The fast route to safety
PLENA Public Address and Voice Alarm System
PLENA voice alarm components
LBB1938/30 PLENA 480 W Power Amplifier
480 W amplifier for the PLENA Voice Alarm System: 70 V / 100 V and 8 ohm outputs, dual inputs with priority switching, EN 54-16 certified.
- 480 W Output
- 70 V / 100 V and 8 Ohm
- EN 54-16 Certified
The fast route to safety
PLENA Public Address and Voice Alarm System
PLENA voice alarm components
LBB1938/30 PLENA 480 W Power Amplifier
480 W amplifier for the PLENA Voice Alarm System: 70 V / 100 V and 8 ohm outputs, dual inputs with priority switching, EN 54-16 certified.
- 480 W Output
- 70 V / 100 V and 8 Ohm
- EN 54-16 Certified
BOSCH · PLENA VOICE ALARM
Bosch LBB1938/30 Front & Rear Panels
Switch between the front and rear views of the amplifier. Select Zoom to read the labelled indicators and connections.
Front panel
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Front Panel Overview
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- Output level meter
- Check the amplifier’s output level at −20, −6 and 0 dB.
- Status indicators
- See pilot-tone, battery and mains status, plus the overheat warning.
- Cooling air inlet
- The lower grille is the air intake for the amplifier’s cooling system.
Rear panel
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Rear Panel Overview
2 / 2
- Audio inputs
- Find the priority and program XLR inputs, their level controls and loop-through connections.
- Loudspeaker outputs
- Identify the direct and priority-controlled loudspeaker terminals.
- Power and supervision
- Locate the mains inlet, 24 V DC backup input, fault relay and detection switches.
BOSCH · PLENA VOICE ALARM
Bosch LBB1938/30 Front & Rear Panels
Switch between the front and rear views of the amplifier. Select Zoom to read the labelled indicators and connections.
Front panel
Zoom
Front Panel Overview
1 / 2
- Output level meter
- Check the amplifier’s output level at −20, −6 and 0 dB.
- Status indicators
- See pilot-tone, battery and mains status, plus the overheat warning.
- Cooling air inlet
- The lower grille is the air intake for the amplifier’s cooling system.
Rear panel
Zoom
Rear Panel Overview
2 / 2
- Audio inputs
- Find the priority and program XLR inputs, their level controls and loop-through connections.
- Loudspeaker outputs
- Identify the direct and priority-controlled loudspeaker terminals.
- Power and supervision
- Locate the mains inlet, 24 V DC backup input, fault relay and detection switches.
Key specs
- Rated output: 480 W RMS
- Speaker outputs: 70 V / 100 V / 8 Ω
- Audio inputs: 2 balanced XLR inputs with priority switching
- Expansion input: 100 V loudspeaker line input
- Backup power: 24 V DC with automatic switchover
- Certification: EN 54-16
Bosch LBB1938/30 Technical Specifications
The Bosch LBB1938/30 is a 480 W RMS PLENA power amplifier with balanced XLR inputs, priority switching, and outputs for 70 V, 100 V, and 8 Ω loudspeaker systems.
