Mutable Instruments Rings Review – Musical Resonating for Eurorack

  • By: Thorsten Meyer
  • Date: Wednesday, 17 July 2019
  • Time to read: 4 min.

Mutable Instruments Rings Review

In this review, we are looking at the Mutable Instruments Rings module. Rings is a physical modeling module in Eurorack format. The module comes with three different forms of synthesis. The module enhances sounds with metallic resonating percussion, plucked or string sounds. Émilie Gillet is Mutable Instruments’ product designer, hardware/software engineer, salesperson, and customer support representative in person – she is a genius.

Mutable Instruments is one of the most recognized and leading Eurorack boutique manufacturer. The company is known for innovative eurorack modules. The modules extend your rack with a broad variety of functions at a fair price. Many modules are available as DIY modules, for some of the most famous ones like Clouds the used market or DIY modules are the only way to go until “Clouds v2” is launched in the future.


The module assimilates Mutable Instruments Elements resonator section and transforms it into Mutable Instruments Rings. The Rings module is all about physical modeling synthesis. You can use Rings as a resonator for sound sources or as its own instrument. When feeding a sound into my Rainmaker and Clouds combination I get a perfect foundation for ambiance and pads sounds. The Resonator module can play in polyphony is comparable to the strumming of a guitar. Special features are that each new note is played on its own virtual string while the beforehand performed note still fades out. You can use the resonator models of Rings with 1, 2 or 4 polyphony voices.

The Sound of Rings

How do Rings change the sound you input into the module? With Rings, you can attach resonating vibrations of for example glass to a tone you feed into the module. Feeding this pleasant tone into a Rainmaker and Reverb and you get instant drones textures. The module can also produce sounds on its own and does not need a source feeding into Rings. Also, try to send the Rings output into its FM input. In a mono world of eurorack Rings can generate mind-blowing stereo sounds, use the ODD and EVEN output ports for two channels. You guessed it I am extremely happy with the Rings module in my rack. I love the resulting brushed, plucked resonating sounds and the color it can give my other VCOs like the Black VCO V2 Review and Black VCO Expander.

Alternate modes and Easter Egg

There are different additional modes available.


Hold the polyphony button for a few seconds. This enables a 3 voice polyphonic mode in which the notes bounce between the ODD / EVEN outputs according to an 8-step rhythmic pattern (O E E O E E O E).

2-op FM aka “It’s still Bessel functions!”

Long press on the model selection button while modal synthesis is active (green).

STRUCTURE = frequency ratio. BRIGHTNESS = FM index. DAMPING = FM index and amplitude decay. POSITION = Feedback path (no feedback at 12 o’clock). IN goes into an envelope follower changing FM index and output amplitude.

“Western chords”

Long press on the model selection button when the sympathetic strings model is active (orange).The sympathetic strings are no longer tuned to perfect fifths or octaves, but instead, to chords. STRUCTURE = chord.


Long press on the model selection button when the non-linear string model is active (red). Adds a reverb, the absorption, and decay of which follow those of the string.

The Easter Egg called is more complex to dial in see for the details of “Disastrous peace” the full description here.

Hacking and Open Source

The source code of Rings is available supporting the MIT license. The code (along with the hardware description files) can be found in the rings directory in our Eurorack modules git repository. Schematics, board layout, BOM and panel drawings can be found in the rings directory in our Eurorack modules git repository. Mutable Instruments released the hardware description files are released under a cc-by-sa-3.0 license. The clones are available in an alternative smaller footprint format. There is a 8 hp version of the 14 hp Rings available.

When I looked into different modules I want when starting my Eurorack Journey Rings was high on the list. My expectations are overachieved and I did buy a second one.

Rating:  Five Out of Five Stars

Mutable Instruments Rings is a must-have when you are into generating very musical textures, backgrounds beds and ambiances for your composition. Just send the resonating sound into some effect modules or plugins in your DAW and you are set. Rings should be part of any ambient & drone system, perfect for a composer or sound designer. I love the sound it can produce and how it shapes the sound from my other modules.

Personally, I got two Rings modules, both build based on Open-source Hardware.

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