Toxic

note:v1.0.2 Released.
— Improved realtime UI rendering performance with more targeted repaint paths.
— Added an OpenGL-backed realtime renderer path while keeping JUCE fallback drawing for compatibility.
— Fixed realtime display regressions where LFO, Envelope, FFT/filter views, assignment arcs, or assignment spots could appear frozen or blank during UI updates.
— Smoothed category and routing toggle animation, including the signal-flow refresh after Serial / Parallel changes.

Dual-Filter Motion Lab

Toxic is a free dual-filter effect built for the KVR Developer Challenge 2026. It combines serial/parallel routing, three drive stages, analog and digital filter models inspired by the topology of a hardware VA synthesizer, LFOs, an envelope follower, and macro control in one performance-ready plug-in.

Filter concept

Toxic's filter section is inspired by the topology of a legendary hardware VA synthesizer: a flexible dual-filter structure with serial/parallel routing, multiple analog-style and digital-style filter characters, and formant/vowel movement designed for animated sound design.

It is not a clone or an official emulation. The goal is to capture the workflow idea of a performance-oriented dual-filter synthesizer architecture and rebuild it as a free creative effect for modern DAW use.

Key Features

• Dual Filter Architecture — Filter 1 and Filter 2 can work in serial or parallel routing.
• Analog / Digital Filter Selection — Each filter can switch between analog-style and digital-style filter families.
• Multiple Filter Types — LPF, HPF, BPF, Notch, Peak, All-Pass, Comb, Buzz, Formant, and other character models.
• Three Drive Stages — Input Drive, mid-stage Drive 2, and Output Drive let you shape density before, between, and after the filters.
• Drive Character Choices — Tube saturation, diode clipping, germanium clipping, foldback, tape-style saturation, crunch, soft/hard clipping, bit crush, and decimation.
• LFO 1 / LFO 2 — Free-running or host-synced modulation with sine, triangle, saw, square, pulse, S&H, Perlin, stepped, damped, chirp, bounce, and ring-style motion.
• Envelope Follower — Drive the filter from the input signal with Attack, Hold, Decay, Release, Threshold, Scale, Amount, and Invert controls.
• Macro 1 / 2 / 3 — Assign multiple parameters to one performance control, including positive and negative modulation amounts.
• Expert / Perform UI — Use Expert mode for detailed patch design, then switch to Perform mode for large, direct controls on stage or during automation passes.
• Modulation Arc Display — Visual feedback around controls shows assignment amount and modulation movement.

{See video at top of page}