Wavefold uses a rectifier circuit that mirrors the negative half of the audio waveform to positive, doubling the fundamental frequency and introducing new harmonics. This is aggressive and harmonically dense. Otto Tron Direction Down creates an inverse dynamic — harder playing pushes the filter toward the low end while the Wavefold is opening up harmonics above. An Envelope on Wavefold Shape intensifies the rectification on hard attacks and then settles, so notes start more aggressively than they sustain.