This makes simple waveforms that follow a sequence of spectral change in steps. It sounds a little like the Korg wavestation or other wavesequence synths, but unlike those sample table based devices this uses an extremely simple synthesis method. Two modulo counters, x and y, operating over 1-32 steps are separated by a variable interval i, are combined with a random integer r, to form a small integer ratio 1+(x/i+y+r) which cycles up forever. These two numbers are used as the frequencies of two oscillators feeding a modulation stage such that the spectrum of the sound changes on each step. Since the maximum step size sets the highest number and the length of the sequence some interesting patterns emerge. For an example, if the ratio numerator is 3 and the denominator is 4 and the offset is 2 then the numerator will count 1, 2, 3, 1, 2, 3.... and the denominator will count 2, 3, 4, 5, 2, 3, 4, 5 .... therefore the first ratio in the sequence will be 1+1/2 = 1.5, the second will be 1+2/3 = 1.3333 and the third 1.75, fourth 1.2 and so on. The total sequence length will also be 12 in this case.
demo.
No interface. Feel free to disect the gubbins and build one. Parameters available in the programming list are (sequence offset int 0 - 16, ratio numerator int 0 - 30, ratio denominator int 0 - 30, random wander int 1 - 5, odd/even harmonic mix float 0 - 1, harmonic phasor mix float 0 - 1, clock period int 10 - 400, bar length int 0 - 8, note1, note2, note3 int 0 - 127)
Take the cosine of a small number plus the sum of two sine waves. The two oscillators, one for the fundamental and one for the harmonic are combined, added to a number between 0.25 and 0.5 and used as the index of the cosine function. A mixture of this signal and the original phasor of the harmonic is output.
The patch of interest is "Mozarts Ghost" which I find quite bizzare, but the other couple of patches show some variety of more subtle spectrum sequencing.