Korg Opsix Owner's Manual page 53

RESO (Resonance)
Resonance emphasizes the frequencies around the cutoff frequency, as shown in the diagram below.
This will have no effect with a setting of 0.
At medium settings, the resonance will alter the timbre of the filter, making it sound more nasal, or
more extreme.
Low resonance value
For some filter types, oscillation may occur within the filter when RESO (Resonance) is set
Note:
to a high value. This may cause the oscillation to continue even after note-off. To avoid this
kind of oscillation, use V.Patch to control the resonance value using an EG, or use a filter on
the Operator Mode side.
EG2 (EG2 Int)
This sets the amount that the EG2 modulates the cutoff parameter.
CTRL (EG2 Ctrl Src)
Selects the modulation source that controls the EG2 Int. The source selected here is multiplied with
EG2 Int to determine the amount of cutoff modulation. (See "Control Source List", p.78)
53
High resonance value