Bosch PRS-4B125 4-Channel 125W Basic Power Amplifier, Charcoal/Silver

The basic amplifiers are cost effective alternatives to the regular Praesideo power amplifiers, for situations where no built-in digital signal processing functions, such as equalizers, delay and AVC are required. They do not have a Praesideo network connection. Instead, these amplifiers are connected to the Praesideo network via the PRS-16MCI Multi Channel Interface, which provides the basic amplifier with audio signals and has full control. The basic amplifiers are completely supervised and fault events are reported via the multi channel interface to the Praesideo network controller. The basic amplifiers provide connections for separate group A and group B loudspeakers for each zone and support class-A loudspeaker loop wiring. The units should be mounted in a 19" rack with the included mounting brackets.

Amplification
The PRS-4B125 is a four-channel amplifier with 125 W per channel. The power supply is switched mode with low inrush current and the units can run on 48 V, battery stand-by power.

Connection
The amplifiers have built-in output transformers for driving 70 and 100 V loudspeakers. They have separate overload-protected group A and group B loudspeaker connections, which support class-A loop wiring. The separate A and B groups of each channel can be configured for redundancy. The units connect to the PRS-16MCI Multi Channel Interface for audio, control and supervision, but stand-alone operation is possible.

Audio
The amplifiers have analog audio line inputs for low priority local audio. Networked audio from the multi channel interface overrides the local audio.

Security
The units operate both on mains power and on a 48 V battery power supply for emergency back up, with automatic switchover. They supervise both of the power supplies, as well as themselves. They can optionally monitor loudspeakers and their lines, when used together with the PRS-16MCI Multi Channel Interface. Complete channel separation allows one channel of the amplifier to function as a spare amplifier for the other amplifier channel. The amplifier has overload and short circuit protection. An overheat protection circuit switches off the power stage and activates the fault LED on the front panel if the internal temperature reaches a critical limit.

Controls and indicators

Front
• Two two-color LEDs for mains and battery status
• Four amplifier status/level LEDs (per channel)

Back
• Mains on/off switch
• Mains voltage selector
• Rotary volume control for local audio inputs (per channel)

Inside
• 70 V / 100 V selection (per channel)

Interconnection

Back
• Mains socket
• Battery backup input
• Two loudspeaker output screw terminals (per channel)
• Spare amplifier input screw terminal (per channel)
• Two RJ45 connectors (per channel)
• Local audio input screw terminal (per channel)