may be of interest to some of you with respect to early electronic music (this goes back to the 1930s). may not count as 1-bit per se, but low level for sure!https://en.wikipedia.org/wiki/Variophone
And here's a clip of it in action. Love how visually pleasing it is as well : )
https://youtu.be/4r4WqAf-X8Y
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