Cross Modulated Microtonal Improvisation

I created this plucky microtonal patch by using the cross modulation on the Roland MKS-80 to effectively put the instrument into an instable, out-of-tune state. I mentioned in my previous entry that cross modulation is a form of frequency modulation or FM synthesis made famous by the Yamaha DX-7. My curiosity about this technique led me to an article in Sound on Sound from 1994 titled Exploring Analogue (Part 2) by Steve Howell. In the article Howell states,

“…take the output of one oscillator (Osc A) and feed it into the control input of another (Osc B). As the modulation level at Osc B’s input is increased, so its tonal quality becomes progressively nastier. In fact, in the absence of a ring modulator, cross-modulation can be used very effectively to create clangorous bell sounds and the like. But be warned! Because the tuning stability on old analogue synths leaves much to be desired, the oscillators don’t track too well, and a sound that is perfectly tuned on C3 may well have disintegrated by the time you get up to F3.”

On the Roland MKS-80 the tuning stability is pretty good, but it does use VCOs (voltage controlled oscillators), so they won’t track as well as DCOs (digitally controlled oscillators). This imperfection is part of what many of us find attractive about analogue synthesis, and what made it possible for me to produce this bizarre, out of key, yet delightful sound.

Cross Modulated Microtonal Improvisation

5 thoughts on “Cross Modulated Microtonal Improvisation

  1. Pingback: Audio Cookbook » Blog Archive » Clangorous Cross Modulated Analogue Bells

  2. Beautiful sounds and tuning scheme! The upper register is particularly nice. I’m not sure how easy it would be to put together a polyphonic texture, but I’m curious to hear what thick chords would sound like.

    The intermingling of tuning and timbre you mention reminds me an interesting book by Bill Sethares called “Tuning, Timbre, Spectrum, Scale,” which discusses, surprisingly enough, the relations between those four musical properties. Sethares describes how timbres can be designed to optimally fit a microtonal scale and vice versa.

  3. @patrick Thanks! This is actually a polyphonic patch, I was just playing single notes, so harmony is something I might explore. Unfortunately I don’t have very predictable control over the tuning of the scale. I would love to experiment with more tuning schemes, but this technique doesn’t allow for specific programming of the intervals. I’d love to know if there is a way to do this. It it were CV versus MIDI it’d be possible. Yet another path to investigate! ;)

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