ST-VCA3 Voltage Controlled Amplifier The voltage controlled line amplifier shall be an RDL ST-VCA3. The unit shall provide one line-level input, one mic-level input and one line-level output. Both inputs must be active so that either input may be used. The unit shall include a provision to set the maximum gain applied to the input signal. The output level shall be adjusted using an external dc voltage source between 0 and 10 Vdc. The unit shall produce an audio taper attenuation for linear changes in the control voltage. The unit shall provide a 10 Vdc precision reference permitting an external potentiometer to provide the control voltage to the unit. The unit shall be directly compatible with RDL VCA switched and variable wall controls and with external linear taper potentiometers. The unit shall provide attenuation using solid-state technology that retains the audio in the analog domain. DSP or other products that convert the audio between analog and digital formats shall not be considered equivalent to the ST-VCA3. The microphone input shall be electronic balanced bridging with a nominal input impedance of 200 O and shall be fully compatible with either an unbalanced or balanced audio source. The unit performance shall be optimized to the line-level input which shall be electronic balanced bridging with a nominal input impedance greater than 30 kOhms and which shall be fully compatible with either an unbalanced or balanced audio source. A multi-turn continuously adjustable trimming control shall be provided to set the microphone gain to produce the rated output level for a 150 O microphone input level between -60 dBu and -44 dBu or for a line-level input between -18 dBu and +4 dBu. The unit shall provide a dual-LED VU meter to indicate proper adjustment of the input gain. When the audio output from the unit is not attenuated (control voltage at 10 Vdc), the dual-LED meter shall be calibrated to a +4 dBu output level. A green LED shall display a correlated linear minimum to maximum intensity for signal levels of -11 dBu to +4 dBu. A red LED shall indicate signals exceeding +4 dBu. The unit shall provide an LED attenuation level indicator that varies in intensity as a visual indication of the relative applied control voltage or position of the external linear-taper control potentiometer. The unit shall provide a mic input audio frequency response of 30 Hz to 20 kHz (± 1 dB) with total harmonic distortion plus noise of <0.05% (20 Hz to 20 kHz) and a noise floor exceeding 70 dB below the normal rated output level with the input adjusted to 50 dB gain. The unit shall provide a line input audio frequency response of 10 Hz to 20 kHz (± 0.1 dB) with total harmonic distortion plus noise <0.025% (20 Hz to 20 kHz) and a noise floor exceeding 78 dB below the normal rated output level with the input adjusted to unity gain. Each input shall provide common mode rejection greater than 60 dB from 50 Hz to 120 Hz. The applied dc control voltage shall attenuate the unit output level between 0 dB and -90 dB. The off attenuation shall exceed 90 dB with 0 Vdc control voltage. The unit shall provide a line-level balanced audio output at a nominal rated output level of +4 dBu with an output impedance of 150 O. The output circuit shall be configured to produce an unbalanced output of proper phase between the positive output leg and ground. The unit shall be constructed in an electrically non-conductive, thermally conductive enclosure. Internal circuitry shall be protected from moisture and vibration using a thermally conductive compound that permanently secures the circuitry within the enclosure. The face of the unit shall provide graphical labels identifying wiring connections and operating controls. Indicators and controls shall be oriented toward the front edge of the unit. Connection to external wiring shall be provided using a fixed terminal block on the edge of the unit. The terminal block shall accept wiring gauges from 14 to 22 and shall include a positive electrically conductive mechanism to prevent wire abrasion by the terminal screws. The unit shall measure 3” (7.6 cm) x 1.6” (4 cm) x 0.7” (1.7 cm) and be compatible with all RDL STICK-ON mounting accessories. The unit shall be supplied with a two part re-closable polypropylene fastener system equipped with a rubber adhesive that bonds to low surface energy materials. Power requirements shall be 24 Vdc ground-referenced with a maximum current not exceeding 50 mA. The unit shall utilize an external power supply. The unit shall be engineered, assembled and tested in the U.S.A. and be specified for continuous duty in professional installed systems. The unit shall be specified for operation in an ambient temperature between 0 and 55 degrees C. The unit shall comply with relevant EMC requirements and shall bear the CE marking. The unit shall be an RDL ST-VCA3.