STA-2A Dual High-Gain Line-Level Preamplifier
The audio line amplifier shall be an RDL STA-2A. The unit shall provide two independent audio preamplifiers, A and B. Each preamplifier shall be equipped with one line-level balanced input, one line-level balanced output and a multi-turn gain trimmer. Each input and output shall be fully compatible with unbalanced wiring configurations. The unit shall be rated for stereo or dual mono operation.

Inputs shall be active balanced bridging with a nominal input impedance of 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 for each preamplifier 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 be capable of negative gain.  The nominal range of each gain trimmer shall be -14 dB to +24 dB. The unit shall operate without clipping an input signal up to +24 dBu.

The unit shall provide audio frequency response of 10 Hz to 100 kHz (± 0.05 dB) with total harmonic distortion plus noise  less than 0.004% (20 Hz to 20 kHz), intermodulation distortion less than 0.005% and a noise floor exceeding 90 dB below the normal rated output level. Each line input shall provide common mode rejection greater than 60 dB from 50 Hz to 120 Hz. The unit shall provide headroom of no less than 20 dB above +4 dBu. The output stage shall be capable of an unclipped output level of up to +25 dBu.

Crosstalk between the two preamplifiers shall be at least -80 dB at unity gain.

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 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. Controls shall be oriented toward the 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 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 STA-2A