Get this Doc as PDFThe controls of Vocoder A, B, C, D are identical, but they vary in the band frequencies, which gives each a unique sound. Which of those will bring the best results depends on the used Modulator and Carrier signal.
Parameter 1: Gain Band 1+2 (0..100)
Parameter 2: Gain Band 3+4 (0..100)
Parameter 3: Gain Band 5+6 (0..100)
Parameter 4: Gain Band 7+8 (0..100)
Input 1: Modulator (Voice) signal Input 2: Carrier (Synth) signal
If you don't send a Carrier (Synth) signal to input 2 of a Vocoder, then an internal Carrier is generated (static at note C2).
Please keep in mind, that a Vocoder is in fact much more than a simple effect. An 8-Band Vocoder uses around 20 times more CPU than a regular Band-Pass Filter and around 30 times more than a Delay Effect.