The ST-VCA3 is a high performance voltage controlled amplifier with two inputs and one output. The line input is designed to accept an input signal with operating levels between -20 dBV and +4 dBu. The microphone input accepts low or high impedance microphones with output levels from –60 to –44 dBu. Only one of the inputs may be used at a time.

A multi-turn trimmer is provided for setting the correct input gain according to the dual-LED VU meter located directly in front of the gain control. The intended output level is +4 dBu for 10 Vdc at the CTRL input terminal. The green metering LED begins illuminating at 15 dB below +4 dBu. The green LED progresses to full intensity at +4 dBu. The adjacent red LED illuminates at +4 dBu. Terminals are provided for connection of an external ramp generator (0 to 10 Vdc) or a linear taper 10 kΩ potentiometer remote control. The RDL RLC10K is most commonly used.

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 a rack or common equipment location, audio level control may be extended outside the rack using an ST-VCA3.

Many installations benefit from avoiding long-term wear from audio running through a 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 adjust audio levels using an ST-VCA3. The ST-VCA3 is primarily intended for line-level attenuation although 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. The ST-VCA3 operates from a 24 Vdc ground-referenced power supply.

Features:

• 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