Haunting resonance from my Korg Poly 800 with HAWK800 upgrade.  This is all realtime tweaking done using the NRPN control feature in the HAWK OS upgrade.
Raw Poly sound is ran thru Chorus, Delay and Flanger.

This is perhaps my favorite trick that the HAWK mod can do with the Poly..  All you really hear is one held note while I modify LFO1 rate, depth and the Square wave LFO modulation PWM phase from a short dash to a full dash/width.
You can barely hear any Oscillator sound, it's almost pure resonance!  That and some killer modulations! 

KillerKorg

Synthetech