a spectrum is a picture. paint one. narrow strokes sing, wide strokes swarm into a cluster, and the width of the brush is the whole difference between a note and a cluster. then play the painting from a keyboard: every key slides the whole picture so the marked fundamental lands on that pitch.
the strip is the computer keyboard: press the letter on a key, or tap it · tab swaps layouts (cubase: white keys q to ], black on the number row · tracker: z-row and q-row, two octaves) · arrows: left and right shift the octave, up and down set velocity ·
the same brush width is 50¢ per sine everywhere, but 50¢ is 1.6 Hz at the bottom and 200 Hz at the top. so a wide stroke beats slowly in the bass and buzzes in the treble. the grid is 24 sines per octave, so presets snap to it: the 7th harmonic falls between two sines, 19¢ flat and 31¢ sharp.