Here are some more recent shots from Droneo - I have to come up with version info and instructions.
A Tone Spiral is a way to organize the intervals used in a Droneo voice so that you can see how they relate to each other and to various sets of intervals.
Every loop of the spiral is another octave, and octave related intervals are all on the same line. You touch and drag around the little circle , which represents a reed's interval, and you hear in real time what that reed is doing with that resultant pitch (and chorus and volume setting and churn). It's very interactive.
"off" reeds organize themselves in the center for easy differentiation. You can have your drags snap to the guide intervals (picked by the interval buttons), or retune intervals to the nearest guides for comparisons. When not snapping to the guides, the same button is used to randomly perturb the tones, like the "Rand" button does.
The button with the check in the corner means you will replace the original intervals with these new ones, otherwise the the button with the cross will revert to the original intervals.
Droneo 1.1 also adds the two insect timbres used by SrutiBox.