I was the same! I saw synthesizers in the mid-70's and heard some Wendy Carlos tunes and Rich Wakeman and said "Now THAT is a pretty cool instrument!" That lead

I was the same! I saw synthesizers in the mid-70's and heard some Wendy Carlos tunes and Rich Wakeman and said "Now THAT is a pretty cool instrument!" That lead to me taking an electronic music class in college to get access to a Moog Model 15, and then to buy Hal Chamberin's book Digital Music Synthesis, and eventually to buy a synth from Roger Arrick who runs synthesizers.com and basically hand builds modular analog synths. Designing those "fat" analog sounds from the 70's requires a subtractive synth which starts with a harmonic rich waveform (like a sawtooth) and then applies filters to it that are modulated by an ADSR envelope. Dr. Chowning over at Stanford invented (or at least documented) using FM modulation (mixing) of multiple sinusoids to achieve interesting sounds. That was the basis for the Yamaha DX-7 and you can hear it on a lot of 80's and 90's band tracks. His book is somewhat dry but it goes over the theory well and with something like the Yamaha TX81z sound module you can put his ideas into action and hear the results. Later synthesizers went full on DSP which allows you to effectively emulate that other forms and also to do things that they can not (like phase coherent modulation schemes). All said, for me at least, playing with the model 15 in college and playing with my Arrick 22-slot modular synth since, has been the only way for me to internalize the connection between the sound I wanted to hear in my head with how to set things up to produce it.