LOW FREQUENCY FOLDED EXPONENTIAL HORN LOUDSPEAKER APPARATUS WITH BIFURCATED SOUND PATH

摘要

ABSTRACT OF THE DISCLOSUREA low frequency loudspeaker apparatus includes afolded exponential horn which is divided to provide abifurcated curved sound path from at least one electroacoustictransducer that is positioned at the throat of the horn to avolume into which sound waves are radiated that is located atthe bifurcated mouth of the horn. The mean length of thefolded exponential horn is such that, at an exponential rateof expansion between the throat and the bifurcated mouth,the area of the mouth is adequate for reproduction of lowfrequencies in the audible range. An illustrative embodimentof the low frequency loudspeaker apparatus has an effectivelow end cut-off frequency of 38 Hz. and affords 99 dB SPLoutput at three meters with one watt input which correpondsto about 20% efficiency measured in free space. Presenceof a single boundary surface, such as a stage floor adjacentthe mouth of the folded exponential horn, improves amplituderesponse by 3 to 6 dB.