ST-DA3 Line-Level Audio Distribution Amplifier
The audio distribution amplifier shall be an RDL ST-DA3. The unit shall provide one balanced line-level input and three balanced line-level outputs, a multi-turn gain trimmer and an LED power indicator. 

The line-level input shall be active balanced with an input impedance no less than 20 kOhms and shall be fully compatible with either an unbalanced or balanced audio source. A multi-turn continuously adjustable trimming control shall be provided to adjust the input gain to unity, ± 17 dB to set the output level to +4 dBu for input levels from -15 dBV to +21 dBu.  The input stage shall operate normally for audio inputs up to +24 dBu.

The unit shall provide unity-gain audio frequency response of 10 Hz to 100 kHz (± 0.05 dB) with total harmonic distortion of less than 0.002%, intermodulation distortion of less than 0.003% and a noise floor exceeding 98 dB below the normal rated output level of +4 dBu. 

The input shall provide common mode rejection greater than 60 dB from 50 Hz to 120 Hz. The unit shall provide output headroom of no less than 20 dB above the rated output level.

The unit shall provide three line-level balanced audio outputs 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 three outputs shall be driven from separate, isolated output amplifiers so that either a short circuit on one output or a signal fed into one output cannot affect the remaining outputs. The unit shall not provide separate level controls for each of the outputs. 

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 the gain control trimmer 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.

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 70 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-DA3