Kammerl Beat-Repeat and
Spectral Clouds Effect for
Mutable Instrument's Clouds


This is an alternative firmware for Mutable Instruments Clouds which enables real-time slicing / beat-repeat features ported from the Kammerl Kaske VST plugin suite. In addition v0.4 adds the Spectral Clouds effect, a high-resolution auto-modulated multiband filter.

Note: The original three modes of the official firmware are still present and have been not modified(*). The forth "Spectral Processor" mode has been replaced with the "Spectal Clouds" effect. And this firmware adds a fifth mode to your Clouds module with enables new real-time beat and sound manipulation features.

(*) beside applying the reverb post dry/wet due to repeated request.


See release MIT License notice.

Current Clouds Kammerl Firmware V0.42 WAV file

Change log - Version 0.42

  • Replaces "Spectral Processor" mode with new "Spectral Clouds" mode; a multiband filter effect with randomized band gains to create cloud-like frequency spectras.
  • Adds warm-distortion effect (post dry/wet)
  • Fixes rare crash in Kammerl beat-repeat mode

Change log - Version 0.31

  • Fixes dry/wet control in regular cloud modes

Change log - Version 0.3

  • New features: Alternating loop playback & reverse slice playback
  • Loop size knob now also controls the loop mode
  • Replaces warm distortion effect with previous (v0.1) feedback effect
  • Reverb in regular cloud modes is applied post dry/wet to affect the dry signal
  • Bug fixes: CV control of Blend parameter

Change log - Version 0.2

  • Adds slice selection and slice step feature!
  • Knob reassignment: Pitch Modulation replaces Blend feedback parameter
  • Bug fixes: Warm Distortion bug fixed, Scratch modulation intensity fix

Previous versions:

Source Code:


Note: As with any firmware installation, there is a potential though probably small risk of bricking your device. Proceed at your own risk!

  1. Download the Clouds Kammerl Firmware WAV file.
  2. Unplug all inputs, connect the output of your audio interface to IN L.
  3. Power on the module with the FREEZE button being pushed.
  4. Playback the firmware WAV file - the FREEZE LED will blink.

For more details, see Clouds manual.

Enabling the Kammerl Beat-Repeat or Spectral Clouds mode

Similar to the switching between the alternative modes of the original firmware, hold the B button for 5 seconds until one (or all) of the LEDs glows in orange, and then repeatedly press the button to select one of 5 functions:

  • First LED lit: Granular processor (normal operation).
  • Second LED lit: Pitch shifter/time-stretcher.
  • Third LED lit: Looping delay.
  • All but the fourth LED lit: Spectral Clouds mode.
  • ALL LEDs lit: Kammerl Beat-Repeat mode.

Kammerl Beat-Repeat mode

Note: This mode requires a clock signal plugged into the Trigger input. Without a clock signal, it holds the most recent slice (or outputs silence if no clock signal has been previously provided).

The Kammerl Beat-Repeat mode analyzes the incoming clock signal to enable real-time slicing of the audio input. It manages multiple slices in real-time which can be individually selected. Each slice can be played back with different loop, pitch and distortion settings.



Enables slice processing / beat-repeating. If not enabled, slice processing is randomly enabled based on the blend mode Slice Probability.

Loop Start:

Defines the beginning of the loop interval relative to the total slice duration. To support in-sync beat repetitions, it is quantized as follows: [0-1/64] free/unquantized, 1/64, 1/32, 1/16, 1/8, 1/4, 1/3, 1/2, 1.

Loop Size:

Defines the size of the loop interval relative to the total slice duration as well as the loop mode (regular/alternating). To support in-sync beat repetitions, it is quantized as follows:
  • Regular from the left to 12 o'clock: [0-1/64] free/unquantized, 1/64, 1/32, 1/16, 1/8, 1/4, 1/3, 1/2
  • Alternating from 12 o'clock to the right: 1/2, 1/3, 1/4, 1/8, 1/16, 1/32, 1/64, [1/64-0] free/unquantized


Defines the playback speed. The Kammerl Beat-Repeat mode does not time-correct the pitch changes (like a tape or record running at different speeds). This allows for interesting groove effects, since audio is delayed towards the end of the slice but reset at the slice beginning. To the very left, the knob defines a zero pitch, to the very right, the original playback speed. The pitch modulation is determined by the Pitch Mode knob.

