It's a nice article, but I think there are some important things to note here:<p>Typically, what we call "FM synthesis" is implemented as phase modulation -- instead of modulating the frequency of the carrier, you modulate a phase offset. That way, the amplitude of the modulator won't have to be scaled with the frequency of the carrier for a uniform timbre over the whole frequency.<p>My second note is that most FM synthesizers (the whole Yamaha range, basically) don't define the frequency ratio increments in octaves or quarter octaves, but simply as multiples of the base frequency, producing a harmonic series. Most implementations do this in integer increments, but others like the DX7 and TX81z let you use fractional frequency multiples.
For what it is worth, I have made a similar work with much less details and very poorly designed, but here are some cool FM instruments: <a href="https://github.com/tfjgeorge/jsfm#gong" rel="nofollow">https://github.com/tfjgeorge/jsfm#gong</a><p>To hear the sound click the speaker on the right (works at least with Chrome).