The LBB 1938/20 is a powerful 48w power amplifier with a 3U 19-inch high cabinet that can be mounted on a rack or used on a desktop. The LED indicator on the front panel shows the state of the amplifier: power supply, audio output levels, and a variety of monitored functions. This high performance device can meet all kinds of public broadcasting requirements, and the cost is very low. Basic function reliability amplifier with overload and short circuit protection. The temperature controlled fan can guarantee high reliability when high power output and low noise when low power output. When the internal temperature reaches the critical limit due to poor ventilation or overload, the overheat protection circuit will turn off the power amplifier and activate the LED indicator light on the front panel. The device can use either ac power or a 24v emergency standby pool power and can switch between the two automatically. For emergency evacuation applications, the following functions are monitored: ac power status, battery power status, pilot tone status and amplifier operation status. The LED indicator on the front panel is used to indicate the status of the monitored function. For general public broadcast, the user can turn off the LED indicator light used to indicate pilot sound monitoring and battery status. Each monitored function is equipped with a fail-safe (electrically-closed) relay. These relays are always active regardless of the switch status on the back panel. The input amplifier is equipped with a balanced input with two channel priority control, each with a loop device. This makes it easy to connect to remote systems that require priority control. In addition, an additional 100 V circuit input is provided to connect the amplifier to the 100 V speaker circuit, thus providing greater power for the remote location. Gain or level control is located at the back of the device to avoid unexpected Settings changes. The level meter equipped with LED indicator displays the output level. The output amplifier is equipped with 70v and 100v output for the constant pressure loudspeaker system. Low resistance output is also provided for 8 ohm speaker loads. Amplifier has two separate, according to the priority control of 100 V output, one for only need to enter the area of broadcasting, priorities by another for does not need to pass first enter the area of broadcasting. Controller and the light is positive, the instrument (LED indicator, indicator - 20, to 6, 0 dB and power open), battery operation light, overheat lights, air inlet, for forced air cooling on the back, control input level 1, level 2, the power button, the power switch control input