Instruo Ceis
Fully analogue VC-ADSR with per-stage gate outputs
8 HP Eurorack module
The Instruō cèis is a fully analogue voltage controlled ADSR envelope generator with individual gate outputs for each stage and voltage control over every parameter. It excels at classic East Coast subtractive synthesis but extends the format with per-stage gate outputs, a combined trigger output, and a morphable linear-to-logarithmic shape control, making it a versatile modulation source beyond simple amplitude shaping.
Features
- Fully analogue voltage controlled ADSR envelope generator
- Voltage control over every stage (Attack, Decay, Sustain, Release)
- Individual gate outputs for each envelope stage (Attack, Decay, Sustain, Release)
- Combined trigger output that fires at the beginning of each envelope stage
- Linear to logarithmic/exponential shape morphing via Shape knob
- Manual gate/trigger button with LED that illuminates according to envelope contour
- Two envelope reset modes: Gate Mode and Trig Mode via toggle switch
- CV output range 0–10V
- Gate/Trig input voltage threshold 3V
- Attack time range approximately 3ms to 10s (down to ~0.4ms with negative CV)
- Decay time range approximately 3ms to 12s (down to ~0.4ms with negative CV)
- Release time range approximately 3ms to 12s (down to ~0.4ms with negative CV)
Controls & Jacks (21)
- Attack Gate Output — Gate signal high for the duration of the attack stage (10V)
- Decay Gate Output — Gate signal high for the duration of the decay stage (10V)
- Sustain Gate Output — Gate signal high for the duration of the sustain stage (10V)
- Release Gate Output — Gate signal high for the duration of the release stage (10V)
- Attack CV Input — Unipolar positive control voltage summed with Attack fader (0.4ms-10s range with negative CV)
- Decay CV Input — Unipolar positive control voltage summed with Decay fader (0.4ms-12s range with negative CV)
- Sustain CV Input — Unipolar positive control voltage summed with Sustain fader (0V-10V range)
- Release CV Input — Unipolar positive control voltage summed with Release fader (0.4ms-12s range with negative CV)
- OUT LED — Visual indicator showing the envelope output level
- Retrig Input — Retrigger input for restarting the envelope mid-cycle
- Combined Trigger Output — Generates trigger signals at the beginning of each envelope stage (10V)
- CV Output — Main envelope control voltage output (0V-10V)
- Env Output — Secondary envelope output
- Gate/Trig Input — Receives gate or trigger signals to start the envelope (3V threshold)
- Shape — Controls envelope contour response from linear (anticlockwise) to logarithmic/exponential (clockwise)
- Gate/Trig — Manual gate/trigger button that illuminates to represent the contour of the generated envelope signal
- Attack — Defines the onset duration of the envelope (3ms-10s). Fader down increases speed, fader up decreases speed
- Decay — Defines time to reach sustain stage after attack (3ms-12s). Fader down increases speed, fader up decreases speed
- Sustain — Defines resting voltage level after decay stage (0V-10V). At minimum the envelope becomes AD, at maximum it becomes ASR
- Release — Defines time to reach 0V after sustain stage (3ms-12s). Fader down increases speed, fader up decreases speed
- Mode Select — Three-position switch: HOLD, GATE, and TRIG modes for different envelope behavior
How-To Guides
- Classic ADSR Envelope Setup
- Percussive AD Envelope
- Slow Pad Swell
- Vibrato Swell
- Burst Generator
- Per-Stage Gate Sequencing
- Tempo-Synced Attack and Decay via CV
- East Coast Synth Voice
- Trig Mode AR Pluck
- ADSR as Clock Divider or Multiplier
Explore the interactive Ceis panel on BleepDex — tap any control to learn what it does.
