Phase Fiasco Annulus: a free MI Rings-based resonator Synthesizer plugin - June 12, 2026

Phase Fiasco Annulus is a new free Mutable Instruments Rings-based polyphonic resonator Synthesizer plugin for macOS and Windows.

Mutable Instruments’ algorithms have been open-source for many years. After MI went out of business, there was a flood of new hardware and software that utilized the codes.

Phase Fiasco, the Swedish developer of the lovely free Tape Fiasco plugin, is now also using Emilie Gillet’s code in the new Annulus Synthesizer plugin.



Phase Fiasco Annulus
Annulus is a new polyphonic resonator Synthesizer plugin for macOS and Windows. According to Jonas Eriksson of Phase Fiasco, Annulus uses a faithful implementation of the physical modeling engine behind Mutable Instruments’ Rings.

The plugin not only offers Rings in a plugin but also combines them with a full effects chain and a visual interface. Looking at the latter, it’s clear that the developer has chosen a special design. For example, each algorithm has a different color scheme.

Also, the layout of the parameters is different. There are no knobs or sliders. Instead, you have to hover your mouse over the name. There are also no presets. The developer says that it’s built for sound designers who think in texture, no presets.

At its core, Annulus features six MI Ring-based algorithms, each with eight voices spread across the stereo field with velocity and position randomization for organic variation on every hit. The following algorithms are available:

• Morphosis: modal resonator (the original Rings algorithm)
• Sympatheia: sympathetic strings – ensemble in a box
• Bathmos: Karplus Strong string – from wood to metal
• Anomalia: FM voice – ratio walks
• Donisis: quantized sympathetic strings – chord engine
• Antron: string and reverb – ambient string

Each algorithm comes with four macro knobs: Morphe, Aigle, Nothros, and Topos, allowing you to easily shape the engines.



Deeper Sound Design
In the lower section of the Phase Fiasco Annulus Synthesizer, you can find three versatile effects processors.

From left to right, you have Spiral, a stereo tape delay with tempo sync, ping-pong option, wobble modulation, and saturated feedback.

Then, Velvet is an algorithmic reverb with shimmer, diffusion, ducking, and a four-second tail. The last effect in this chain is a distortion with 12 selectable waveshaping models and 2x oversampling, ranging from soft tube warmth to asymmetric fuzz.

The effects give the physical modeling engine the finishing touch. The distortion, in particular, lends the whole thing a very interesting character. It’s a shame you can’t save the settings in presets.

First Impression
Rings repackaged once again. I think the developer has done a great job with the Annulus Synthesizer. I really like the visuals and the additional effects that give the sounds a real boost.

Phase Fiasco Annulus is available now for free download. It runs as a VST3 and AU plugin on macOS (native Apple Silicon + Intel) and Windows. The plugin is an alpha version and untested.

More information here: Phase Fiasco

Source: https://synthanatomy.com/2026/06/ph...rings-based-resonator-synthesizer-plugin.html

 

Sounds great, love the innovation and will def give it a try! Thanks for the heads up!