Loudspeakers

Reflexing loading uses the Helmholtz resonance between the mass of air in the port and the compliance (springiness) of the air contained within the enclosure to reinforce bass output when both port and driver are in phase. Reflex loading increases sensitivity and reduces distortion but there are also downsides, particularly if airflow through the port becomes turbulent, adding various 'chuffing' noises at high output. Furthermore, while 'organ pipe' resonances can occur within the port tube itself, Sonus faber's patented 'Stealth Ultraflex' system is termed 'para-aperiodic' (almost non-resonant), because the inner surface of the port duct – an extruded aluminium spine, offset from the rear of the speaker – is lined with sound absorbent material. It is claimed to provide a reduction in cabinet size, greater bass extension, reduced distortion and the elimination of port noise. KH