> > FM synthesis, as such, was not new. The Buchla synthesizer featured it in the 60's.

> But the critical feature of FM synthesis that made it usable as a musical element was linear FM. Early synthesizers (like, I presume Buchla's) sported "FM" but it was exponential due to volt/oct.

No; the first Buchla oscillator, the 158, did indeed have linear FM.

And that was intentional. Early Buchla synths didn't have much going on in the filter department, so instead he made the oscillators extra expressive.