LinPlug Alpha - Manual (Page 12)

100% (i.e. the dial is turned completely clockwise) it takes full 10 seconds.
The “fade” (Fade Time) dial is used to set the rate at which the filters cutoff frequency moves
from the Sustain value to either the cutoff parameters value (when the dial is turned counter-
clockwise) or maximum envelope depth (when the dial is turned clockwise). A middle Fade
setting (dial is set to 12 o'clock position) means that the filters cutoff frequency remains at the
Sustain level until the note is released.
The “depth” dial is used to set the degree to which the filter's envelope effects the signal.
Setting “depth” to -100% (i.e. turning the dial completely counter-clockwise) means that the
envelope has full negative effect on the filter. Adjusting the dial to the middle position means
that it has no effect on the filter. Setting “depth” to 100% (i.e. turning the dial completely
clockwise) means that the filter is modulated by the envelope's full range.
The negative envelope depth can be used for opening the Filter when a note is released
(which would be impossible with a non-inverted ADSR envelope).
LinPlug Alpha 3.3 Series User Manual Page 12
Filter Keyboard Tracking
Alpha has no dedicated control in the filter section to adjust filter keyboard
tracking. You can however, achieve this using the Matrix:
Note 0.4000 Filter Cutoff
gives a pretty exact tracking, so that the filter opens just like the notes go up.
For example from two notes played one octave apart the filter on the higher
note will be one octave more open (Cutoff is twice the frequency of the lower
note).
The tracking is pretty good for the usually keyboard range of 4 or 5 octaves,
and while it actually covers 10 octaves, its up to 4 semitones inaccurate at the
outmost ends of the spectrum.
On some old hardware you also found half-tracking which would translate in a
matrix depth of 0.2 while no tracking obviously requires no entry in the matrix.
Moreover negative tracking is possible this way as well, just use a negative
modulation depth here (the Filter than closes more and more the higher the
played notes are).