Electrical
| Specification | Value |
|---|---|
| Mains supply | 220/230 V AC, ±10%, 50/60 Hz |
| Mains inrush current | 19 A |
| Maximum apparent power | 2,200 VA |
| Backup supply voltage | 24 V DC, ±15% |
| Battery supply maximum current | 30 A, as listed under Battery Power Supply |
| Backup switchover | Automatic when mains power fails and a backup supply is connected |
Amplifier Performance
| Specification | Value |
|---|---|
| Rated output power | 480 W RMS |
| Maximum output power | 720 W |
| Output reduction on backup power | −1 dB |
| Frequency response | 50 Hz to 20 kHz (+1/−3 dB at −10 dB relative to rated output) |
| Distortion | <1% at rated output power, 1 kHz |
| Signal-to-noise ratio | >90 dB at maximum volume, flat |
Audio Inputs
| Specification | Value |
|---|---|
| Balanced line inputs | 2 × 3-pin XLR |
| Input assignment | Input 1 for priority audio, Input 2 for programme audio |
| Line input sensitivity | 1 V |
| Line input impedance | 20 kΩ |
| Line input common-mode rejection | >25 dB from 50 Hz to 20 kHz |
| Line input gain | 40 dB |
| 100 V line input | Unbalanced screw terminals for connection to a 100 V loudspeaker line |
| 100 V input sensitivity | 100 V |
| 100 V input impedance | 330 kΩ |
Audio Outputs
| Specification | Value |
|---|---|
| Line loop-through outputs | 2 × 3-pin XLR, each directly connected to its respective line input |
| Loop-through nominal level | 1 V |
| Loudspeaker outputs | 3 output groups with floating screw terminals |
| Direct loudspeaker output | 100 V, 70 V, or 8 Ω |
| Priority-only output | Carries priority audio from Input 1. Internally selectable for 100 V or 70 V. |
| Non-priority output | Carries programmed audio without priority calls. Internally selectable for 100 V or 70 V. |
Controls, Supervision and Protection
| Specification | Value |
|---|---|
| Rear-panel control terminals | Input 1 priority control and Input 2 enable |
| Rear-panel level adjustment | Separate level controls for Inputs 1 and 2 |
| Front-panel output meter | LEDs at −20 dB, −6 dB, and 0 dB |
| Front-panel status indicators | Power, pilot tone, battery, mains, and overheat |
| Supervised functions | Mains supply, backup battery, pilot tone, and amplifier operation |
| Fault signalling | Normally energized fail-safe relays |
| Amplifier protection | Overload, short circuit, and thermal shutdown |
| Cooling | Temperature-controlled fan with a front air inlet |
Power Consumption
| Specification | Value |
|---|---|
| AC operation, maximum | 990 W |
| AC operation at −3 dB / −6 dB | 715 W / 510 W |
| AC operation with pilot tone / idle | 110 W / 25 W |
| 24 V DC operation, maximum | 32 A (770 W), as listed under Power Consumption |
| 24 V DC operation at −3 dB / −6 dB | 26 A (625 W) / 18 A (430 W) |
| 24 V DC operation with pilot tone / idle | 3.8 A (91 W) / 0.7 A (17 W) |
| Pilot-tone test condition | 20 kHz at −20 dB with maximum loudspeaker load |
Mechanical
| Specification | Value |
|---|---|
| Dimensions (H × W × D) | 145 × 430 × 370 mm, including feet |
| Mounting | 19-inch rack or tabletop |
| Rack height | 3U |
| Weight | Approx. 25 kg |
| Colour | Charcoal |
Environmental
| Specification | Value |
|---|---|
| Operating temperature | −10 °C to +55 °C |
| Storage and transport temperature | −40 °C to +70 °C |
| Relative humidity | <95% |
| Fan noise | <48 dB SPL at 1 m at maximum output |
Standards
| Specification | Value |
|---|---|
| Voice alarm certification | EN 54-16 |
| Safety | EN 60065 |
| Immunity | EN 50130-4 |
| Emissions | EN 55103-1 |
Questions & answers
Know before you buy
Quick answers about the LBB1938/30, and how it compares.
What is the Bosch LBB1938/30?
The Bosch LBB1938/30 is a 480 W RMS PLENA power amplifier for public address and voice alarm systems. It powers loudspeakers for paging, background music, and emergency announcements.
Which loudspeakers can I connect to the Bosch LBB1938/30?
It supports 70 V and 100 V constant-voltage loudspeaker systems, as well as 8 Ω low-impedance loads. The output must match the connected loudspeaker system.
Can the Bosch LBB1938/30 work with the PLENA LBB1990/00 controller?
Yes. Bosch lists the LBB1938/30 as an external power amplifier for the PLENA Voice Alarm System. It can add loudspeaker power to a system built around the LBB1990/00 controller.
What is the difference between the Bosch LBB1938/30 and LBB1935/20?
The LBB1938/30 delivers 480 W RMS and occupies 3U of rack space. The LBB1935/20 delivers 240 W RMS and occupies 2U. Choose between them based on the loudspeaker load and available rack space.
Can the LBB1938/30 keep working during a power outage?
Yes. With a suitable external 24 V DC backup supply connected, the amplifier switches to backup power automatically if mains power fails.
Can the LBB1938/30 extend an existing 100 V loudspeaker system?
Yes. Its dedicated 100 V line input accepts audio from an existing 100 V loudspeaker line. The amplifier can then drive a separate loudspeaker load in another area.
Who is the authorized Bosch distributor in Pakistan?
ESCO (Electronic Security Company) is an authorized Bosch distributor in Pakistan. Contact ESCO for the current Bosch LBB1938/30 price and availability or to request a project quotation.