Bosch Plena Power Amplifier LB1935 Installation And User Instructions Manual

Communications Systems | LBB 1930/20 Plena Power Amplifier
LBB 1930/20 Plena Power Amplifier
The LBB 1930/20 is a powerful 120 W power amplifier in a
2U 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.
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.
The unit operates both on mains power and on a 24 V
battery power supply for emergency back up, with
automatic switchover.
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 battery status can be switched
off for general public address use. Failsafe (normally
▶ 120 W power amplifier in a compact housing
▶ 70 V / 100 V and 8 ohm outputs
▶ Dual inputs with priority switching
▶ 100 V input for slave operation on 100 V speaker line
▶ Temperature controlled forced front to back
ventilation, directly stackable.
▶ Mains, battery back-up and pilot tone supervision
▶ EN 54‑16 and EN 60849 compliant
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.
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 LBB 1930/20 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 receive
announcements made via the priority input.
Controls and indicators
Front
•
Meter (LED's for -20, -6, 0 dB and Power ON)
•
Battery operation indicator
•
Overheat indicator
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