KA-303 Acid Bassline Synthesizer

The sound that invented Acid House, Acid Techno and Hard Acid. Built for your DAW. No compromises, no hardware required.

The KA-303 takes the legendary 303 sound as its starting point but goes far beyond cloning. Circuit-modeled at component level, not emulated. With a full Composing Engine, four distortion models, a Unison Engine with up to 7 voices and the Angel Fish Mod as a standalone sound extension, the KA-303 is its own instrument with its own character.

Circuit-Modeled Diode Ladder Filter

A detailed reproduction of the original diode ladder circuit at component level with Zero Delay Feedback architecture. Four cascaded integrator stages with asymmetric coefficients, soft-clipping saturation modeled after 1S2473 silicon diodes, the original 150 Hz highpass in the feedback path. The fat, signal-dependent squelch that transistor ladder designs simply cannot replicate. Slide, Accent and the Gimmick Circuit are also modeled at component level, including the capacitor-based accent sweep that accumulates across consecutive accented notes. Just like the hardware.

Waveform Morph

Every other 303 plugin forces you to choose: Saw or Square. The KA-303 doesn't. A dedicated MORPH knob blends seamlessly between both waveforms. At 30% with high resonance you get timbres that neither Saw nor Square can reach alone. Fully automatable via MIDI CC.

Angel Fish Mod

Inspired by Robin Whittle's legendary Devil Fish mod. Overdrive, Muffler, Filter FM, extended envelopes, adjustable portamento. One click and the 303 gets an entirely new dimension. From warm overdrive to aggressive filter FM to screaming leads with Hi Reso.

4 Distortion Models with Intelligent Crossover Logic

DS-1, Tube, Rat, Fuzz. But the magic happens before the distortion: a Pre-Distortion Crossover splits sub-bass and mids. The bass stays clean, distortion only hits where it belongs. HP Resonance adds the characteristic nasal growl, ENV>HP couples velocity to the highpass frequency for dynamically responsive distortion. From light crunch to aggressive acid growl without the bass falling apart.

Composing Engine.

Built specifically for acid basslines. An intelligent note grid only allows notes within the selected scale. Wrong notes? Not possible. Slides and accents visible directly in the piano roll. 98 factory patterns from "Chicago Deep" to "Berlin Basement" to "Final Boss." Scramble, Mutate, Octave Jumps, Groove and Density as creative tools. MIDI Drag & Drop straight into your DAW. Dynamic Pattern Grid with lengths from 1 to 32 steps for polyrhythmic patterns. Page System for chaining multiple pages per pattern. MIDI Import. Groove Engine with five modes: Tight, Shuffle, Funk, Push, Laid Back. Grid resolution: 1/8, 1/16 or 1/32. Lasso selection for precise editing.

Unison Engine

Up to 7 full synthesizer voices, each with its own filter, envelopes and slide processor. Stepless detune and stereo spread. From subtle thickening to a massive wall of sound. Automatic gain compensation across all voice counts.

Built-in Effects

Tempo-synced stereo delay with crossfeed and darkening filter. Signalsmith reverb with room sizes from 0.3s to 5s. Brick-wall Master Limiter. Up to 8x oversampling. Full MIDI CC mapping via right-click and MIDI Learn. Dark and Light theme.

Formats: VST3, AU, Standalone Systems: macOS 10.14+, Windows 10+, Linux Price: €89 (Introductory: €69) Free demo available (all features, no time limit).

https://kreuzberg-audio.com/downloads/ka-303-acid-synthesizer/

Source: https://www.kvraudio.com/product/ka-303-by-kreuzberg-audio