Oxmoor DCA-2 Digital Control Attenuator 2-Channel 20 Hz to 20 kHz

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 unrelated programs) or the two channels can be linked to control a single stereo program. Multiple DCA-2s can be linked, and up to 64 discrete channels can thus be controlled in a single chain with 1/4 dB tracking tolerance between channels. Designed for professional applications, 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 locations as required. The remote units are easily wired, in “daisy-chain” configuration, using simple modular telephone style cables. Up to four RC-16 remotes can be connected 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 standard 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 approximately 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 conventional level control.

The Oxmoor DCA-2 Digital Control Attenuator includes a number of unique features. 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 Control is straightforward. However, there are a number of optional configurations. We therefore 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 CONFIGURATION EXAMPLES section (see pages 6 through 9).