The amplifiers are protected against overload and sho circuits. A temperature-controlled fan ensures high reliability at high output power and low acoustic noise at lower power output. Additionally, all booster amplifiers have an overheat protection circuit that switches off the power stage if the internal temperatur reaches a critical limit due to poor ventilation or overload. The LBB 1930/x0 and LBB 1935/x0 has a balanced inpu and a loop-through connector for easy connection of multiple power amplifiers to increase the available output power. An additional 100 V line input is provided to connect th booster amplifiers to a 100 V loudspeaker line, for additional output power e.g. on remote locations. Sensitivity or level control is located on the rear of the unit to avoid accidental setting change. A VU-meter with LED-bar shows the output level. The amplifiers have 70 V and 100 V outputs for constant voltage loudspeaker systems and a low impedance output for 8 Ohm loudspeaker loads. The power amplifiers operate both on mains power and on a 24 V battery power supply for emergency back-up, with automatic switchover.
