Official, state sponsored documanvideotorial by Industrial Music Electronics.
I think Walker Texas Ranger Farrell lent some dubs over it.
"The Hertz Donut is a complex digital oscillator with unison detune, programmable 3x4 modulation matrix mixer and external input. Intricate arrangements of phase distortion, thru-zero frequency modulation, and complex oscillation are instantly morphable and recallable through a voltage-controlled preset manager. Suitable for genre-targeted sequenced basslines, synthesis of stone, glass, and steel tones, and simulation of the acoustic properties of industrial machinery." br> br>