Plena feedback suppressor - LBB 1968/00
  • Patented feedback suppression algorithm
  • Suppresses feedback before it occurs
  • Automatically adapts to the acoustic situation
  • Up to 12dB additional gain before feedback occurs
  • Balanced line or microphone input with phantom power supply
  • Second microphone input with automatic mixer
Plena feedback suppressor LBB 1968/00
Plena feedback suppressor (LBB 1968/00) - datasheet
Plena feedback suppressor (LBB 1968/00) - installation and operating manual
Plena feedback suppressor (LBB 1968/00) - application sheet - places of worship

The Plena feedback suppressor uses a powerful DSP with a revolutionary patented algorithm to supress acoustic feedback. It eliminates feedback by actively filtering out the unwanted room reverb that leads to feedback using an echo cancellation and de-reverberation algorithm. By adding masked, inaudible noise to the output signal or by shifting the frequency of output signal by 5Hz, 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.

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 acoustic environment is more stable. The adaptive filter is allowed to converge more slowly to suppress the reverb components even more. Depending on the acoustic environment and the chosen mode of operation up to 12dB 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 or a pulpit or conference table, the 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. This way it 'tracks' the moving speaker for optimum speech intelligibility, and the maximum feedback margin is maintained by keeping the summed gain constant. Even when the feedbacksuppressor is switched to 'bypass', the automatic mixer function remains operational.

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