I particularly enjoyed the Cuckoo overview of FM principles that I came across in the Audulus forum thread on AM/FM/PM modulation.
I’ve since been wanting to take a closer look at the difference between linear and exponential frequency modulation and came across this video (also featuring an old ARP Oddysey Mk I) by Synthesizer Keith.
There’s a follow-up Reddit thread also clarifying that it’s linear modulation at play in the Yamaha DX style FM – the phase type of frequency modulation that Cuckoo refers to in his video – as well as a similar thread at KVR.
Keith refers to the Yamaha style linear FM as being “more musical” in his video, and there’s a Reddit thread, leading to a Muff Wiggler thread, on that question as well.
I found it interesting to look through the Wikipedia entry on Frequency modulation synthesis. I always associate FM with the 80s (the DX7!) but as the article points out Yamaha was already developing (and patenting) it (after famously licensing it from John Chowning1 ) in the mid 70s. It was only in 1980 that they’d developed the technology to a degree stable enough to release it commercially in the form of the curious Yamaha GS-1.
All of which was preceeded by Buchla with his own developments and implementations in the mid-60s.
Chowning patented the digital implementation of FM in 1975. ↩