Spatial chorus effect with fractal modulation and enhanced user functions (revised version)

Abstract

The underlying strategy of the stereo chorus effect is to emulate the combination of multiple similar voices in unison and provide an extended stereo image. Like it’s close cousin the flanger, it also uses a system whereby a signal is added to a dynamically delayed exact replica of itself. One important distinguishing factor between the two effects however lie in the way the delay line duration is modulated. For a chorus effect to attempt to recreate the realism and tiny discrepancies of a multi-layered ensemble, the modulation must be generally faster, and provides a superior result if the modulation has a random character, rather than a regular periodic character. Chorus effects in general give the user little control over both the modulation signal and the spatial aspects inherent in chorusing. This paper will discuss a new design for a ‘spatial’ chorus effect that incorporates a modulation signal derived from a fractal algorithm with resonant low-pass filter control on the modulation signal. The implementation provides extensive user controls and parameters that center around the de-correlation of left/right signal paths resulting in a spatially enhanced outcome.