The TL 128 transformer can be used in sound systems with constant voltage loudspeaker lines to adjust the power of one or more loudspeakers equipped with line transformer and having a max. total power not higher than 120 W. Thanks to its sockets with decreasing transformation ratios, the voltage applied to loudspeakers can be selected among 7 different values (100, 70, 50, 35, 25, 18, 12 V) to get different levels. The TL 128 transformer can be matched to a 8 position commutator (7 + off) in order to get a volume control (with 3 dB steps).