RDL STVCA3 Voltage Controlled Amplifier

Herman # RDLSTVCA3




The ST‑VCA3 is used in applications requiring smooth audio level control from a remote control panel, potentiometer or dc voltage (0 to 10 V). Installation in series with the audio input of a power amplifier allows remote control of that amplifier's level. For installations where it is preferred to keep the audio localized in the rack, audio controls are extended outside the rack from the ST‑VCA3. Many installations benefit from avoiding long‑term potentiometer wear from audio running through the potentiometer. An ST‑VCA3 with external dc control provides virtual immunity from scratchy audio. Audio/video system control units often provide 0 to 10 Vdc control outputs that can directly control audio levels using an ST‑VCA3. The ST‑VCA3 is primarily intended for line‑level attenuation; a high quality utility microphone preamplifier is included in the module. If remote control of a microphone preamplifier is desired, such as a wall mounted level control for a microphone jack, the ST‑VCA3 may serve as a remote controlled microphone preamplifier.

  • Audio Level Control from a DC Voltage
  • Audio Level Remote Control
  • Two Wire with Shield or Three Wire Control
  • VCA with Microphone or Line Level Input
  • VCA with Line‑Level Output
  • VCA with LED Metering of Operating Level


Inputs (2):

Mic: 200 Ω balanced; 5 kΩ unbalanced


30 kΩ bal. bridging or unbalanced

Input Levels (for +4 dBu output):

Mic: –44 dBu to –60 dBu (150 Ω source)
Line: ‑18 dBu (‑20 dBV) to +4 dBu

Output Signal (normal rated):

+4 dBu, 150 Ω balanced


18 dB


Mic: < 0.05%; Line: <0.025% (unity gain);
0.025% typical at 15 dB attenuation

Frequency Response:

Mic: 30 Hz to 20 kHz (±1 dB)
Line: 10 Hz to 20 kHz (±0.1 dB)


Mic: < ‑71 dB below +4 dBu output (150 Ω source; 50 dB gain)
Line: <‑78 dB below +4 dBu output (maximum gain)


Mic: > 60 dB; Line: > 60 dB, (50 Hz to 120 Hz)

Control Input:

0 to 10 Vdc or 0 to 10 kΩ Linear

Attenuation Range:

0 to 90 dB (>90 dB at 0 Vdc control)

Power Requirement:

GROUND‑REFERENCED, 24 to 33 Vdc @ 50 mA


Height: 0.7 in. (1.7 cm),
Width: 3 in. (7.6 cm),
Depth: 1.6 in. (3.9 cm)

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