ST-MX3 Line Level Mixer The audio mixer shall be an RDL ST-MX3. The unit shall provide three line-level balanced inputs and one line-level balanced output. Each input shall be equipped with a single-turn trimmer to set the level that feeds the output. Signal mixing shall incorporate active mixing techniques. Inputs shall be electronic balanced bridging with an input impedance no less than 30 kOhms and shall be fully compatible with either an unbalanced or balanced audio source. A single turn continuously adjustable trimming control shall be provided to set the gain to produce the rated output level for a line-level input level between -20 dBu and +18 dBu. The unit shall provide audio frequency response of 10 Hz to 20 kHz (± 0.5 dB) with total harmonic distortion plus noise <0.03% (10 Hz to 20 kHz) and a noise floor exceeding 80 dB below the normal rated output level with all inputs adjusted to unity gain or to + 10 dB gain. The noise floor shall exceed 80 dB below the normal rated output with all inputs adjusted to +10 dB gain. Each line input shall provide common mode rejection greater than 50 dB from 50 Hz to 120 Hz. The unit shall provide headroom of no less than 16 dB above +4 dBu at each input, and no less than 22 dB above +4 dBu at the output. The front-panel mixing trimmers shall adjust the gain applied to the input signal within the range of -14 dB and +24 dB. The unit shall provide a line-level balanced audio output at a nominal rated output level of +4 dBu with an output impedance no higher than 400 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 shall be oriented toward the front edge of the unit. Controls and switches shall be oriented toward the face 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. The unit shall be equipped to operate from either 24 Vdc ground-referenced power or from bipolar ± 12 Vdc or ± 15 Vdc power with a maximum current not exceeding 55 mA. The unit shall utilize an external power supply and shall be equipped to operate from 24 Vdc ground-referenced or bipolar ± 12 Vdc or ± 15 Vdc power. 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-MX3.