Loop Size Modulation (Density Knob)

Enables a decreasing loop size towards the slice end. This enables a ping-pong bouncing ball effect: Tak tak tak taktak tatatatatttttttt

Texture CV

Selects one of the eight most recently recorded slices. 0V corresponds to the most recent slice (real-time / no delay!). Note that slices are continously created from audio input, independent from FREEZE or slice probability mode.

Slice Step (Texture Knob)

The Texture CV and the Slice Step control different slice selection parameters. The Texture CV directly selects one of the most recently recorded slices. In contrast, the Slice Step parameter selects individual iteration patterns to jump between slices during playback (which also incorporates the Texture CV slice selection by using it as an offset)
  • Disabled - Only Texture CV selects slices
  • Slice step 1 - Repeats current slice due to synced playback index
  • Slice step 2 - Skips every second slice
  • Slice step 3 - Skips two slices
  • Slice step 5 - Skips four slices
  • Slice step 6 - Skips five slices
  • Slice step 7 - Skips six slices
  • Random - Randomly selects slices

Blend Modes:

Slice Probability:

Defines the probability of disabling bypass and processing an incoming slice. Note that activating the FREEZE button overwrites this setting.

Clock Divider:

Selects a clock divider: 1, 1/2, 1/4, 1/8 which changes the slice lengths accordingly.

Pitch Mode:

Selects one of four pitch modulation modes (from left to right):
  • (left position) Fixed pitch - no modulation.
  • Fixed pitch - reverse playback.
  • Linearly decreasing pitch starting from the original pitch to the selected target pitch (Pitch Knob).
  • Linearly increasing pitch starting from the the selected target pitch (Pitch Knob) to the original pitch.
  • (right position) Simulated vinyl scratching - sinusoidal pitch modulation. The Pitch Knob defines the intensity.


Controls the contribution to Cloud's feedback path. Combined with lower pitch playback, this leads to *amazing* lazer gun effects on drums :)

Spectral Clouds mode

The Spectral Clouds mode creates cloud-like frequency spectras. It is a high-resolution multiband filter with randomly modulated frequency bands. The logarithmic divisions of the frequency spectrum result in a continuously morphing but musical sounding filter. This mode is inspired by this FFT Randomizer project.


Trigger input:

Randomizes the set of active frequency bands and defines their random attenuation intensity. Note that these trigger events can also be simulated with the second blend mode ("Probability of random filter changes").

Frequency band probability:

Defines the probability of a frequency band to become enabled. To the left all frequency bands are disabled. Check out the sweet spot where only a few frequency bands are active.

Frequency band division:

Controls the number of filter bands and their corresponding frequency width. To the left, the frequency spectrum is split into 4 filter bands and to the right into 128 filter bands. All frequency band divisions are applied in logarithmic scale to sound musical.


Pitch shifting applied to the Spectral Clouds output.

Filter Smoothing:

Defines the smoothing intensity on the frequency band division as well as the filter band attenuation changes during "trigger input" events. To the left, filter changes are applied immediately; to the right, the current filter configurations is hold.

Filter texture:

Defines the degree of phase randomization in the frequency domain. This affects mostly waveforms with transients.

Blend Modes:

Dry / wet balance:

Balance between input signal and Spectral Clouds output. Note that the warm distortion effect as well as Cloud's reverb is applied post dry / wet.

Probability of random filter changes:

Defines the chance of simulated "Trigger input" events. To the left, simulated trigger events are disabled and random filter reconfigurations only happen during high trigger input gates.

Warm distortion:

It's back :) Adds a warm sounding distortion effect (applied post dry/wet).


Controls the contribution to Cloud's reverb (applied post dry/wet).