Here’s another result of experimenting with the Roland Juno-106. I created this sound by using the VCF as a pseudo oscillator. I cranked up the resonance to full, and put the cutoff at about half way, then turned off both the square and sawtooth DCOs. You might assume that with the oscillators off, including the noise and the the suboscillator, that the synth would make no sound, well it doesn’t really until you almost max out the resonance. Maxing out the keyboard slider changes the pitch of the notes on a roughly twelve tone scale, but it’s not well tempered, so this creates an eerie detuning between the notes. See the photo above for the exact settings. In the recording you’ll notice an abrupt key change happening a few times where I turned on the sawtooth oscillator. I also nudged the LFO on the VCF here and there to add to the spooky factor.
I’ve done a similar thing with the Pro One before, but it sounds really nice in six voice polyphony on the 106. My guess at what’s happening is that a sort of controlled resonant feedback on the instrument’s noise floor is creating the pitches. This is something that doesn’t really work with digital filters on modeling synths, as far as I know. I know that I haven’t been able to reproduce this behavior on the Korg MS2000. I don’t fully understand what’s happening, but that’s my theory. If anyone has better insight, please share a comment on the article.