Bosch has expanded its PRAESENSA IP-based public address and voice alarm system with the introduction of the PRA-EOB end-of-branch device, designed to support supervised multi-branch loudspeaker lines—a key requirement for compliant emergency sound systems.
Fully compliant with EN 54-16, the PRA-EOB was developed to address the realities of retrofit and expansion projects, where loudspeaker lines are often configured in tree or star topologies rather than simple loops. The device is installed at the end of a loudspeaker line, after the final looped-through speaker, enabling reliable supervision in more complex cable layouts.
Beyond branch supervision, the PRA-EOB can also be used to monitor individual loudspeakers. This capability is particularly relevant given that multi-branch configurations are present in approximately 15 percent of typical PAVA installations, especially in facilities that have evolved over time.
Greater flexibility for retrofit environments
By allowing each loudspeaker line branch to be supervised individually, the PRA-EOB enhances system integrity and improves fault detection across non-linear cable topologies. This makes it well suited to buildings where existing infrastructure limits cabling options or where optimising cable lengths is essential.
Supporting multiple supervised branches on a single speaker line can also reduce overall cabling requirements and installation time—an important consideration in retrofit projects where disruption and labour costs must be carefully managed. The device integrates directly into PRAESENSA system supervision, with additional support provided through the PRAESENSA Open Interface API for monitoring and third-party integration.
Addressable pilot tone technology
Rather than relying on impedance measurement, the PRA-EOB uses low-energy, addressable smart pilot tone handshake technology over the existing speaker cable. Each device on a branched line can be individually addressed and monitored without the need for signal thresholds or calibration, simplifying commissioning and long-term maintenance.
Operating above 25 kHz, the pilot tone remains inaudible, ensuring suitability for sensitive environments such as hospitals, hotels, and office spaces. The system is also stable across changing ambient temperatures, supporting consistent performance over time.
Availability
The PRA-EOB end-of-branch device is available and requires the latest PRAESENSA firmware to be installed on existing amplifiers to ensure full compatibility and functionality.
