SoundRave ATROPA: Free VA Synth with 4 Layers and Dual Filters

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SoundRave has released ATROPA, a free virtual analog synthesizer for macOS and Windows. The instrument is built around a subtractive synthesis workflow and aims to keep deep sound design accessible without hiding features behind endless menus.

Four-Layer Architecture

ATROPA offers four independent synthesis layers, each equipped with two main oscillators plus a sub oscillator and a noise generator. The oscillator section covers MultiSaw, pulse width control, oscillator sync, as well as FM and AM. In addition, the synth supports WAV-based sample and wavetable playback.

Each layer includes dual filters with 64 filter types, which can be routed in serial or parallel. Filter features include cutoff sync, topology-aware slopes, digital special models, and cascade drive.

Modulation and Workflow

Modulation is handled by envelopes, LFOs, a step modulator, six macro controls, an XY controller, and a 16-slot modulation matrix with drag-to-route assignments. The instrument supports up to 32 voices.

For workflow, ATROPA includes a unified preset browser with factory and user libraries, search, categories, favorites, and import/export. Moreover, an A/B comparison function lets you switch between two sound states, and a randomizer works on selected layers or globally.

Modular Effects

The integrated effects section is modular. Therefore, you can add, reorder, bypass, or remove processors as needed. At launch, 16 effects are included, such as drive, delay, reverb, chorus, phaser, flanger, EQ, filter, compressor, limiter, gate, ring modulator, and stereo imager. The standalone ATROPA FX app shares this chain and can also be used on its own.

Optional premium effects can be purchased separately, while the core instrument remains free.

Availability

ATROPA is available as a free download for Windows 10 or later and macOS 10.13 or later, including native Apple Silicon support. It runs as an AU or VST3 plugin, and a standalone manual is provided. Downloads require an email newsletter signup.

Pros

  • Four independent synthesis layers with dual filters and 64 filter types
  • Comprehensive modulation options including matrix, step modulator, macros, and XY controller
  • Free core instrument with modular, editable effects chain

Cons

  • Premium effects require separate paid purchases
  • Download requires newsletter signup; preset installation can overwrite same-named files

More info: SoundRave | ATROPA