Bosch LBB 1968 Manual de usuario descargar pdf (Pagina 21)

48 | Plena Range

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Communication

LBB 1968/00 Plena Feedback

Suppressor

The LBB 1968/00 Plena feedback suppressor uses a powerful

DSP with a revolutionary patented algorithm to suppress

acoustic feedback. It eliminates feedback by actively filtering out

the unwanted room reverb using an echo-cancellation and de-

reverberation algorithm. By adding masked (inaudible) noise to

the output signal or by shifting the frequency of the output signal

by 5 Hz, the Plena feedback suppressor is able to detect the

reverb component of the signal and remove it before feedback

occurs, leaving the original signal intact.

Features

• Patented feedback suppression algorithm

• Suppresses feedback before it occurs

• Automatically adapts to the acoustical situation

• Up to 12 dB additional gain before feedback occurs

• Balanced line or microphone input with phantom supply

• Second microphone input with automatic mixer

Functions

The adaptive filter can be switched between fast mode and

accurate mode. The fast mode is for situations where the

microphone position changes over time, like in a discussion

system with multiple switching microphones. The accurate mode

is for situations with a fixed microphone position, such as on a

pulpit where the acoustical environment is more stable. The

adaptive filter is allowed to converge more slowly to suppress

the reverb components even more.

Depending on the acoustical environment and the chosen mode

of operation, up to 12 dB of additional gain is possible before

acoustic feedback occurs. The Plena feedback suppressor also

features a built-in automatic mixer for the two microphone inputs.

In many situations, like on a rostrum, pulpit or conference table,

two microphones are used to better capture the voice of a

moving speaker, although this often increases the risk of

acoustic feedback.

To counter this, the automatic mixer in the Plena feedback

suppressor automatically reduces the gain of the microphone

with the lowest signal input, and increases the gain of the

microphone with the highest signal input. In this way it ‘tracks’

the moving speaker for optimum speech intelligibility and the

maximum feedback margin is maintained by keeping the

summed gain constant. The automatic mixer function remains

operational even when the feedback suppressor is switched to

‘bypass’.

Parts Included

Certifications and Approvals

Quantity Components

1 LBB 1968/00 Plena Feedback Suppressor

1 19“ mounting brackets

1 Power cord

EMC emission acc. to EN 55103-1

EMC immunity acc. to EN 55103-2

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Bosch LBB 1968 Manual de usuario Pagina 21

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