PURPOSE: To obtain the optimum frequency characteristics which are well balanced in terms of the hearing sense in both sealed-up and bass reflex systems, by switching a high band characteristics changeover switch in response to a bass reflex/sealed-up system switching device.

CONSTITUTION: A tweeter 2, a woofer 3 and a buss reflex/sealed-up system switching device 5 are attached to a baffle plate of a cabinet 1. The device 5 closes the opening of a buss reflex port to switch the buss reflex system to a sealed-up system and opens the opening the bass reflex port to switch the sealed- up system to the bass reflex system. A high band characteristics changeover switch 6 interlocks the function of the device 5, and the output level of the tweeter 2 of a branch circuit 4 is switched by the position of the switch 6 as shown in the figure. As shown in the figure, the output of the tweeter 2 of the circuit 4 is attenuated at a position (a) of the switch 6 and not attenuated at a position (b) respectively.