Radio Systems ADA-2x8SS Manual - Overview

R a d i o   S y s t e m s ,   I n c .

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Overview

The Radio Systems DA-4x4a is designed to function as a super low noise, low distortion

audio distribution amplifier which may be user wired to function in various flexible input

and output configurations.

Excellent isolation is provided between outputs.  Each balanced channel, regardless of

level set and load, is unaffected by the other channels.  The Radio Systems DA-4x4a

Distribution Amplifier allows audio sources to be routed to multiple locations with

various level requirements and impedances while maintaining the integrity of signal

quality throughout.

The distribution amplifier is configurable to a dual channel, 2x4 output version, or quad

channel, 4x4 output version.

Mounting

The 4x4a occupies only 1 rack unit (1-3/4 inch) of height in a 19 inch EIA rack.  To allow

for adequate ventilation, avoid mounting the unit directly above large heat producing

equipment such as power amps or power supplies.

When stacking units, it is recommended that one rack space (1-3/4 inch) remain open

between every three units.

Operation

Apply an input level of approximately 0dB to the input terminals.  The gain of any stage

may be increased by 20dB in 10dB steps by changing the internal gain straps.

To locate and reset these jumpers, refer to the parts layout for the location of JU1 and

JU2.  The lid of the unit must be removed to access these jumpers.  Place a shorting strap

across the center and rear pin (pin towards the rear barrier strip) to increase input gain by

10dB.  Place a shorting strap across the center and forward pin to increase input gain by

20dB.

Output level is factory set for unity gain.  Each output can be individually set via its front

panel recessed level pot over a range from –60 to  +18dBm.  Nominal operating levels

are 0dBm input and +10dBm output.  Higher operating levels can cut dynamic range by

operating too close to the clipping point.  Adjust each output to the desired level,

keeping clipping in mind.

Connections

The units are primarily designed for balanced inputs and outputs.  The input ground is

connected to the chassis and power supply at a single point.  If unbalanced lines are

used, tie the unused input terminal to ground.  However, do not tie any unused output

terminals to ground.  Wire an unbalanced output between one output terminal and the

input ground terminal.  For further details, see the section on using active balanced

circuitry in this manual.

Although the outputs are short circuit protected, operating into less than a 600 ohm load

is not recommended.  The input is bridging (high impedance) and will not load down any