Pre-process section, 3 pre-process section – Sonnox Oxford Limiter User Manual
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3 PRE-PROCESS SECTION
3 Pre-ProcessSection
The Pre-Process section
provides a musical programme levelling function.
Its primary purpose is to control programme
level over a wide range, in order to create
optimum conditions for the following enhancement
stage. When the
ENHANCE control is disabled in
Normal Mode (at 0% with
SAFE MODE deselected),
the Pre- Process section can be used as a
conventional levelling section in its own right.
For clarity of operation, the plug-in gain structure
is arranged with the threshold permanently set to
0dB, referenced to normal input level. Dynamic gain
reduction is achieved by increasing the
INPUT GAIN sufficiently for the internal signal to
surpass the 0dBr reference level. A total of 18dB gain boost is available for this purpose,
and the orange section of the
INPUT meter illustrates the level range within which gain
reduction occurs when the plug-in is active. The final output modulation level is set by the
OUTPUT LEVEL control, which can be adjusted to compensate for dynamic conditions
produced by the programme and Limiter settings, or produce a lower level mastered
output if required.
Programme gain is accurately controlled by look-ahead detection (to allow action before
any peaks are encountered) coupled with a logarithmic sidechain employing multiple
interdependent timing functions. Timing controls are provided to modify its action
depending on the programme type and production style. In order to reduce excessive
short-term gain modulation, a selectable
AUTO GAIN function is included, which
compensates for wider input level variations by imposing a longer-term time constant that
underlies the peak timing. A variable progressive
SOFT KNEE function allows varying
degrees of soft limiting (for lower settings), right up to large-scale gain management
active over the final 10dB of programme dynamic range.