FM was always possible with analog, but it sounded like a mess because you need digital stability to make consistent sounds. Tiny frequency variations that add

FM was always possible with analog, but it sounded like a mess because you need digital stability to make consistent sounds. Tiny frequency variations that add drift to analog sounds and make them interesting will completely destroy an analog FM patch and turn into unplayable noise. If you really want to explore FM you can write your own code and create algorithms with as many carriers/oscillators as you like. This turns out to be less interesting than it might be, although if you use a lot of carrier/modulator pairs you get a kind of spicy variation on additive. It gets much more interesting when you add formants and other variations like the later FS1R synth did. If you want to keep the modular approach the various digital modulars - Reaktor, VCV Rack, Voltage Modular, etc - give you clean FM with patch cords.