Sigma ADA-26S Instruction Manual

ADA-26S

STEREO AUDIO

DISTRIBUTION AMPLIFIER

INSTRUCTION MANUAL

SIGMA ELECTRONICS, INC.

P.O. Box 448

1027 COMMERCIAL AVENUE

EAST PETERSBURG, PA 17520-0448

[phone]

ADA-26S STEREO AUDIO DISTRIBUTION AMPLIFIER

GENERAL:

The ADA-26S Stereo Audio Distribution Am plifier is designed to operate in two differ ent modes. The first
mode provides three (3) dual-channel outputs from a stereo audio signal source. The other mode provides six
(6) single-channel outputs from a m onaural audio signal sourc e. The desir ed mode c an be selected fr om the
front panel.
In either mode, the module is compatible with either balanced or unbalanced audio signals on the input
and outputs. Outputs can be mixed between balanced and unbalanced configuration dependent on the
requirement of the destination equipment.

POWER:

The ADA-26S operates from an AC power source of 120VAC or 230 VAC at line frequencies of 60 Hz or
50 Hz. The unit is supplied with an IEC 320 power inlet on the rear panel and a cordset with either a NEMA5­15P or CEE7/7 plug.
Internally the unit has bus voltages of +15Vdc and -15Vdc supplied by regulators U01 and U02 respectively.
An LED on the circuit board illuminates the front panel when both supplies are operating properly.
Circuit protection is provided by the externally accessible fuse on the rear panel. Refer to the specification
section for proper fuse value.

FRAMES:

The ADA-26S module is mounted within a stand-alone box. The all-metal enclosure provides desirable
shielding to external EMI/RFI noise sources.
Rack-mounting requir es the RMK-26 rack -mount k it. One RMK-26 rack -mount k it holds up to three of the 26
series units. Sigm a provides various dis tribution am plifier s, signal gener ators and trans coding produc ts in the
26 series.

CONNECTIONS:

Wiring to the module is performed via detachable screw terminal connectors (Figure 1).
INPUT: There are dual-channel inputs on the rear panel of the unit; the firs t and last connectors (Figure

2). The Right channel is on the left and the Left channel is on the right as seen from the rear of the unit. When
the unit is configur ed to pr ovide s ix ( 6) outputs f r om a single input, the “Left Input” is disabled (the input on the
right).
Both inputs are a high im pedanc e conf iguration. T his allows the audio signals to be bridged to other units .
To ensure proper impedance matching it may be necessary to terminate the outputs with a 600Ω load. It is
recommended that, if termination is necessary, use a 600Ω, 1/2 watt resistor across the (+) and (-) outputs.
When multiple units have inputs bridged to the same sourc e, only apply the 600Ω resistor to the last unit in the
line.
OUTPUT: T here are three (3) outputs on the rear panel of the unit for each channel . Each output is
designed to drive a 600Ω load. Since each output on a channel is identical, the numbering is only provided for
the operator’s convenience. W hen the unit is configured to provide six (6) outputs from a single input, both
the right and left outputs will provide the same signal.

Figure 1
AUDIO CONNECTOR

ADA-26S

Doc. No. – 14480

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