Freeware Mac/Win VST plug-ins Rebuilder and MixedGrains from Plogue Productions (www.plogue.com) are as whimsical and unique as they are easy to use. In fact, MixedGrains has no controls at all.
According to authors Alexis Bellavance and Gregoire Gerardin, Rebuilder is “mostly a DSP [digital signal processing] experiment that went berserk.” Rebuilder performs a fast Fourier transform (FFT) analysis on an audio file and attempts to resynthesize the sound using a large bank of oscillators. Theoretically, you can accurately reproduce the original source material in this way, which would, of course, be pointless. In reality the results range from a mildly distorted reproduction to total chaos, depending on the settings you choose.
Rebuilder's controls include Oscillator Waveform (sine, triangle, sawtooth, square, and ?), Pitch, Threshold (audio below the threshold is thrown away), and Processing. Processing controls the number of oscillators used; a higher number requires more CPU power. You can also control the size and shape of the FFT window.
Rebuilder is useful on voice and percussion. With voice you get interesting vocoder-like effects, and with percussion the resynthesis maintains the groove — the Threshold control is helpful here — while completely revoicing the drum kit.
MixedGrains randomly toggles between the two channels of a stereo input file. It does that by granulizing both channels; according to the authors, it selects the grains in a way that “has something to do with genetic algorithms.” Be that as it may, MixedGrains is lot of fun for processing stereo files with different material on each channel, for example. The big red slider in the middle has a fine resolution but appears to have absolutely no effect.
Rebuilder and MixedGrains work nicely together when MixedGrains is placed first in the signal path. You won't use these plug-ins every day, but if you're looking for something to jog your imagination, the Plogue Productions Web site is definitely worth a visit.