interesting. so how are you playing diads? i guess you're using two synth voices, but how is one note being sent to one synth and the other note being sent to the other? (if you get my meaning...)
Yes, I'm using two of the three voices to play diads.
Key presses can control either the SHIFT or FREQ parameter of the selected voice(s), this is controlled by the Keyboard Mode Select switch.
At 0:43, the keyboard is in Mono mode, controlling SHIFT, all three voices are selected, tapping Middle C sets SHIFT=0 on all 3 voices.
At 0:46, the keyboard is in Mono mode, controlling FREQ, all three voices are selected, tapping Middle C sets FREQ=261.6Hz on all 3 voices.
At 0:53, the keyboard is in Mono mode, controlling SHIFT, with only Voice 3 is selected, I tap the low A note which sets SHIFT=-17
At 2:05, the keyboard is switched to Poly mode, controlling FREQ, with Voice 1 and 2 selected, then I play a few diads
At 3:18, the keyboard is switched to Mono mode, controlling FREQ, Voice 1 and 2 are still selected, and play in unison
I like to use Freq mode so I can bend notes using the FREQ controls on the iPad screen (starting at 4:42 in the video).
The voice allocator works on most recent note priority, and steals the oldest note held to play a new note. When there is a key-up event that frees a voice, the allocator looks for the lowest key held which is not sounding. I've designed the voice allocator to support up to 6 voices, so eventually I'll be able to play with 6 voice polyphony using both Synth blocks. But right now the Synth screen and the keyboard is controlling only one synth block at a time.