Updated March 27, 2014
Knobs are used to enter numeric values in real time. To change a knob's value, tap the knob and drag away from it in the direction you want the knob to point. The value will vary arithmetically or logarithmically as the knob is turned, depending on the parameter it represents.
All knobs have an associated edit box which shows the value. Tapping this box displays a number pad that can be used to enter exact values.
Double-tapping a knob instantly sets the value to its default.