Manual
Table Of Contents
- Introduction
- The Oxford DeClicker
- The Oxford DeBuzzer
- The Oxford DeNoiser
- Preset Manager Toolbar
- Supported Platforms
- System Requirements
- Copyright and Acknowledgements
3.2 TrackingModes 3 THE OXFORD DEBUZZER
control. This is a plot of strength of a given nominal frequency in the input signal, and the
display extends over a wide range either side of the nominal frequency. With the nominal
set to 50Hz, any peak frequency between 45Hz and 55Hz will be displayed.
The second tool to help isolate the fundamental is the large FFT display. The FFT
displayed by default in this graph is no ordinary FFT of the input signal, but can
accumulate FFT data. It is designed to accentuate any frequency components that are
consistently present, and average out everything else. Any buzzes, hums, whines or
whistles that are consistently present tend to stand out in the plot.
A third method of isolating the nominal frequency is a tone generator. In the same way as
you can tune a guitar, as you home into the fundamental, the beat frequency between the
tone and the fundamental will become slower and slower the closer you get.
The FFT graph will automatically mark the three highest peaks found. You can click on
one of these peaks to directly set the nominal frequency to the exact frequency found in
the graph. You can also drag the marker in the graph, or use the rotary control. The small
red triangle on the frequency axis notifies the nominal, and it can be dragged to
re-position the frequency knob.
Once the nominal frequency is found and set, the removal section uses this frequency to
calculate the coefficients required for the comb filter to remove this frequency and its
harmonics from the input signal.
3.2 TrackingModes
By default the plug-in assumes Auto Mode. This means that the plug-in is continuously
hunting either side of the nominal frequency for a peak profile, and then steps the centre
of the profile closer to the peak. Once the lock strength rises to be above a certain level,
the plug-in automatically sets the nominal frequency to the frequency of the peak found.
In Auto mode, the filters follow the detected frequency, not the nominal frequency set by
the position of the knob. So if the hum is wandering in frequency, the detector will
follow.
If the nominal is set to within about 5Hz of a 50Hz or 60Hz hum frequency, the plug-in will
automatically move towards the correct frequency and set itself up to remove that
frequency. Once you hear the hum disappear, you can then click on Freeze to set the
nominal to this exact frequency and stop the detector from hunting.
For removing whines and whistles it is best to set Freeze Mode, and then use the FFT to
find the frequency of the whines. These show up as peaks on the plot, and then you can
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