Full Bucket FB3 is a free plugin emulation of the Kawai K3, the hybrid synth from 1986 that ran digital single-cycle oscillators through a genuine analog resonant filter. FB3 rebuilds that voice, keeps the K3's drawable additive user waveform, and removes the hardware's practical limits.
What you are actually getting
The K3's appeal was its hybrid signal path: crisp digital oscillators softened and dirtied by an analog filter. FB3 recreates that path, including the single custom waveform you build by setting harmonic levels. It then raises polyphony to 64 voices, adds MTS-ESP micro-tuning and MIDI Learn, and reads real Kawai K3 SysEx patches so decades of existing sounds load directly.
The honest limitation
The original K3 filter was simple, and FB3 stays faithful to that rather than modernizing it. There is one additive user wave per patch and no onboard effects rack. This is a period-accurate recreation, not a modern do-everything synth, and that focus is the point.
Verdict
FB3 puts a faithful, free Kawai K3 in your DAW, with the additive wave and raw filter that made the hardware worth remembering, plus modern polyphony and patch compatibility. Read the full Full Bucket FB3 review for the feature-by-feature breakdown and the hardware comparison.