Bosch LBC 3951/11 User Manual

Communication | LBC 3951/11 Ceiling Loudspeaker

LBC 3951/11
Ceiling Loudspeaker

• Compact yet powerful

• Very wide opening angle

• Modern unobtrusive styling

• Installation friendly

• Splash - waterproof

• Comply with international
installation and safety regulations

With this loudspeaker, Bosch provides impressive audio
performance at an economical price. The 9 W (maximum
power) ceiling loudspeaker is suitable for indoor public
address installations, particularly in applications with smaller
areas such as hotel rooms, shops, offices and elevators.

Functions

The LBC 3951/11 has a perforated metal grille with a plastic
surround, finished in an attractive off-white RAL color. The
unobtrusive styling of this loudspeaker complements today’s
interior lighting.
The loudspeaker feature a very wide opening angle, which
means fewer units are required to cover a given area. The wide
frequency range means better speech and music reproduction.
The unit is supplied with a 100 V matching transformer with
taps on the primary winding for full-power, half-power,
quarter-power and eighth-power radiation.
The loudspeaker (with special treated paper cone), is IPx4
water protected from the front and can be applied in humidity
environments for example bathrooms, sauna’s, atriums and
swimming pool areas.

Parts Included

Certifications and Approvals

All plastic parts are manufactured from self-extinguishing
high-impact ABS material (according to UL 94V0
All Bosch loudspeakers are designed to withstand operating at
their rated power for 100 hours in accordance with IEC 268-5
Power Handling Capacity (PHC) standards. Bosch has also
developed the Simulated Acoustical Feedback Exposure
(SAFE) test to demonstrate that they can withstand two times
their rated power for short durations. This ensures extra
reliability under extreme conditions, leading to higher
customer satisfaction, longer operating life, and much less
chance of failure or performance deterioration.

Quantity Component

1 LBC 3951/11 Ceiling Loudspeaker

Safety EN 60065

Water Protected Acc. To EN 60529 IP x 4

2 | LBC 3951/11 Ceiling Loudspeaker

Installation/Configuration Notes

Installation is made easy with integral clips that securely hold
the ceiling loudspeaker in its cut-out. Ceilings from 9 to 25
mm thick can be accommodated. A template is also provided
for accurately marking the cutout in ceiling panels. Wiring is
via a connection block with push-type terminals, making
installation possible without using any special tools. The
terminal blocks have provision for loop-through wiring. The
transformer is delivered wired for 6 W rated output power, but
can easily be changed for other connections using the color­coded wires and terminal block.

Dimensions in mm (inch)

Circuit diagram

Frequency response

Polar diagram

Quick reference table

01 Clamp

02 Matching Transformer

03 Terminal Block

X

Y

Z

Octave
band (Hz)

125 250 500 1k 2k 4k 8k

SPL 1.1 87 87 85 88 89 89 86

SPL max. 95 95 93 96 97 97 94

Q-factor 4 5.6 2.2 3.2 4.6 10.7 19

Efficiency 0.16 0.11 0.18 0.25 0.22 0.09 0.03

H. angle 18 0 18 0 180 17 0 16 0 80 60

V. angle 18 0 180 18 0 17 0 16 0 80 60