RDL STA-2A Dual High Gain Line Amplifiers

The STA-2A is a dual-channel, line-level audio preamplifier. Each channel is identical. The audio inputs are bridged at 20 kΩ and accept either an unbalanced or a balanced audio signal. Gain is adjustable from unity to +24 dB using a 25-turn precision audio taper trimming potentiometer. The output line driver circuits are designed to drive long balanced audio lines into 600 Ω loads.

The STA-2A features wideband circuitry for excellent phase response, low noise, low distortion and exceptional audio clarity. RDL's SupplyFlex power input configuration is included in the STA-2A. The power supply input may be fed from a floating (not ground-referenced) 24 Vdc power source, from a bipolar power supply (+/- 12 Vdc or +/-15 Vdc) or from a ground-referenced 24 Vdc power supply.

Many audio products provide optimum performance when feeding into a bridging input, but may not provide the output needed to directly drive low-impedance lines terminated with 600 Ω transformers. The STA-2A is specifically designed for such installations, and is also ideal in installations requiring high gain in line-level audio transmission.


  • Up to 24 dB Gain in Audio Lines
  • Conversion between Unbalanced and Balanced
  • Conversion between High and Low Impedance
  • Low-Impedance, High-Current Line Drivers
  • Dual-Channel Line-Level Preamplifiers
  • High Gain, High Output, High Performance
  • RDL® SupplyFlex™ Power Input Configuration

Amps per STA-2A:

2 identical circuits (stereo or dual mono operation)

Inputs (2):

20 kΩ balanced or unbalanced

Input Signal (for +4 dBu out):

-20 dBu (-18 dBV) to +18 dBu

Maximum Input Level:

+24 dBu

Outputs (2):

150 Ω balanced or 75 Ω unbalanced

Output Signal:


+4 dBu nominal


6 dB below balanced line level

Maximum Output Level:

+25 dBu

Frequency Response:

10 Hz to 100 kHz (± 0.05 dB)


< 0.004% (unity gain)


< 0.005% (unity gain)

Noise below +4 dBu:

< -90 dB (unity gain)


< -80 dB (unity gain)


> 20 dB (above +4 dBu)


Unity +24 / -14 dB (adjustable)


> 60 dB (50 Hz to 120 Hz)

Ambient Operating Environment:

0° C to 55° C

Power Requirement: