Github - BOM

Features

Audio buffer acquisition

• Stereo I/O. Even with a mono recording buffer, a wide stereo output can still be simulated by randomly panning grains or through the stereo reverberator.
• Stereo pre-amp with a gain range covering modular and line levels.
• Recording buffer size: 1s (32kHz, stereo) to 8s (16kHz, µ-law, mono).
• The FREEZE button and the corresponding gate input freezes the content of the recording buffer, allowing you to dive into its sonic details.
• 4 memory slots for storing and recalling buffers.

Granular synthesis

• Grain generation time base: periodical, randomized, or externally clocked.
• The POSITION knob selects from which part of the recording buffer the grains are extracted.
• Grain size from 16ms to 1s.
• Up to 40 to 60 concurrent grains (depending on recording buffer resolution).
• Transposition from -2 octaves to +2 octaves, with V/O tracking.
• Grain envelope continuously variable between boxcar, triangle and Hann functions.
• CV inputs for all grain parameters, individually sampled and held by each grain. For stochastic, Xenakis-style explorations, try feeding random voltages to those!
• Diffusion network with 4 All-pass filters to post process the granularized signals.

Post-processing ("blending") settings

4 post-processing parameters are controlled by the BLEND knob and CV input:

• Dry/wet balance.
• Random panning amount.
• Feedback amount.
• Reverb amount.

Specifications

• Input impedances: 100k.
• Audio input gain range: line level to modular level.
• CV range: +/- 5V. CVs outside of this range are simply clipped.
• Internal processing: 32kHz, 32-bit floating point. RAM Recording buffer uses 16-bit (high quality) or 8-bit µ-law (low quality) resolution.

Code (AVR projects): GPL3.0.

Code (STM32F projects): MIT license.

Hardware: cc-by-sa-3.0

By: Emilie Gillet (emilie.o.gillet@gmail.com)

Cirrus pcb

MMI Modular rework of Mutable Instruments Clouds pcb 

• Replaced plastic gain potentiometer with dual gang Alpha style A50k potentiometer. These can be found here
  
• Changed all 10uF capacitors to the Panasonic B footprint. Dimensions can be found here
  
• Moved some capacitors around to make hand soldering easier
  

Cirrus is my rework of the popular Clouds module, originally designed by Emilie Gillet of Mutable Instruments. After building several Clouds myself, I found several problems that were easy to fix with a simple PCB revision. I decided it would be worth the effort, so here it is.

This pcb fits the standard Clouds panel