Sigma ADA-26A Instruction Manual

ADA-26A

AUDIO

DISTRIBUTION AMPLIFIER

INSTRUCTION MANUAL

SIGMA ELECTRONICS, INC.

P.O. Box 448

1027 COMMERCIAL AVENUE

EAST PETERSBURG, PA 17520-0448

[phone]

ADA-26A AUDIO DISTRIBUTION AMPLIFIER

GENERAL:

The ADA-26A Audio Distribution Amplif ier is designed to provide s ix (6) outputs f rom a single audio signal
source. The unit is com patible with either balanced or unbalanced audio signals on the input and outputs.
Outputs can be mixed between balanced and unbalanced c onfiguration dependent on the requirement of the
destination equipment.

POWER:

The ADA-26A operates from an AC power source of 120VAC or 230 VAC at line frequencies from 50 Hz to
60 Hz. The unit is supplied with a line cord terminated with a three-prong grounded 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-26A module is mounted within a stand-alone box. The all-metal enclosure provides desirable
shielding to external EMI/RFI noise sources.
Rack mounting requires the RMK-26 rack -mount k it. One RMK-26 rack -mount k it holds up to three of the 26
series units. Sigma provides various distr ibution am plifier s, signal generators and transc oding produc ts in the
26 series.

CONNECTIONS:

Wiring to the module is performed via detachable screw terminal connectors (Figure 1).

INPUT: There is a single input on the rear panel of the unit (Figure 2). The INPUT is a high impedance
configuration. This allows the audio signals to bridge to other units. To ensure proper im pedance matching it
may be necessary to terminate the outputs with a 600Ω load. For termination, it is r eco mmended that a 600Ω,
1/2 watt resistor be placed between the (+) and (-) outputs. When m ultiple units have inputs bridged to the
same source, only apply the 600Ω resistor to the last unit in the line.

OUTPUT: Ther e are s ix ( 6) outputs on the r ear panel of the unit. Eac h output is des igned to drive a 600Ω
load.

I

-

N

C

P

+

U
T

120/240V~

50/60Hz

12W

ADA-26A

Figure 1

AUDIO CONNECTOR

OP
UU

TT

S

­C
+

1

­C
+

2 3 4

T125mA/T63mA

­C
+

FUSE

250V

­C
+

­C
+

5

SIGMA ELECTRONICS, INC.

­C
+

T

CAUTION

RISK OF ELECTRIC SHOCK

6

REAR PANEL CONNECTIONS

Figure 2

ADA-26A Doc. No. – 13923

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