| 摘要 |
PURPOSE:To prevent the rapid reduction in the sound pressure level at a low frequency by mounting speaker units of a same characteristic to both buffle plates opposite to each other, covering a rear side of the one with a sound absorbing member and connecting the units electrically so as to be in operation in opposite phase. CONSTITUTION:Speakers 1, 2 of a same characteristic are mounted to a buffle plate 4 of a cabinet 3, a rear part of the speaker 2 is covered by a sound absorption material 6 and the speakers are interconnected to an input terminal 7 by internal wiring members 8a, 8b so that they are operated in opposite phase. Since the sound radiating from the speaker units 1, 2 at middle and high frequencies is of the same amplitude but in opposite phase, a dipole directivity is provided and since the rear side of the speaker 2 is covered by the sound absorption material, the amplitude of the diaphragm of the speaker unit 2 is more limited than that of the speaker unit 1, the cancellation of the sound pressure is relaxed and a rapid decrease in the sound pressure level at a low frequency is prevented. |
