There are four types of power amplifier units in the Praesideo product range. These differ in the number of amplifier channels per frame: one two four or eight. The overall power rating is 500 watts for all of the amplifiers.

The power amplifiers can be set to 100 V 70 V and 50 V output tappings. They have short-to-ground and shortcircuit detection functions and can generate their own pilot tone for supervision purposes.

Functions

The power amplifiers receive input signals over the network. They also have two auxiliary audio inputs (four for LBB 4428/00) for local audio. Their eight control inputs are freely programmable for system actions and priorities can be assigned to these inputs. Each control input has the ability to monitor the attached line for open and shortcircuits.
Control outputs are freely programmable for faults and call related actions.

The 2 x 16-character display and the rotary control enable local status enquiries. The display shows the VU-meter reading when the audio monitoring mode is active. Audio can be monitored by headphone.

The units are self-monitoring and continually report their status to the network controller. They support both single branch and redundant loop cabling. The amplifiers have a changeover facility for spare power amplifier switching. Changeover relays are included with the units. The amplifiers have a 48 V DC back-up supply input.

The digital audio processing can handle three parametric equalization sections and two shelving equalization sections per channel with configurable audio delay.

1 2 4 or 8 audio outputs (selection from 100 / 70 / 50 V outputs)
• Audio processing and delay for each amplifier channel
• Amplifier supervision and spare amplifier switching
• Loudspeaker line and loudspeaker supervision (LBB 4428/00 only line supervision)
• Eight control inputs and 1 2 4 or 8 control outputs
• Supervision of line attached to control inputs
• Automatic volume control
• Two audio inputs (4 audio inputs for LBB 4428/00)
• Redundant network connection