ST-PA6 Audio Power Amplifier
The audio power amplifier shall be an RDL ST-PA6. The unit shall provide two electrically isolated summed balanced inputs, one unbalanced amplified output capable of driving speaker loads of 4 O or greater, a single-turn gain trimmer and a single-turn low-frequency boost trimmer.

Line inputs shall be electronic balanced bridging with an input impedance no less than 100 kOhms and shall be fully compatible with either an unbalanced or balanced audio source. Signals applied to the two inputs shall be equally summed by the unit. Stereo separation of a connected stereo source shall be fully preserved by means of electrical isolation between each input. A single-turn adjustable trimming control shall be provided to set the amplifier gain.  The amplifier shall be capable of producing 6 W (RMS) into an 8 O load from an input level of 400 mV (RMS).

The unit shall provide a frequency response of 35 Hz to 20 kHz (± 1.5 dB with BASS EQ set flat) with total harmonic distortion plus noise <0.35% and a noise floor exceeding 60 dB below the normal rated output level. 

The unit shall provide an unbalanced mono amplified output at an output power of 6 W into a load impedance of 8 O. The unit shall include automatic shut-down circuitry to protect the unit from potential damage due to output over-current or overheating. The unit shall otherwise operate normally following application of a momentary or sustained short to its output.

A single-turn adjustable trimming control shall be provided to boost bass frequencies.  This control shall boost low frequencies at a center frequency of 60 Hz and shall be capable of boosting 60 Hz by a minimum of 5 dB, 100 Hz by a minimum of 4 dB, and 120 Hz by a minimum of 3 dB.

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 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.

Power requirements shall be 24 Vdc ground-referenced with a maximum current not exceeding 400 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 -10 and 50 degrees C. The unit shall comply with relevant EMC requirements and shall bear the CE marking.

The unit shall be an RDL ST-PA6.