The DEL 165/6-A/B PP 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 ceiling speaker suitable for diverse acoustic irradiations. The exceptional spring mounting with cropped leg springs guarantees an outstanding rapid ceiling installation.