Sound Radix Radical1 Solo is a free monophonic version of the Radical1 additive Synthesizer plugin for macOS and Windows.
At the end of 2025, Sound Radix released its first Synthesizer, Radical1, an additive synth, as a public beta. The plugin is still under development and has not yet reached version 1.0, but it has gained many new features and refinements.
The latest version 0.9.6, featuring numerous additions, was released at the beginning of August. At the same time, Sound Radix also released the Radical1 Solo, a free version of their flagship additive Synthesizer.
Sound Radix Radical1 Solo
Radical1 Solo is a new, powerful free additive Synthesizer plugin for macOS and Windows. The Solo version is based on the same engine as the Sound Radix Radical1 Synthesizer.
The major difference: it only has a single layer and is monophonic instead of polyphonic. This is not a big limitation because you get all the other things.
The developers write that it comes with the same synthesis engine, including the same oscillators, modulation system, filters, and effects as the paid version.
So the monophonic engine allows you to create basses, leads, and sequencers. The full version is more for the rich, multi-layered sounds, chords, pads, and more.
Modular-Style Engine
It uses an advanced modular-style additive engine that allows you to build sounds from harmonics, which are sculpted, bent, and animated. I’m writing about an “advanced engine” because that’s the case.
Sound Radix Radical1 Solo comes with morphing fluid oscillators and generators that support spectrum drawing and spectral sample resynthesis. As is typical for a flagship additive synth, you also have deep spectral shaping tools, including spectral filters and harmonic modifiers.
The modulation system is also impressive: ultra-fast sample-accurate envelopes, LFOs, and more that are available endlessly and can be routed to every possible parameter. There are also onboard spectral effects designed to bend the harmonic domain and perform spectral transformations.
Alongside these, it hosts a range of MIDI effects, including arpeggiators, sequencers, note-shaping tools, performance tools, and more.
First Impression
Radical1 is a true flagship additive synth that goes super deep. It’s just a little summary of some of the highlights. There are far more features I could mention. The Radical1 Solo is a very welcome gesture from the developers to release a free version of it.
This allows you to examine the engine in detail and decide whether you need polyphony or not. Better than a demo that makes weird noises, dropouts, or farts every 15 minutes.
Sound Radix Radical1 Solo is available now as a free download. It runs as a VST3, AU, and AAX plugin on macOS (native Apple Silicon + Intel) and Windows. It requires a free iLok software account.
More information here: Sound Radix
Little tip for them. Just allow a free download. Setting up accounts is too much for this
Here’s something cool. You can load multiple copies of it in Bitwig’s instrument selector, and then you have your free Radical1.
and your CPU will love it 😉