The low bass extension should contain two 18 inch long excursion loudspeakers in a bass reflex tuned cabinet. The used loudspeakers should be impregnated weatherproof. The continuous load capacity of the system should be 2,500 watts. The loudspeaker should have a nominal impedance of 4 Ohm. The usable system bandwidth should be extended down to 30 Hertz (-6 dB) by using the low bass extension. The system should have an omnidirectional radiation characteristic. The low bass loudspeaker should have an M20 thread on its upper side for a 36mm high stand flange to accommodate a full-range loudspeaker. The maximum peak sound pressure level should be 144 dB, measured with pink noise at a distance of 1m, under half-space conditions and with a crest factor of 6. The loudspeaker cabinet should be made of birch multiplex and sealed with a weather and moisture resistant polyurea coating (PU). The front of the loudspeaker should be provided with a ball-proof protective grille, which is backed with acoustically neutral foam. Its physical dimensions should be 1108 mm in width, 497 mm in height and 750 mm in depth. The weight of the loudspeaker shall be 77 kg. The loudspeaker should be connected via two 4-pole SpeakON sockets on the rear panel. The manufacturer's warranty shall be 5 years. 
GAEB
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U4-SUB is a high performance sub-extension for touring and installation applications. It has a transmission range of 30Hz - 150Hz (-6dB), an AES power of 2,500 W and can reach a peak level of 144 dB (6dB Crest). The system is operated, controlled and monitored by an external CODA AUDIO LINUS system amplifier.