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4800/4820 User Manual
Type switch
The Type switch toggles the AFS function between different sensitivities and filter Q settings corresponding
to the type of application. The different Types are Speech (Highest Sensitivity, Bandwidth = 1/5 octave and
Q=7.25), Music Low (High Sensitivity, Bandwidth = 1/10 octave and Q=14.5), Music Medium (Medium
Sensitivity, Bandwidth = 1/20 octave and Q=29), and Music High (Lowest Sensitivity, Bandwidth = 1/80
octave and Q=116).
Detector Highpass fader
This parameter sets a Highpass filter in the path of the AFS detector. There may be occasions where the
AFS algorithm is removing too much low end because it is being triggered by Synthesizer or Bass notes that
are not really feedback. These waveforms can be tricky because the notes will not only appear to be feed-
back to the algorithm, they will also cause the filters to widen out because they appear like several feedback
frequencies closely located to each other. This Highpass parameter provides a mechanism to make the AFS
algorithm less sensitive to low frequencies (thereby setting fewer filters in the bass region) and is adjustable
between Off, 11.7 - 410.1Hz.
Sensitivity fader
The AFS algorithm is very effective when the audio has a nominal level of 0 dBu. However, if the audio is
too low in level the AFS algorithm may not catch feedback as quickly as possible. By increasing or decreas-
ing the sensitivity you can adjust for audio that is either too loud or too soft and help the AFS function
properly. The Sensitivity fader can be adjusted between up to +/- 20dB.
Live Filter Lift switch
This parameter turns the Live Filter Lift functionality on and off.
Lift After fader
In Live mode the AFS filters offer Live Filter Lift which can remove extraneous filters. This parameter sets
the timer length for the live filter lift. Once a filter’s timer has run out, the algorithm checks to see if the
filter is still necessary. This timer ranges from 5 seconds to 60 minutes.
Number Fixed fader
This parameter sets the number of Fixed AFS filters. This also sets the number of Live filters; the total
number of filters minus the number of Fixed Filters equals the number of Live Filters. The number of
Fixed filters can range between 0 and 12.
Total Filters fader
This parameter selects the total number of filters available and can range between 0 and 12.
Detailed Parameters
Section 6
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