Make Noise Optomix
Two-channel vactrol Low Pass Gate with natural acoustic character
8 HP Eurorack module
Optomix is a two-channel Low Pass Gate using vactrols to simultaneously control amplitude and frequency content of audio or CV signals, producing natural acoustic-like transients reminiscent of struck drums, plucked strings, and mallet instruments. Its vactrol-based design imparts a characteristically smooth, organic response with moderate attack and slow decay, creating a ringing quality that pairs beautifully with FM and ring-modulated sources. Beyond classic LPG duties, it serves as an envelope generator, slew limiter, audio compressor with sidechain, and CV utility via its offset normalization and DAMP circuit.
Features
- Two independent Low Pass Gate channels using vactrols for simultaneous VCA and VCF control
- DAMP parameter with continuously variable control from long ringing to short muted response
- STRIKE input on each channel accepts 8V gate for plucking/striking the vactrol without an envelope generator
- Audio-rate DAMP CV input enables sidechain compression and ducking effects
- CONTROL and DAMP inputs normalized to +8V for use as offset/level controls when nothing is patched
- Channel Signal inputs normalized with positive offset for CV processing and envelope generation
- SUM output mixes both channel outputs plus AUX input for larger mix configurations
- AUX input allows chaining multiple Optomix or modDemix units
- Channel 1 Signal OUT is NOT normalled to Channel 2 Signal IN (revised from original Optomix)
- Can function as slew limiter with DAMP controlling fall time
- Direct-coupled throughout for use with both audio and CV signals
- DAMP Combo Pots act as unipolar attenuators when CV is patched, or as manual controls when nothing is patched
Controls & Jacks (18)
- Signal In 1 — Audio or CV input for Channel 1 LPG. Normalled with positive offset for CV processing when unpatched.
- Damp CV 1 — CV input for Channel 1 Damp (0-8V). Normalled to +8V. Accepts audio-rate signals for sidechain compression effects.
- Control In 1 — CV input controlling Channel 1 vactrol response (0-8V). Normalled to +8V so the Control 1 knob works as a manual level.
- Damp 1 — Controls the decay time of Channel 1 vactrol response. CW shortens decay for muted hits; CCW lengthens for ringing resonance.
- Control 1 — Sets the vactrol drive level for Channel 1. Acts as a CV attenuator when Control In 1 is patched, or as a manual offset (0-8V) when unpatche
- AUTO1 — Dedicated output for Channel 1 after processing through the vactrol LPG circuit.
- Strike In 1 — Gate input (8V) that plucks Channel 1 vactrol for percussive hits without needing an external envelope.
- Signal Out 1 — Output of the signal applied to Channel 1 input, as processed by the LPG. Up to 10Vpp.
- Signal In 2 — Audio or CV input for Channel 2 LPG. Normalled with positive offset for CV processing when unpatched.
- Control In 2 — CV input controlling Channel 2 vactrol response (0-8V). Normalled to +8V so the Control 2 knob works as a manual level.
- Damp CV 2 — CV input for Channel 2 Damp (0-8V). Normalled to +8V. Accepts audio-rate signals for sidechain compression effects.
- Control 2 — Sets the vactrol drive level for Channel 2. Acts as a CV attenuator when Control In 2 is patched, or as a manual offset (0-8V) when unpatche
- Damp 2 — Controls the decay time of Channel 2 vactrol response. CW shortens decay for muted hits; CCW lengthens for ringing resonance.
- Signal Out 2 — Output of Channel 2 after processing through the vactrol LPG circuit.
- AUTO2 — Dedicated output for Channel 2 after processing through the vactrol LPG circuit.
- Strike In 2 — Gate input (8V) that plucks Channel 2 vactrol for percussive hits without needing an external envelope.
- Aux In — Direct-coupled input feeding the SUM circuit, bypassing both LPG channels. Used to chain multiple Optomix or modDemix units.
- Sum Out — The SUM or mix of all signals processed by the Optomix. Up to 10Vpp.
How-To Guides
- Basic Percussive LPG Hit
- FM Pings
- Optomix as Envelope Generator
- Kick Drum Sidechain Ducking
- Palm Mute Emulation
- Accented Sequencing with DAMP
- The New Bongo
- Simple Slew Limiter
- Expanded Mix with Multiple Optomix Units
- Dynamic FM Modulation Bursts
Explore the interactive Optomix panel on BleepDex — tap any control to learn what it does.
