Power Amplifire: LBB1938

Power Amplifier

The LBB 1938/20 is a powerful 480 W power amplifier in a 3U high 19” case for rack mounting or tabletop use. LEDs on the front panel show the status of the Power Amplifier, audio output level, and supervised functions. This high-performance unit fulfils a wide range of public address requirements at a surprisingly low cost.

The Power Amplifier is protected against overload and short circuits. A temperature-controlled fan ensures high reliability at high output levels and low acoustic noise at lower output levels. An overheat protection circuit switches off the power stage and activates an LED on the front panel, if the internal temperature reaches a critical limit due to poor ventilation or overload. The unit operates both on mains power and on a 24 V battery power supply for emergency backup, with automatic switchover.

For emergency and evacuation use, the following functions are monitored: mains presence, battery present, pilot tone presence, amplifier operation. Front panel LEDs indicate the status of supervised functions. The LEDs of pilot‐tone supervision and battery status can be switched off for general public address use. Failsafe (normally energized) relays are provided for each supervised function. These relays are always active regardless of the switches on the rear panel.