ST-SX4 Unbalanced Audio Switcher

The unbalanced line-level audio switcher shall be an RDL ST-SX4. The unit shall provide four mono unbalanced inputs, one mono unbalanced output and a provision for remote input selection. The inputs and output shall be consumer line-level.

The unbalanced inputs shall have an input impedance no less than 100 kOhms. No gain shall be applied to the input signals.

The unit shall provide an audio frequency response of 15 Hz to 40 kHz (± 0.5 dB) with total harmonic distortion plus noise of <0.1% (20 Hz to 20 kHz) and a noise floor exceeding 70 dB below the normal rated output level with an input of -10 dBV. Attenuation of deselected inputs shall exceed 85 dB at 1 kHz, 80 dB at 10 kHz and 75 dB at 20 kHz. The unit shall provide headroom of no less than 23 dB above the normal rated output level.

The unit shall provide a line-level unbalanced audio output at a nominal rated output level of -10 dBV with a minimum output impedance of 50 O.  The gain between any selected input and the output shall be unity nominal.

The source shall be selected according to an externally connected resistance between a single control terminal and the unit’s ground terminal.  The required resistors shall be supplied with the unit. Direct connection of the control terminal to the ground terminal shall deselect all inputs. An open control terminal shall select input #4.

The unit shall be capable of source selection using a direct connection to an RDL RC4-ST remote control.  A slave output terminal shall be provided to connect an additional ST-SX4 unit providing source selection of a second set of audio sources, together providing stereo source selection. 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.

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 45 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-SX4.