FB3

Name: FB3
Author: Full Bucket Music

by Full Bucket Music · Synth · Kawai K3 emulation

Not rated yet

FB3 is a free emulation of the 1986 Kawai K3/K3m hybrid synthesizer, with its wave generator, filters, factory sounds and user-wave import.

It runs up to 64 voices and supports SysEx import/export, MIDI Learn and MTS-ESP micro-tuning; it is free.

Best for: Keys & Synths, Sound Design. Genres: Electronic & EDM, Pop, Lo-Fi.

Keywords: 80s, free, hardware emulation, polyphonic, additive, analog, CPU-light, monophonic, thin, basses, BBD, brass, digital classic, heavy, hybrid, leads, lo-fi, modern, organ, pads, resizable UI, sound design, strings, subtractive, tempo-synced.

What it does

FB3 recreates the Kawai K3 and K3m, a 1986 "digital wave memory" synth that ran digital waveforms through analog-style filters. The developer jokes that it "sounds nothing like the hardware", but it copies the K3's layout and patch format and adds several modern extras.

Two oscillators: each plays one of 31 ROM waveforms (from piano, strings and brass to square, saw and sine), a user wave or white noise, at 16', 8' or 4'; OSC 2 tunes ±24 semitones and ±30 cents.
User waves: build waves by additive synthesis from up to 32 harmonics, or import a mono WAV; each program stores its own internal and cartridge wave.
Filter and amp: a resonant low-pass VCF with its own ADSR and a low-cut filter, plus an amp ADSR; FB3 adds ENV INV, VCF OFFSET and a LOW BOOST control (-18 to +6 dB) to tame the K3's heavy low end.
LFO: seven shapes including random and semitone-quantised random, routed to pitch, cutoff and level, with an added host tempo sync.
Chorus: eight modes built on three bucket-brigade lines, some acting as short delays, plus a stereo mode.
Voices: 1, 6, 12, 32 or 64 voices (the hardware had 6), a six-voice unison Mono mode with detune, and portamento.
Patches and MIDI: 100 programs (50 internal, 50 cartridge), the factory sounds plus extra patches by Eric Väpnargård, K3/K3m SysEx import and export, MIDI Learn and MTS-ESP micro-tuning.

The current version is 1.1.1 (2 October 2026). The UI is resizable. It is a free download; the developer accepts donations.

Source: Full Bucket Music product page

When to use it

FB3 is the free way to get the thin, glassy digital-wave sound of a mid-80s Kawai, along with its factory patches and SysEx format. Compared with CS-80 V or Diva, it is a much narrower instrument with a simpler two-oscillator engine, but it covers a period colour those analog-style synths do not aim for. Unlike Serum 2 or Vital, it has no wavetable morphing or deep modulation matrix; its user waves are fixed harmonic spectra, closer to an early additive editor. It is also light on CPU, so it is easy to stack several instances.

Best for: 1980s digital pads, bells, organs and thin leads, chorused basses, and K3 owners who want their SysEx patches in the DAW.
Genres: synth-pop, synthwave, electronic, lo-fi and retro game-style music.
Look elsewhere if: you want a modern, flexible synth (Vital or Serum 2) or warm analog tone (Diva).

What producers say

The plugin is new, and early feedback on KVR is enthusiastic.

KVR users rate it 5 out of 5 from 1 review (September 2026, version 1.0), praising the "great user interface", the sounds, custom waveform loading, 64 voices, low CPU use, SysEx support and the "perfect expansions" such as voice count, chorus and VCF tweaks.
KVR comments: one user called it "Astonishing work."

KVR user reviews

Where to buy

Full Bucket Music: Free

Tutorials and reviews

Similar plugins

FB-7999 by Full Bucket Music · KORG DW-6000/DW-8000 emulation · Free
Ensoniq ESQ-1 by Cherry Audio · Hybrid digital/analog polysynth · $69
RetroMod Digital by Tracktion · Sample-based 80s digital synth · $79
D-50 by Roland · D-50 LA synth emulation · $149
Fury-800 by Full Bucket Music · KORG Poly-800 emulation · Free
Bucket ONE by Full Bucket Music · Crumar BIT 01/99 emulation · Free
ReDominator by AudioRealism · Alpha Juno polysynth emulation · $62.45
Six-Traq by Full Bucket Music · Sequential Six-Trak emulation · Free

All synths

FB3