By the way, this
is similar to what Wilson says in his VCO writeup, and it infuriates me. It may all be true but it’s absolutely useless unless you know what to listen for. I don’t know how to identify “minimal harmonics” by the sound. In fact while adjusting the sine on my VCO, I found the apparent tone quality varied if I turned my head relative to the speaker. In the end I settled for something fairly sine-ish looking on the scope.