LOUD SPEAKER Russian patent published in 2010 - IPC H04R1/28 

FIELD: physics; acoustics.

SUBSTANCE: invention relates to electroacoustics, particularly to compact high-quality loud speakers for sound-reproducing equipment. The loud speaker has a housing, an electrodynamic head rigidly attached to the housing, and a passive radiator. Between the electrodynamic head and the passive radiator there is an acoustic channel whose cross sectional area is (0.1-0.5)S_dif, area of the passive radiator is (1-20)S_dif, length of the channel is selected from the condition (0-0.4)D and distance between the electrodynamic head and the passive radiator is equal to (0.01-0.5)D, where S_dif is area of the diffuser of the electrodynamic head; D is diametre of the passive radiator. The acoustic channel is made in form of a pipe placed coaxially with the electrodynamic head. For accurate tuning, the acoustic channel can be made telescopic.

EFFECT: increased efficiency of radiation of the loud speaker in the low-frequency range and reduced distortion of high-frequency sound signals.

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