The surface-mounted ceiling speaker is equipped with two independent transformer / loudspeaker- combinations and allows loudspeaker’s supply by two different wires. By the traditional alternating division of the loudspeakers in the A- and B- line, the breakdown of one line causes an unsupplied area between the next active loudspeaker of the redundancy. Using the loudspeakers of the A/B series the A- as well as the B- line is existing in every mounting position. Accordingly the level loss in the considering area is lighter. If one line fails there will be a higher comprehensibility of speech and security compared to an alternating configuration. The classic appearance and the brilliant acoustic features make this surface-mounted ceiling speaker suitable for a wide variety of applications. The mounting brackets allow the installation on ceilings and walls, even where a regular installation would not be possible.