BOSCH LBB1925/10 Plena 6 Zone Pre-Amplifier

Description

The Bosch LBB1925/10 Plena 6 zone pre-amplifier fulfils a wide variety of public address requirements at a surprisingly low cost. It can provide dual channel operation for simultaneous calls and BGM for up to six different zones using two Plena amplifiers or single channel operation using one amp.

Two input channels are provided for paging microphone call stations, a universal input for mic / line with speech optimized tone control and 3 inputs for BGM selection optimized for music.

Background music and call station zone selection is on the front of the LBB1925/10.

The microphone input has a selectable speech filter for improved intelligibility, a volume control, and bass and treble tone controls with shelving characteristics optimized for speech. The call channel is available on the balanced XLR master output.

The BGM channel provides three inputs on stereo cinch-connectors, converted to mono, with front panel selection, volume control and bass and treble tone controls with shelving characteristics optimized for music. The BGM channel has a direct output on balanced XLR for dual channel operation. It can also feed the master output, with the lowest priority, for single channel operation. Zone selector switches on the front panel control the BGM routing. An overload protected 24 VDC output provides power for driving external relays, often making an external power supply unnecessary.

Each zone has a tri-state control on the front panel that can turn it off, switch it to the call channel, or to the BGM channel. The all‐call microphone input and emergency activation override the call station selection on the call channel. Each zone has separate priority overrides with preset volume levels.

This assures an appropriate message volume, independent of any local volume settings, such as for BGM. Both three‐wire and four‐wire override schemes are supported. An override also activates a voltage-free contact (call-active) available for external control and monitoring. The master output channel, or one of the input channels, can be monitored through the headphone connector and/or the LED VU‐meter.