One vey cool capability in Volcano is that stereo filters have a Pan control. What this does is to reduce the cutoff in the direction being panned toward, and to correspondingly raise cutoff in the other channel. There are numerous presets in Volcano that use this to great effect (no pun intended).
But the panning effect on filter cutoff is a secondary "seasoning" - something you'd throw on (modulation of panning, that is) after setting the initial cutoff and maybe modulating that with a XLFO. It was this I was trying to accomplish with MXXX and could find no way to do it - not even by playing games with esoteric chains of modulators controlling range settings of other modulators. Maybe there is a way to do it and I just haven't been smart enough to figure it out - sadly, that has been known to happen.

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