Clock-syncable oscillator detuning (beating)

[Tim Kleinert]

As the title says, this little building block provides the functionality of synchronizing the beat frequency between two oscillators to the G2 master clock (or an incoming external MIDI clock source).

Detuning two oscillators can potentially create quite pronounced sonic movement, especially when consecutive nonlinearities are involved. And as the ability to synchronize pretty much everything to the musical time frame (LFO and envelope rates, delay times etc.) is standard these days, its strange to see the probably most basic common sound-design technique (oscillator detuning) left out. I researched a bit and couldn't find any reference to this having been implemented anywhere -so this appears to be an industry first.

The circuit is based on the insight that the internal phase accumulators of G2 oscillators and LFOs share compatible numerical architectures. It derives the instantaneous phase increment from a clock-synced sawtooth LFO via differentiation (ignoring the wrap-around) and simply applies this to the linear FM input of the oscillator to be detuned against another one (both sharing identical pitch settings otherwise). With the circuit and both oscillators synced to the "clock active" flag, the oscillators will beat against each other in sync with the master clock at the relative rate set by the LFO. (Of course, if you tweak the LFO rate on the fly, you will have to restart the master clock if you want the phase angle of the oscillator beating to line up exactly with the clock downbeats.)

Polyphonic (key-synced) behavior could easily achieved by patching the gate signal from a 'keyboard' module into the oscillator sync inputs instead of the "clock active" flag. With a 2-1 switch, both functionalities could be implemented.

cheers,
-t

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ClkSyncOscBeatTK.pch2
Description:	synchronizes the beat frequency between two oscillators to the master clock	Download (listen)
Filename:	ClkSyncOscBeatTK.pch2
Filesize:	1.91 KB
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[Wan]

Thnx Tim, nice to see you still are very creative with the G2 platform:)