Troubleshooting guide

Modular Processors
SHURE
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P4800 System Processor Software Guide Page 59 of 108
Filter Allocation
The DFR uses two methods of filter allocation, as described below.
§ Fixed – You can manually specify these notch positions or designate them as fixed after the
DFR has automatically deployed a dynamic filter. They remain stationary regardless of newly
detected feedback frequencies. However, if the DFR detects additional feedback at that
position, a dynamic filter will deploy to increase the notch depth.
§ Dynamic – The notch position and depth are completely automatic. A dynamic notch will
deepen in response to increased feedback, and as new feedback frequencies are detected,
the DFR re-deploys the dynamic filters from oldest to newest.
The DFR allows you to select how many of the total number of notch filters will remain fixed, and how
many will be dynamically allocated as feedback is detected. Use a greater number of fixed filters on
input channels for stationary microphones. In this instance, the room acoustics define the dominant
feedback frequencies, which do not change appreciably. Use a greater number of the dynamic filters
on input channels for wireless or hand-held microphones. In this situation, feedback frequencies
change drastically as the microphone user wanders the room or sound stage.
You can designate the number of fixed versus dynamic
filters using either of the two techniques explained below:
To use the Fixed/Dynamic Filter Options dialog:
1. Select [Options>Fixed filters allocation] from the DFR
window's menu.
2. The Fixed/Dynamic Filter Options dialog appears,
as pictured to the right in figure 41.
3. Type the number of fixed filters you wish to allocate.
The number of dynamic filters adjusts accordingly.
4. Click [OK].
To change filter allocation with the mouse:
1. Position the cursor between the red brackets as indicated
to the right in figure 42.
2. The cursor changes to the horizontal resize symbol:
3. Click and drag left to increase the number of dynamic filters,
or right to increase the number of fixed filters.
High Q Filters vs. Low Q Filters
The DFR offers two width options for notch filters, as pictured
below in figure 43. High Q filters remain narrow as filter depth
increases, attenuating the minimum amount of signal. This
maintains high sound quality appropriate for most
applications, including music.
With the low Q setting, the filter notch maintains its shape
as it deepens, resulting in a wider range of frequency
attenuation. This setting creates greater system stability,
but with slightly diminished sound quality. This setting is
appropriate for speech-only applications.
§ To change the setting for an existing filter, click to
select the filter and use the [Type]
pull-down menu.
§ Use the [Options] menu to select the high or low
Q setting for all new dynamic filters as they are deployed.
Figure 41 − Fixed/Dynamic Filter Options
Figure 42 − Changing Filter
Allocations with the Mouse
Figure 43 − Notch Width Options