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Details protection against overload, short circuits, overheat, and battery backup for emergency use.
Describes dual balanced inputs with priority control, loop-through, and 100V slave input.
Details 70V/100V constant voltage and 8-ohm low impedance loudspeaker outputs.
Lists front panel indicators and controls, plus back panel connectors and switches.
Lists safety, immunity, emission, and emergency compliance standards like EN standards.
Lists the amplifier, power cord, mounting brackets, and installation manual.
Details voltage, current, power consumption, frequency response, and distortion metrics.
Covers dimensions, weight, mounting, operating temperatures, and humidity.
Provides a summary of the amplifier and its order number for purchase.
The LBB 1938/20 Plena Power Amplifier is a robust and versatile audio solution designed for a wide range of public address applications. This powerful 480 W amplifier is housed in a 3U high 19-inch case, making it suitable for both rack mounting and tabletop use. Its design emphasizes dependability, ease of use, and comprehensive monitoring, ensuring reliable performance in various environments, including emergency and evacuation systems.
At its core, the LBB 1938/20 serves as a high-performance power amplifier, capable of delivering 480 W of audio output. It is engineered to meet the stringent requirements of public address systems, offering both 70 V and 100 V outputs for constant voltage loudspeaker systems, as well as an 8 ohm output for low impedance loudspeaker loads. This flexibility allows it to integrate seamlessly into diverse audio setups, from small installations to large-scale public address networks.
The amplifier features dual balanced inputs with priority control, a crucial function for managing audio sources in complex systems. Each input includes a loop-through facility, simplifying the connection of remote systems that require priority control. An additional 100 V line input is provided, enabling the amplifier to connect directly to a 100 V loudspeaker line. This feature is particularly useful for expanding power to remote locations or integrating into existing 100 V distributed audio systems.
For emergency and evacuation scenarios, the LBB 1938/20 incorporates extensive monitoring capabilities. It continuously supervises critical functions such as mains presence, battery presence, pilot tone presence, and amplifier operation. The status of these supervised functions is clearly indicated by LEDs on the front panel, providing immediate visual feedback to operators. Failsafe (normally energized) relays are also provided for each supervised function, ensuring that critical alerts are always active, regardless of rear panel switch settings. This makes the amplifier compliant with safety standards like EN 54-16 and EN 60849, essential for life safety applications.
The amplifier also includes two separate priority-controlled 100 V outputs. This allows for the creation of distinct zones: one for announcements made exclusively via the priority input, and another for zones that should not receive announcements from the priority input. This zoning capability enhances control and allows for tailored audio distribution based on specific application requirements.
The LBB 1938/20 is designed for straightforward operation and integration. The front panel provides clear visual indicators for the amplifier's status, including power, audio output level, and supervised functions. An LED-bar meter displays the output level, allowing for quick monitoring of audio activity. The gain or level control is conveniently located on the rear of the unit, a deliberate design choice to prevent accidental setting changes during operation.
The unit's ability to operate on both mains power and a 24 V battery power supply with automatic switchover ensures continuous operation, even during power outages. This feature is vital for emergency systems where uninterrupted audio is paramount. The battery status is monitored, and an LED indicator on the front panel provides feedback on its presence. For general public address use, the LEDs for pilot tone supervision and battery status can be switched off, reducing visual clutter when not required.
The dual inputs with priority switching allow for sophisticated audio routing. Input 1 is designated as the priority input, enabling it to override other audio sources when activated. This is particularly useful for emergency announcements, paging, or other critical messages that need to take precedence. The loop-through facility on both inputs simplifies system expansion and integration with other audio equipment.
The amplifier's versatile output options (70 V, 100 V, and 8 ohm) make it adaptable to various loudspeaker configurations. Whether connecting to distributed loudspeaker lines or direct low-impedance speakers, the LBB 1938/20 provides the necessary power and connectivity.
Dependability is a key aspect of the LBB 1938/20's design. The amplifier incorporates several features to ensure long-term reliability and ease of maintenance. It is protected against overload and short circuits, safeguarding the internal components from potential damage due to electrical faults.
A temperature-controlled fan system is integrated to manage internal heat, ensuring high reliability even at high output levels. This fan operates with low acoustic noise at lower output levels, making the unit suitable for environments where quiet operation is desired. In the event that the internal temperature reaches a critical limit due to poor ventilation or overload, an overheat protection circuit automatically switches off the power stage and activates an LED on the front panel. This proactive measure prevents damage to the amplifier and alerts operators to potential issues.
The comprehensive monitoring of mains presence, battery presence, pilot tone presence, and amplifier operation provides valuable diagnostic information. Should any of these functions fail, the corresponding LED indicators and failsafe relays will activate, allowing for prompt identification and resolution of issues. This level of supervision simplifies troubleshooting and helps maintain the integrity of the public address system.
The robust construction and adherence to international safety and emission standards (EN 60065, EN 50130-4, EN 55103-1) further contribute to the amplifier's maintainability and long operational life. The design allows for easy rack mounting, facilitating access for installation and servicing. The inclusion of an installation and user instruction manual provides clear guidance for setup, operation, and basic troubleshooting, empowering users to manage the device effectively.
General| Number of Channels | 1 |
|---|---|
| Damping factor (at 1 kHz) | >100 |
| Priority input | Yes |
| TEL. / 100 V input | Yes |
| Loop-through output | Yes |
| Nominal level loop-through output | 0 dBu |
| Headphones output | Yes |
| Power Supply | 100 - 240 V AC, 50/60 Hz |
| Mains voltage | 100 - 240 V AC, 50/60 Hz |
| S/N (flat, max. gain, rated output) | > 70 dB |
| Signal-to-Noise Ratio | > 70 dB |
| Ambient temperature | 0 °C to +45 °C |
| Storage temperature | +70 ºC |
| Output Impedance | 8 ohm |
