Tokøta, from Mastering.com's Logic Pro course, walks through EVOC 20, Logic's polyphonic vocoder built for vintage, retro-style textures rather than modern robotic vocals.
The key setup step: EVOC 20 needs a sidechain input, here an acappella, to analyze the vocal, plus MIDI chords played into the synth to actually generate sound. Without both, nothing triggers.
Once it's running, the shaping happens through polyphony and voicing, attack and release for both the synth and the sidechain analysis, and band count, where fewer bands smear the vocal into something dreamier and more bands pull out sharper detail.
Further character comes from formant shifting and stretching, resonance boosts, LFO modulation, blue and white noise coloring, and dual ensemble modulators for width and thickness. Built-in presets like Smoke and Blow Up Dreams show how far the tone can be pushed.