A speaker includes a housing; a support assembly installed on the lower end of the housing to support the housing; at least one first speaker unit installed in the housing to reproduce a sound signal; and a second speaker unit installed in the support assembly to reproduce a sound signal which belongs to a low sound band. Openings are defined through both sides of the support assembly to transmit to the outside sound reproduced by the second speaker unit. A guide cone is provided to the lower end of the support assembly to guide sound toward the openings. The speaker unit can be installed in a baffle which is supported at the opened front end of the housing to be rotated about a vertical axis. Through rotating the baffle, the speaker unit can be actually rotated within a predetermined range to change a sound transmission direction.