DCA-2T Digital Control Attenuator

The Oxmoor line of attenuators and remote controls constitute a unique, high quality system for the remote control of audio levels. Over the years, many audio professionals around the world have come to rely upon our remote volume control products, especially in situations where other remote volume controls have failed to meet quality and long-term wear and tear standards.

At the heart of our remote volume control products is our DCA-2T digital control attenuator. The DCA-2T is a sleek, rack-mountable box that provides control of two discrete audio channels (90 dB of isolation provided for two unrelated programs), or control of a single stereo program.

Multiple DCA-2Ts can be linked together to provide up to 64 discrete channels. The DCA-2T features user-assigned preset levels to control the amount of attenuation at power up, eliminating unpredictable or unknown turn-on state, as well as a "priority" function to set a temporary system level upon a switch closure, ideal for fire alarm or paging applications.

Precise volume control can be provided at as many locations as required. Our RC-16 remote controls are easily wired and linked together using simple RJ-11 modular telephone cables. Up to four RC-16 remotes can be connected to a given control input. There are 29 steps of precise 1.5 dB attenuation from 0 to -43 dB, with a 30th step for 90 dB "full kill" attenuation.

The RC-16 is actually a highly sophisticated shaft encoder which translates knob movement into a string of digital pulses. Unlike standard "Up and Down" volume controls, the RC-16 is sensitive to rate of change between steps – so 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 DCA-2T features electronically balanced inputs and balanced transformer-isolated outputs, with XLR connectors. It is used with the Oxmoor RC-16 remote volume control and requires one rack space.

DCA-2T Part Number: 2500002

Downloadable files for this product

cut sheet (138 kB; PDF)
manual (507 kB; PDF)
high-resolution line drawings (29.6 kB; zipped TIFFs)
product photos (62.1 kB; zipped JPEGs)

Product specifications

Frequency Response	20 Hz to 20 kHz -3 dB Points, Ref. 1 kHz	+0, -0.3 dB 4 Hz to 60 kHz (+4 dBm Output)
Hum and Noise	Unweighted	-80 dB (ref. 0 dBm output @ unity gain)
Distortion	Ref. +4 dBm Output @ Unity Gain
	THD + Noise	0.002% (20 Hz to 20 kHz BW)
	SMPTE IMD	0.002% (60 Hz + 7 kHz, Mixed 4:1)
	Transient Intermodulation	0.004% (3.15 kHz SQ + 15 kHz Probe, 30 kHz BW)
Crosstalk	Channel to Channel (20 Hz to 20 kHz, Input Terminated w/600 Ohms, Adjacent Channel Driven to 0 dBm)	-90 dB
Audio Input	Type	Electronically Balanced (RF Suppressed)
	Connector	Female XLR
	Pin Out	Pin 1 Shield (Chassis), Pin 2 +, Pin 3 –
	Input Impedance	80 k Ohms
	Nominal Input Level	+0 dBu
	Maximum Input Level	+20 dBu
	Trim Pot Gain Range	±15 dB (Ref. 0 dBu Output)
Audio Output	Type	Balanced, Transformer-isolated
	Connector	Male XLR
	Pin Out	Pin 1 (Chassis), Pin 2 +, Pin 3 Shield
	Source Impedance	75 Ohms
	Recommended Load Impedance	600 Ohms or Greater
	Nominal Output Level	0 dBu
	Maximum Output Level	Ref. 1 kHz @ Rated THD
	Terminated w/600 Ohms	+18 dBm (All Outputs Driven Simultaneously)
	Unterminated	+20 dBu
Digital Attenuator	Control Range	0 to -43.5 dB in 29 Steps Plus a 90 dB Full Attenuation "Kill" Step
	Tracking Accuracy (Ch. to Ch.)	Within ±0.1 dB Throughout Attenuator Range
	Preset and Priority Range	15 Steps (of 3 dB each) Plus "Kill"
Control Loop	Maximum Controls Per Channel	4
	Maximum Channels Per Control Loop	64
	Maximum Cable Length	600m (2000 ft)¹
	Contact Requirements	Single Pole Switch or Open Collector Transistor (128 mA capacity), Dry Closure to Logic Ground
	Wiring Scheme	Daisy-Chained Connection Via Looping Jacks
	Cable and Connectors	6-Wire Modular Telephone type RJ-11/12
Safety Listing	City Of Los Angeles
Mains Power	Power Requirements	100 to 125 VAC or 200 to 230 VAC 50/60 Hz; 8 Watts Maximum
Mechanical	Overall Dimensions	44H x 482W x 183D mm (1.72 H x 19 W x 7.18 D in)
	Finish	Textured Black Paint
	Shipping Weight	3.8 kg (8.5 lb)
	Net Weight	3.1 kg (6.9 lb)

¹ Total length based on typical modular telephone cable resistance of 12 ohms per 100m (330 ft).

Specifications subject to change without notice. The term DCA is a trademark of the Oxmoor Corporation.

Architect and engineer's specifications

Digital control Attenuator (DCA). Two-channel audio attenuator utilizing precision D/A converters. Range of attenuation: 43.5 dB in 29 steps, plus a -90 dB full attenuation ("kill") position. Front panel (recessed) ±15 dB trim controls. Each channel may be controlled independently or ganged for stereo. Channel tracking: ±0.25 dB over entire attenuation range when ganged for stereo operation. Attenuation position self-contained and not effected by disconnection of remote controls. Frequency response: +0, -0.3 dB, 20 Hz - 20 kHz. Hum and noise (ref. +0 dBm output at unity gain): -80 dBu, unweighted. Distortion (ref. +4 dBm, 20 Hz to 20 kKz): THD or IMD, 0.1% or less, 20 Hz - 20 kHz. Audio inputs: electronically balanced, 3-pin XLR-type. Input impedance: 80 K ohms. Audio outputs: balanced transformer-isolated, 3-pin XLR-type. Source impedance: 75 ohms. Maximum input/output level: +20 dBu. Remote control ports: "volume up," "volume down," "preset," and "priority." User-adjustable wake-up level ("preset") on power up. User-adjustable momentary level change ("priority") through external contact closure. Mounting: rack-mountable, one EIA rack space (44.45 mm; 1.75 in.).

Acceptable: Oxmoor DCA-2T