Thanks to the author for this. My amateur-hour electronics dream is to level up from simple Arduino/control voltage hacking to an actual, workable polyphonic synthesizer.
Going from simple dc arduino inputs to high precision analog is a bear, but super rewarding. Get ready to get your soldering skills right and start caring about resistor tolerances!
Another of my synth DIY mentors (with whom I worked on the Arturia MiniBrute) is Yves Usson: http://yusynth.net/index_en.php
Well thanks. There goes all my free time... But seriously, that website looks like an amazing resource