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The Bosch LBB 1925/10 Plena 6 zone pre-amplifier fulfills a wide variety of public address requirements at a surprisingly low cost. It can provide dual channel operation for simultaneous calls and BGM for up to six different zones using two Plena amplifiers or single channel operation using one amp.

Two input channels are provided for paging microphone call stations, a universal input for mic / line with speech optimized tone control and 3 inputs for BGM selection optimized for music.

Background music and call station zone selection is on the front of the LBB1925/10.


  • 6 zone system pre-amplifier, with single or dual channel operation
  • Two input channels for call stations
  • Universal input for microphone/line, with speech optimized tone control
  • Allows multiple 6 zone call stations to be daisy-chained
  • Separate music and call channels with dedicated tone controls
  • 6 levels of priority available
  • Routable Music to zones
  • Emergency/telephone input
  • 24v override output on each zone
  • Selectable alarm tone, time signal and chimes
  • 3 separate BGM inputs and music optimized tone control
  • Further Mic/line input
  • Headphone monitor
  • VU meter
  • 19" mounting brackets included
  • 2U high

Additional Information


Mains Voltage

230 VAC / 115VAC, ±15%, 50 / 60 Hz

Max Mains Power Consumption

25 VA

Battery Voltage

24 VDC, +20%/-10%

Max Battery Current


Max Mains Inrush Current

1.5 A @ 230 Vac / 3 A @ 115 VAC


Frequency Response

50 Hz – 20 kHZ (+1/-3dB)

Bass Control

±10 dB @ 100 Hz

Treble Control

±10 dB @ 10 kHz


Mic Input


1 mV (microphone), 200 mV (line)


>1 kOhm (mic.), >5 kOhm (line)

S/N (flat at max volume)

>63 dB (mic.), >70 dB (line)

S/N (flat at min volume/muted)

>75 dB


>40 dB (50 Hz – 20 kHz)

Phantom Power Supply

16 V via 1.2 kOhm, in mic. Mode only

3 Cinch inputs (unbalanced, stereo converted to mono)


200 mV


22 kOhm

S/N (flat at max volume)

>70 dB

S/N (flat at min volume/muted)

>75 dB


Master Output

3-pin XLR, balanced

Music Output

3-pin XLR, balanced

Tape Output

Cinch, 2 x mono

Headphone output

6.3mm jack stereo, signal mono

Interconnection/emergency input

3-pin XLR, balanced

Interconnection output

3-pin XLR, balanced



Dimensions (H x W x D)

100 x 430 x 270 mm (19" wide, 2U high)



19" Mounting Brackets



Approx. 5 kg

View FileWhy An Impedance Meter is Essential for Audio Installers    Size: (72.64 KB)
View FileBosch LBB 1925/10 Pre-Amp Mixer    Size: (489.25 KB)
View FileEC Declaration of Conformity: Bosch LBB1925/10, LBB1941/00, LBB1946/00    Size: (716.67 KB)
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