[b3orn]

It's not how all synths work, probably the most famous FM synth the DX-7 never had a filter, additive synths don't really need filters either, but for a subtractive synth this would be unthinkable. And the general architecture of any synth is usually not that hard, you have a source, possibly filters, an amp and some modulators.

[weatherlight]

My friend, with the app above you can take 6 VCOs, have them modulate each other and understand how the FM(phase) synthesis on a DX7 works. Instead of guessing. Explore why certain ratios produce bell like tones etc.

One of may favorite digital synths is the TX-81z. 4op FM. One of the first digital synths where the operators weren’t restricted to sine waves. (DX7 had 6op FM)

If you just look at the specs. And even play with the values you won’t understand why one synth could obtain sounds the other couldn’t.

That “source” is usually the synthesis method.(usually the complicated part outside of anything that’s not a traditional VCO)

If you have a filter, the resonance imparts a particular sound as well.

Digitone is 4op fm as the source then that’s funneled through a pretty standard east coast architecture.