Bosch LBB 1903 Single Zone 30W Mixing Amplifier


The Plena mixer amplifier is a versatile, high-performance unit with four mono microphone inputs and a music input.
It fulfills a wide variety of public address requirements at a surprisingly low cost.

All input channels have a phantom power supply to provide power to condenser microphones and selectable speech filters for improved intelligibility. Input channels 3 and 4 can also be switched to line sensitivity. Separate music inputs are available with their own input selector and volume control.
Input channel 1 can take priority over all other microphone and music inputs. Contact closure on the 5-pin DIN connector, or if the signal level on channel 1 exceeds a predefined value (VOX) will activate priority. A 2-tone chime can be configured to precede a priority announcement. A telephone or emergency input with VOX activation and its own preset volume control overrides all other input. Loop through input and output connections enable external sound processing equipment, such as an equalizer or the Plena feedback suppressor, to be connected between the preamplifier and the power amplifier stages. An LED VUmeter monitors the master output. The unit also has a tape output channel. The Plena mixer amplifiers come in a range of maximum output power. This power is directly available on 70 V and 100 V constant voltage connections and on a low impedance connection for an 8 ohm load. Moreover, the amplifiers have a separate 70 V / 100 V call-only output channel for addressing areas where only priority
announcements are required, and a 70 V / 100 V mix-only output channel for areas where no priority announcements should be heard. The call-only output can also be used for 3-wire remote, volume control override. For more output power than the built-in power stage can deliver, additional Plena power amplifiers can be connected to the balanced line output in a loop-through arrangement.

  • Model: LBB1903/10
  • Shipping Weight: 10 kgs
  • Manufactured by: Bosch
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