Ritual Electronics Miasma
Voltage-controlled distortion with self-oscillating feedback loop and swappable rectification diodes
10 HP Eurorack module
Miasma is a 10HP voltage-controlled distortion with an open feedback loop and interchangeable rectification diodes. The signal hits a Gain stage (up to +20dB) feeding two clipping diodes mounted on a tool-free header, so you can swap diode types — 1N4148, 1N914, BAT42, 1N60, blue LED, plus your own — to reshape the distortion's character (symmetrical or asymmetrical). The OTA-based Feedback VCA mixes the post-distortion signal back into the input with no phase inversion, so even with no input patched the module self-oscillates. A Fdbk Out / Fdbk In normalled pair lets you insert filters, delays, or reverbs into the feedback path for tuned or surreal feedback patches. A Blend control crossfades dry/wet and a Level trimmer compensates for diode-dependent volume changes.
Features
- Voltage-controlled distortion with up to +20 dB of pre-gain
- OTA-based VCA on both Gain and Feedback for clean CV control
- Open feedback loop — Fdbk Out / Fdbk In normalled pair
- Self-oscillates with no input when feedback is high enough
- Interchangeable rectification diodes (header-mounted, no tools needed)
- Ships with six diode types: 1N4148, 1N914, BAT42, 1N60, blue LED, plus a spare
- One diode per waveform polarity — supports symmetrical or asymmetrical clipping
- Bipolar attenuverters on both Gain and Feedback CV inputs
- Front-panel Level trimmer for diode-dependent make-up gain
- Dry/wet Blend control for parallel distortion
- 100k input impedance, 1k output impedance
- Responds extremely well to audio-rate modulation on Gain and Feedback CV
Controls & Jacks (12)
- Feedback — Sets the initial amount of distorted signal feeding back into the distortion circuit. Pushes Miasma into self-oscillation when raised — work
- Gain — Sets the initial amount of gain applied to the input signal — up to +20dB. Higher gain means more distortion intensity but reduces audible f
- Blend — Crossfades between the dry input signal (fully CCW) and the 100% wet distorted signal (fully CW). Use this for parallel distortion or precis
- Gain CV Attenuverter — Bipolar attenuverter for Gain CV input. CW adds CV to the Gain knob position; CCW subtracts. At 12 o'clock no CV is applied. Allows positive
- Fdbk CV Attenuverter — Bipolar attenuverter for Feedback CV input. CW adds CV to the Feedback knob position; CCW subtracts. At 12 o'clock no CV is applied.
- Level — Front-panel trimmer that sets the output volume to compensate for level differences between rectification diode types. Does not affect the d
- Gain CV In — CV input for the Gain parameter. Voltage is scaled by the Gain CV Attenuverter and summed with the Gain knob. Responds well to audio-rate mo
- In — Audio input. 100k impedance. The input signal voltage greatly influences the distortion character — higher input levels produce more aggress
- Fdbk CV In — CV input for the Feedback parameter. Accepts -5/+5V. Voltage is scaled by the Fdbk CV Attenuverter and summed with the Feedback knob. Excell
- Fdbk In — Feedback loop input — receives the signal returning from the feedback path. Normalled to the Fdbk Out jack: when nothing is patched, Miasma
- Out — Main audio output of the distorted/blended signal. 1k output impedance. Carries the Blend mix between dry input and the wet distortion stage
- Fdbk Out — Feedback loop output — sends the post-distortion signal out for external processing. Normalled to Fdbk In, so unpatching simply closes the i
How-To Guides
- Subtle warmth
- Aggressive crunch
- Modulated grit (audio-rate FM)
- Self-oscillating chaos (no input)
- Tuned feedback (filter in the loop)
Explore the interactive Miasma panel on BleepDex — tap any control to learn what it does.
