| 摘要 |
PURPOSE:To prevent the reduction in a sudden sound pressure level at a low frequency by driving 1st and 2nd speaker units in phase at a frequency below a phase inversion frequency of an all path circuit so as to prevent cancellation due to an inverted phase. CONSTITUTION:A 1st speaker unit 1 is fitted to one buffle face of a cabinet 3 and a 2nd speaker unit having the same characteristic as that of the speaker 1 is fitted to a buffle face opposite to the buffle face on which the speaker 1 is mounted. An all pass circuit 4 is connected to the speaker 1 and the phase is inverted around the frequency f1 as a border. Then both the speakers 1, 2 are driven in opposite phase at a frequency band more than the frequency f1 and driven in in-phase for a frequency band below the frequency f1. Since the speakers having dual directivities are provided, a decrease in a rapid sound pressure level at a low frequency is avoided and an excellent surround effect is obtained. |
