This is a demonstration of the new Macbeth Studio Systems X-Series Dual Oscillator – a high-end modular VCO.

via Bruce73X:

Demonstrating the Macbeth Dual Oscillator:

Pure oscillator sound going through a Analogue Systems VCA (RS-180), a Mackie Mixer and directly into the audio card (M-Audio) of the computer. No FX, no EQing.

First pure waveform listening and watching (sin and saw), than a little bit modulation (used the Sherman FB LFO for that) and at the end switching through the octaves with displaying the tune.