Communications Systems | LBB 1938/20 Plena Power Amplifier
LBB 1938/20 Plena Power Amplifier
u 480 W power amplifier in a 3U high 19”housing
u EN 54‑16 certified and EN 60849 compliant
u 70 V / 100 V and 8 ohm outputs
u Dual inputs with priority switching
u 100 V input for slave operation on 100 V speaker
line
The LBB 1938/20 is a powerful 480 W power amplifier
in a 3U high 19”case for rack mounting or tabletop
use. LEDs on the front panel show the status of the
amplifier: power, audio output level, and supervised
functions. This high-performance unit fulfills a wide
range of public address requirements at a surprisingly
low cost.
battery status can be switched off for general public
address use. Failsafe (normally energized) relays are
provided for each supervised function. These relays
are always active regardless of the switches on the
rear panel.
Input
The system has two balanced inputs with priority
control, each with a loop-through facility. This makes it
easy to connect remote systems that require priority
control. An additional 100 V line input is provided to
connect the amplifier to a 100 V loudspeaker line, to
provide more power to remote locations.
Functions
Dependability
The amplifier is protected against overload and short
circuits. A temperature-controlled fan ensures high
reliability at high output levels and low acoustic noise
at lower output levels. An overheat protection circuit
switches off the power stage and activates an LED on
the front panel, if the internal temperature reaches a
critical limit due to poor ventilation or overload.
Gain or level control is located on the rear of the unit
to avoid accidental setting change. A meter with LED-
bar shows the output level.
Output
The amplifier has 70 V and 100 V outputs for constant
voltage loudspeaker systems and a low impedance
output for 8 ohm loudspeaker loads.
The unit operates both on mains power and on a 24 V
battery power supply for emergency back up, with
automatic switchover.
The LBB 1938/20 has two separate priority controlled
100 V outputs for zones that only need
announcements made via the priority input, and for
zones that will not get any announcements made via
the priority input.
For emergency and evacuation use, the following
functions are monitored: mains presence, battery
present, pilot tone presence, amplifier operation.
Front panel LEDs indicate the status of supervised
functions. The LEDs of pilot tone supervision and
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3 | LBB 1938/20 Plena Power Amplifier
-3 dB
26 A (625 W)
18 A (430 W)
3.8 A (91 W)
0.7 A (17 W)
-6 dB
Pilot tone*
Idle
* 20 kHz -20dB with maximum loudspeaker load
Mechanical
Dimensions (H x W x D)
145 x 430 x 370 mm
(19" wide, 3U high, with feet)
Weight
Mounting
Color
Approx. 25 kg
Standalone, 19”rack
Charcoal
Environmental
Operating temperature
Storage temperature
-10 ºC to +55 ºC (14 ºF to +131 ºF)
-40 ºC to +70 ºC (-40 ºF to
+158 ºF)
Relative humidity
<95%
Acoustic noise level of fan
<48 dB SPL @ 1 m (max output)
Ordering information
LBB 1938/20 Plena Power Amplifier
480 W power amplifier in a 3U high 19”case for rack
mounting or tabletop use.
Order number LBB1938/20
Represented by:
Americas:
Europe, Middle East, Africa:
Bosch Security Systems B.V.
P.O. Box 80002
5617 BA Eindhoven, The Netherlands
Phone: + 31 40 2577 284
Fax: +31 40 2577 330
Asia-Pacific:
Robert Bosch (SEA) Pte Ltd, Security
Systems
11 Bishan Street 21
Singapore 573943
Phone: +65 6571 2808
Fax: +65 6571 2699
China:
America Latina:
Bosch Security Systems, Inc.
12000 Portland Avenue South
Burnsville MN 55337, USA
Phone: +1-800-392-3497
Fax: +1-800-955-6831
Bosch (Shanghai) Security Systems Ltd. Robert Bosch Ltda Security Systems Division
201 Building, No. 333 Fuquan Road
North IBP
Changning District, Shanghai
200335 China
Phone +86 21 22181111
Fax: +86 21 22182398
Via Anhanguera, Km 98
CEP 13065-900
Campinas, Sao Paulo, Brazil
Phone: +55 19 2103 2860
Fax: +55 19 2103 2862
© Bosch Security Systems 2012 | Data subject to change without notice
1889273995 | en, V2, 24. Nov 2012
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