On the SP-404MK2, the vocoder pitch is controlled by transmitting note messages from an external MIDI device, not by the audio input. The audio input (mic, instrument, etc.) is used as the carrier signal.
To control the pitch, transmit note messages (note numbers 0–127) from one of the following:
- Set the pitch using the "NOTE" parameter in the vocoder effect settings. Value: -17– -1, 1–18
- Transmit note messages (note numbers 0–127) from a MIDI keyboard connected to the MIDI IN connector, a computer connected via USB, or DAW software on an iOS device.
Set the MIDI channel on your external device to channel 11. To change the pitch continuously, transmit pitch bend messages.
For details, refer to "Configuring the input effects (INPUT FX)" and "Vocoder" in the SP-404MK2 Reference Manual.