Sonnox Oxford Restore - Manual (Page 27)

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The 17 handles are distributed over the entire frequency range. With the display set to linear
view (HF view), 10 handles are visible from 2kHz to 20kHz. When the view is set to Log (LF), 9
handles are visible from 20Hz to 4kHz. Two of the handles (at 2kHz and 4kHz) are visible in
both Linear and Log views, hence there are 17 separate handles in total. The shape of the profile
as modified by the bias handles is preserved while switching between views. The Reset Bias
button is half-bright when any handle is not at its null position. Clicking the Reset Bias button
will reset only the handles that are visible in the current log or linear view. Holding down shift
while clicking the Reset Bias button will reset all 17 handles in both views.
These threshold bias handles are useful when trying to de-noise band-limited signals. The
contour of the threshold profile is likely to drop rapidly at the bandwidth limit, and it is possible
that noise elements will peek over the threshold. This behaviour could result in the introduction
of musical noise. Raising the threshold bias handle just to the HF side of the bandwidth limit will
rectify this and reduce the musical noise.
There are some shortcuts for adjusting the bias curve on the graph:
Left Click + Drag: adjusts a single bias handle.
Right Click + Drag: adjusts that handle and all others above it to the end of the HF. This
allows a very quick way to add gentle de-hissing – right click at 8kHz and drag up.
Shift + Left Click + Drag: adjusts that handle and all handles below it down to start of
LF.
5.3
Noise Reduction Bias Controls
For additional manual control over the noise reduction, there is a 17-step noise reduction bias
curve that is very similar in operation to the threshold bias. This curve is coloured yellow. The
adjustment of the noise reduction works in all three modes – Auto, Freeze or Manual. Using
this reduction bias curve you can easily reduce the amount of noise reduction at particularly
critical frequencies, for example where piano transients are brightest and most obvious. This
ability to tailor the noise reduction allows for a much more musical result that shows good noise
reduction while also being sympathetic to the character and ambience of the original.
The Bias Select toggle button is used to switch between the Threshold Bias and the Reduction
Bias. The control of the reduction bias handles is identical to the control of the threshold handles,
which is described above. The Reset Bias button glows to show that one or more handles on the