Troubleshooting guide

Modular Processors
SHURE
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P4800 System Processor Software Guide Page 56 of 108
Digital Feedback Reducer (DFR)
The DFR uses Shure's patented Adaptive Notch Filter algorithm to automatically detect feedback and deploy
narrow-band notch filters. The System Processor provides the following types of DFR:
Block Name Description
§ DFR5 5 Band Digital Feedback Reducer
§ DFR10 10 Band Digital Feedback Reducer
Function
Use the DFR as the initial processor on any input channel that receives signal from a live microphone
where feedback is problematic. Each time it detects feedback, the DFR activates a dynamic filter. It
begins by inserting a −3 dB, 1/10-octave notch filter at the feedback frequency. It then increases the
filter depth in 3 dB increments, up to −18 dB, until the feedback stops. You can also allocate fixed
filters at specific room nodes. When the DFR detects feedback at the frequency of a fixed filter, it
deepens that notch with a dynamic filter.
Parameter Window Features
This section explains the features and parameter controls of the digital feedback reducer using the
DFR10 as the example, as pictured above in figure 40. The features of the DFR5 are identical, aside
from the number of notch filters available.
Response Graph
This curve is a graphical representation of the combined results of the processor's active notch filters
(highlighted in yellow).
Note: The curve does not reflect the accumulated affect of multiple processor
blocks in the signal path.
Frequency
This indicates the frequency of the selected filter. You can change the value
by clicking on the spin buttons, using keyboard controls, or by entering a
specific value. The frequency range is from 25Hz to 20kHz, with "OUT" as the default setting.
Figure 40 − DFR10 Window