A loudspeaker system includes a loudspeaker drive unit (1) and a rear sound absorption system (20) having a multiplicity of tubes connected to the rear of the loudspeaker drive unit. In one example, the rear sound absorption system (20) comprises a collector tube (22) for sound waves emerging from a passage in the magnet assembly of the loudspeaker drive unit, an annular diffuser (24) for sound waves coming from the back of the diaphragm (4), and a disk-shaped diffuser (26) for second waves collected by the collector tube (22). The disk-shaped diffuser (26) is part of a basket-like assembly (28) mounted on the rear of the magnet assembly (6). The annular diffuser (24) is mounted against the wall (2) of the enclosure in which the loudspeaker drive unit (1) is mounted. The annular diffuser (24) includes a base portion (24A) with integral upstanding vanes (24B) arranged in a spiral configuration. A multiplicity of channels (24C) are defined between the vanes (24A), and the wall (2) of the enclosure closes off the open faces of the channels (24C) so that they form a multiplicity of tapering tubes.