Bosch LBB 1912/10 - User Manual

Communications Systems | LBB 190x/10 and LBB 191x/10 Plena Mixer Amplifiers
The Plena mixer amplifier is a versatile, high-performance
unit with four mono microphone inputs and a music input.
It fulfills a wide variety of public address requirements at
a surprisingly low cost.
Functions
All input channels have a phantom power supply to
provide power to condenser microphones and selectable
speech filters for improved intelligibility. Input channels 3
and 4 can also be switched to line sensitivity. Separate
music inputs are available with their own input selector
and volume control.
Input channel 1 can take priority over all other
microphone and music inputs. Contact closure on the 5-
pin DIN connector, or if the signal level on channel 1
exceeds a predefined value (VOX) will activate priority. A
2-tone chime can be configured to precede a priority
announcement. A telephone or emergency input with VOX
activation and its own preset volume control overrides all
other input.
Loop through input and output connections enable
external sound processing equipment, such as an
equalizer or the Plena feedback suppressor, to be
connected between the preamplifier and the power
amplifier stages. An LED VU-meter monitors the master
output. The unit also has a tape output channel.
The Plena mixer amplifiers come in a range of maximum
output power. This power is directly available on 70 V and
100 V constant voltage connections and on a low
impedance connection for an 8 ohm load. Moreover, the
amplifiers have a separate 70 V / 100 V call-only output
channel for addressing areas where only priority
announcements are required, and a 70 V / 100 V mix-only
output channel for areas where no priority
announcements should be heard. The call-only output can
also be used for 3-wire remote, volume control override.
For more output power than the built-in power stage can
deliver, additional Plena power amplifiers can be
connected to the balanced line output in a loop-through
arrangement.
The LBB 1914/10 offers the same functionality as the
LBB 1912/10 but also has two front-panel switches to
direct the amplifier output to two separate zones. This is
useful when certain announcements or background music
should not be heard in part of a building. Priority calls,
however, are always routed to both zones.
LBB 190x/10 and LBB 191x/10 Plena
Mixer Amplifiers
▶
Range of single and dual zone mixer amplifiers from
30 W to 120 W
▶
Four low-noise balanced inputs for microphone or line
▶
Selectable priority & VOX switching on microphone
input 1
▶
Optional 2-tone chime to precede announcements
▶
VOX activated emergency override
▶
Outputs for normal, call-only and mix-only zones
▶
Choice of CD, tuner or auxiliary music inputs
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Bosch LBB 1912/10 Specifications

General

S/N (flat @ max. volume)	> 70 dB
Mains Voltage	230 V AC
S/N (flat @ rated volume)	> 75 dB
Signal-to-Noise Ratio	> 70 dB
Line Output	Yes
Operating Temperature	-10 ºC to +45 ºC (14 ºF to +113 ºF)
Storage Temperature	-20°C to +70°C

Summary

Functions

Controls and Indicators

Front Panel

Lists front panel controls, including power, volume, and source selection.

Rear Panel

Details rear panel controls for inputs, outputs, and power settings.

Interconnections

Explains the various input/output connection points on the unit.

Parts Included

Certifications and Approvals

Installation;Configuration Notes

Ordering Information

Important Safeguards

About This Manual

Conventions

Explains symbols, warnings, and notes used throughout the manual.

Safety Precautions

Provides essential safety warnings and advice for safe operation and handling.

Internal Settings

Setting Chime Volume

Adjusts the volume of the chime attention signal preceding a priority call.

Setting Output Voltage (LBB1903;1906;1912)

Configures output voltage for 70V, 100V, or 8 Ohm outputs on specific models.

Setting Output Voltage (LBB1914)

Configures output voltage for 70V, 100V, or 8 Ohm outputs on LBB1914 model.

Rack Installation

External Settings and Connections

Priority Microphone Connection

Details connecting a priority microphone via DIN or 6.3mm jack for voice-controlled priority.

Chime ON;OFF Switch

Describes the switch for activating the chime function before an announcement.

Microphone Inputs

Explains connection options for microphone inputs using XLR or 6.3mm jack.

Emergency Input

Covers connection and priority settings for the emergency input.

Music Source Inputs

Instructions for connecting external music sources like CD players or tuners.

Connecting Line Output

Details connecting additional PA amplifiers to the line output.

Connecting Loudspeakers

Guides on connecting constant voltage and low impedance speakers.

Low Impedance Loudspeakers

Instructions for connecting 8 Ohm loudspeakers to the unit.

Mains Connection

How to connect the unit to the mains power supply using the provided cord.

Mixer Amplifier Operation

Source Selection

Using the music source selector and input volume controls for balancing audio.

Volume and Tone Control

Adjusting the master volume and the treble/bass tone controls.

Zone Selection (LBB1914;10)

Routing audio mix to specific zones on the LBB1914/10 model.

Technical Data

Electrical Specifications

Covers mains voltage, inrush current, and battery power specifications.

Performance Specifications

Details frequency response, distortion, and tone control ranges.

Input Specifications

Specifications for all input types, including sensitivity and impedance.

Output Specifications

Details nominal levels and impedance for master, tape, and interconnection outputs.

Environmental Conditions

Specifies operating and storage temperature ranges and humidity limits.

General Specifications

Covers EMC, acoustic noise level, dimensions, and weight.