Roland SH-1000 Oscillator Waveform

YouTube via rolandsh1000
"Just a short video showing the oscillator of the Roland SH-1000, their first synthesizer. This synth is interesting because it uses a common organ Top Octave 6-stage Divider chip (LM3216) to create the oscillator waveforms. These chips are fed by a high frequency clock and they generate all the pitches of a musical octave (ignore what I say in the video about the signal outputs being footages). These are then divided down for lower pitch generation and, to create various waveforms, the various divided-down signals are mixed via resistor and capacitor networks to shape various oscillator waves.

In this video, I focus on the sawtooth wave, since that's a simple waveform that is usually generated in an analog synth by repetitively charging then resetting a capacitor with a constant current, to make a very smooth continuous ramp. In the SH-1000, not only does the sawtooth waveform have "bumps" due to the mixed pulses/squarewaves, but the shape of the ramp is different at different footage settings.

Roland had experience with these chips in other contemporary devices: I have a Roland EP-30 that has (I think) 8 of these LM3216 chips. It also tries to synthesize saw-like waves, but the resolution for the saw waveforms that keyboard is much worse. So, basically, if my SH-1000's TOD chip goes bad, I have quite a few replacements at the ready! ;)"