th step for
90 dB “full kill” attenuation. Virtual display of the set
attenuation is simultaneously given at all locations via a
circular LED array around the knob on each RC-16
Remote Control. The RC-16 can be mounted in a stan-
dard two-gang electrical wall box, or a pre-punched 2-
gang plate is available from Oxmoor. The maximum cable
length from the DCA-2 to the farthest remote is approxi-
mately 2,000 feet (see SPECIFICATIONS, page 13).
The RC-16 is actually a highly sophisticated shaft encoder
which translates knob movements into a string of digital
pulses; the pulses then alter the level of the digital
attenuator(s) within the DCA-2 chassis. Unlike up/down
buttons, the RCA-16 is sensitive to rate-of-change, and
thus the faster the knob is turned, the faster the setting is
changed. As any interconnected RC-16 knob is turned,
the LEDs on all remotes in the chain follow until the
upper or lower limit is reached. At that point, the knob
will continue to turn, but the level and Virtual Pointers
simply stop changing until any one of the knobs is turned
in the opposite direction. Since there are no mechanical
stops, a knob cannot be “twisted off” if it is turned
beyond what would be the “stop” positions on a con-
ventional level control.
The Oxmoor system includes a number of unique fea-
tures. A “Preset” control on the DCA-2 rear panel sets
the degree of attenuation exhibited when the system is
first powered up, avoiding an unpredictable or unknown
turn-on state. One or both channels can be switch-reset
back to this “Preset” level at any time. Another rear panel
control, labeled “Priority,” sets a level to which the
system can be temporarily forced by an external switch
closure. Each RC-16 remote has terminals for preset and
priority functions. The switch itself is not included.
Additionally, Channel A & B maximum gains can be
adjusted ±15 dB from the nominal unity gain of the
system via recessed, front-panel controls. For applications
where access to one or more remote controls must be
restricted, a key switch can be installed in place of a
jumper on the back of the RC-16; the key switch must
then close to activate the RC-16.
Installation of the DCA-2 Digital Control Attenuator and
RC-16 Remote Controls is straightforward. However,
there are a number of optional configurations. We there-
fore recommend that you read this entire manual once,
quickly. Note those items which apply to the set-up you
require, and then read the pertinent sections carefully
before installing your system. Basic hookup is shown in
the CONNECTIONS section (see page 5). More complex
hookups are illustrated and discussed in the CONFIGU-
RATION EXAMPLES section (see pages 6 through 9).
• UL and CE listed
• Front panel, screwdriver-adjustable gain trims
• Electronically balanced, XLR-type inputs
• Electronically balanced, XLR-type outputs (DCA-2T only)
• +18 dBu input signal levels
• +20 dBu output signal levels
• Built-in RF suppression
• Compact, 1U rack space chassis