This mod source outputs a different value for each note played, based on the round robin voice number and the number of voices allowed.

The dropdown box below the voice mod section control how many voices are available - say 8 voices.

Each time you play a note, that note is assigned a number.

The first note would be voice 1 / 8.

The next note played would be 2 / 8 and so on.

This means you can have a mod source that outputs a different value each time you play a note, even if it's the same note over and over.

Output Curve

Clicking the small graph launches the output curve popover.

On this page, you can see the values of the round robin voice number and the mod output value.