Korg PS 3200 - 3. Dynamic Low -Pass Filters (DLPF)

The Cutoff (Fc) & Peak are pretty standard.
The Peak emphasises resonance at the cut-off point.

The KBD filter balance:
This adjusts the Fc of each of the keys independent LP filters over a rising or falling slope corresponding to the scale of the keyboard.

Expand:
This adjusts the degree to which the EM  (envelope modifier) envelope signal affects the Fc.
The EM section is on the right of the filter. ... a standard ADSR.

MG1 or S/H modulation intensity
Like the one to the right which effects the SGs, this adjusts the depth of modulation from
MG1 & the S/h.