Cross Modulated Microtonal Improvisation

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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

It Spoke to Me in a Strange and Rhythmic Language

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This dissonant microtrack was created on the Roland MKS-80 with MIDI mapping on a Korg nanoKONTROL for real time manipulation of the settings. I setup three scenes on the nano to control virtually every parameter, although I was only adjusting a few of them for this recording. What makes this patch so interesting to me are the opposing oscillator frequencies. I managed this by routing the LFO to the VCO and by using cross modulation, which are settings on the MKS-80 that I’m just starting to get familiar with. Everything else on this machine fits snuggly into the subtractive synthesis model, but the cross modulation uses the second oscillator to modulate the pitch of the first. This can be used to produce FM or frequency modulated sounds including bell like tones similar to what the famous Yamaha DX-7 was doing around the same time.

It Spoke to Me in a Strange and Rhythmic Language

Real Time MKS-80 Programming

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Now that I have the MKS-80 repaired I have started organizing ways to program the synth in real time. Without the MPG-80 programmer, or a suitable substitute, the MKS-80 does not lend itself well as a performance instrument. At least that is the case if you’re like me and insist on having real time tactile control of a good majority of the parameters. The following sequence was recorded while programming the MKS-80 in real time utilizing the reKon Audio VST-AU MKS-80 Editor mapped in Ableton Live to a MIDI controller. The MIDI controller I used only has about twelve assignable knobs and sliders, so I carefully chose the parameters that would provide the more interesting results. This included most of the parameters in the VCF plus LFO speed and cross modulation.

MKS80 Arp Real Time Control

Roland MKS-80 Super Jupiter Repair

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I recently purchased a Roland MKS-80 in need of repair. Several things were wrong with it including the tuning knob, dynamics slider and “insert cartridge” errors when trying to change the patches from the front panel. Without being able to tune the synth or utilize the dynamics, the instrument was effectively unusable, but I decided to buy it anyway in the hope that it could be repaired. After several days and more than thirty hours of research, parts swapping, and troubleshooting I managed to get it working properly. Read on for an illustrated story of the repair process and audio from the fixed unit.
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