RU-LB4 Line-Level Bi-Directional Network Interface The Line-Level Bi-Directional Network Interface shall be an RDL RU-LB4. The unit shall provide a Dante compatible Ethernet interface, four balanced professional line-level audio inputs and four balanced professional line-level audio outputs. The unit shall convert four networked Dante digital audio channels to analog audio and four analog audio sources to networked Dante digital audio channels. The unit shall provide network connection through an RJ45 type shielded connector equipped with LEDs for Link and Speed. The Speed LED shall illuminate when the unit is connected to a Dante network with a transmission speed of 100 Mbps. The unit shall support a bit depth of 24 bits and sample rates of 44.1 kHz and 48 kHz. The unit shall convert between digital and analog formats at nominal standard professional levels of +4 dBu for a digital audio value of -18 dBFS. Four audio inputs shall be provided on detachable terminal blocks. Each input shall accept balanced professional +4 dBu signal levels. The input impedance shall exceed 20 kOhms. Each input shall provide audio frequency response of 20 Hz to 20 kHz (± 0.5 dB) with total harmonic distortion of less than 0.05% and a noise floor exceeding 80 dB below the normal rated operating level of -18 dBFS, and a minimum of 18 dB of headroom above the normal rated operating level. Crosstalk between any pair shall exceed -85 dB from 20 Hz to 20 kHz. Common mode rejection shall exceed 60 dB for balanced line inputs between 50 and 120 Hz. For each input, a corresponding recessed, single-turn gain trimmer shall be provided in the front panel to produce normal operating level for an input range of -16 dBu to +12 dBu. The input shall not clip during application of an input signal up to +22 dBu. The unit shall provide a dual-LED VU meter for each input to indicate proper adjustment of the input gain. The dual-LED meter shall be calibrated to normal operating level. A green LED shall display a correlated linear minimum to maximum intensity for signal levels from 15 dB below normal operating level to normal operating level. A red LED shall indicate signals exceeding normal operating level. Four audio outputs shall be provided on detachable terminal blocks. Each output shall produce a balanced professional +4 dBu signal level for a nominal network digital audio level of -18 dBFS. The output impedance shall be 150 O balanced or 75 O unbalanced. The output circuit shall be configured to produce an unbalanced output of proper phase between the positive output leg and ground. The unit shall, for each output, provide audio frequency response of 20 Hz to 20 kHz (± 0.5 dB) with total harmonic distortion of less than 0.05% and a noise floor exceeding 80 dB below the normal rated output level of +4 dBu, and a minimum of 18 dB of headroom above the normal rated output level of +4 dBu. Crosstalk between any pair shall exceed -85 dB from 20 Hz to 20 kHz. During the absence of all digital audio inputs, the outputs shall fully mute with a residual noise at least 95 dB below the normal rated output level of +4 dBu. The unit shall provide a green LED signal presence indicator that varies in intensity as a visual indication of the relative audio level at each of the four channel outputs. The indicator shall provide positive visual indication of signal presence for signals exceeding an amplitude 20 dB below a normal operating level of +4 dBu. The front face of the unit shall provide graphical labels protected beneath a polycarbonate protective surface. The front face shall include LED indicators to indicate the presence of unit power, audio signals and Dante system and synchronization lock. The unit shall measure 5.8" (15 cm) W; 1.7" (4.3 cm) H; 5.2" (13.2 cm) D and be compatible with RDL RACK-UP mounting accessories. The unit’s electrical chassis shall be fully constructed of metal, comprised of aluminum and steel members. The chassis shall include an integral provision for surface mounting. The unit shall be equipped to operate from a 24 Vdc ground-referenced power supply with a maximum current not exceeding 140 mA. The unit shall utilize an external power supply connected through one of two power inputs, one detachable terminal block or one dc jack. 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 40 degrees C. The unit shall comply with relevant EMC requirements and shall bear the CE marking. The unit shall be an RDL RU-LB4.