Sound Radix has released Radical1 Solo, a free monophonic additive synth plugin for macOS and Windows.
I have not heard much from Sound Radix about new products in a while, but that is on me, since the company introduced Radical1, its first instrument plugin, in late 2025. The original Radical1 entered early access on macOS in December 2025, with Windows support arriving in early 2026.
I have fond memories of Sound Radix because their team was among the first people I interviewed for BPB during my first trade show visit, if I remember correctly, around Musicmesse 2015. Back then, they were showing 32 Lives, the 32-bit to 64-bit plugin adapter that helped old Audio Units and VST plugins survive in newer 64-bit DAWs.
Radical1 Solo is a very different product, of course, and it is also brand new. The Sound Radix release notes list version 0.9.6 dated August 4th, 2026, making this the first public pre-release of Solo.
The important part is that Radical1 Solo is not a time-limited demo. Sound Radix describes it as a free monophonic additive synth built on the complete Radical1 synthesis engine, with the same oscillators, modulation system, filters, and effects as the paid version.
The main limitation is that Solo is a single-voice, single-layer instrument, so it is best suited to basses, leads, and sequences. The full Radical1 opens things up for polyphony, layered sounds, expressive chords, and evolving textures.
What’s cool, though, is that sounds created in Solo remain compatible if you later move to the paid version.
Radical1 is based on additive synthesis, which means it’s generating sound from harmonic components that can be shaped, animated, and transformed. The engine includes Morphing Fluid Oscillators, Direct Spectrum Drawing, Spectral Sample Resynthesis, spectral shaping tools, harmonic modifiers, and a real-time spectral display.
I liked the workflow while testing it in Studio One. Sound Radix calls it a “What You See Is What You Hear” approach, with layers, modules, blocks, and modulation paths displayed as they affect the sound. Starred parameters keep important controls near the surface, while deeper sound-design tools stay available underneath.
The paid Radical1 is currently in Early Access, priced at $129 instead of the planned $199 full price, with a free trial available. It adds the full polyphonic and modular side of the instrument, including unlimited layers and modulation sources within CPU limits, Formula Blocks for custom DSP code, built-in MIDI effects, time-domain audio effects, and spectral block effects.
The latest 0.9.6 update also improves the Blocks and Samples Browser, adds a Route modulator, adds a Quantize modulator effect, improves distortion, adds MIDI settings for MPE routing and pitch bend range, and brings new and revised factory presets.
Radical1 Solo is available in AAX, AU, and VST3 formats for macOS and Windows. It requires macOS 10.14 or higher on Apple Silicon or 64-bit Intel Macs, or Windows 10 or higher on a 64-bit Intel/AMD system, plus 8GB RAM, a free iLok account, and iLok License Manager (USB iLok not required).
You need to sign up for a free Sound Radix user account to download the Solo version.
Download: Radical1 Solo (FREE)
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Last Updated on August 7, 2026 by Tomislav Zlatic.
