Talking Bass Patch (Formant / Vowel / Vocal effect) by Otto van Zanten
Modulating the filter at audiorates to create a formant/vowel/vocal effect. Kind of sounds like a Daft Punk ish robot sound. Works well on pretty low notes, so for bass lines or octave-bass sequences for instance.
If it sounds a bit rough the resonance or filter cutoff might be too high. If it's played too low it sounds pretty rough too. Resonance, cutoff and osc3 speed can be varied for different vowel sounds.
I love to modulate the filter cutoff with a Sample and Hold from a different synth (like a Crave, Mother32 or Neutron) so every note gets a different sound and it almost sounds like different vowels or syllables. Almost, with a little bit of imagination. It can also sound like a weird broken robot voice if you vary it too much.