Mystic Circuits — IDUM
IDUM Official Manual (PDF)
Mystic Circuits IDUM — Eurorack Cheat Sheet
IDUM is an intelligent gate/trigger manipulator designed to add probability, ratcheting, clock mangling, and live performance tricks to sequenced rhythms. It’s like an “effects processor” for your gates/triggers.
Panel Reference
Inputs
| Jack |
Type |
Function |
Voltage Range |
| CL |
Clock In |
External clock |
0–5V (Trig ≥ ~1.8V) |
| TR1–TR4 |
Trigger In |
4 external triggers/gates |
0–5V (Trig ≥ ~1.8V) |
| CHANCE |
CV Input |
Probability CV |
0–5V |
| MODE |
CV Input |
Mode Selection CV |
0–5V |
| PARAM |
CV Input |
Parameter CV |
0–5V |
| LENGTH |
CV Input |
Modification length CV |
0–5V |
| LOOP |
Gate Input |
Toggles loop mode (see Setup) |
0–5V |
Outputs
| Jack |
Type |
Function |
Voltage Range |
| CL |
Clock Out |
Modified clock out |
0–5V |
| TR1–TR4 |
Trigger Out |
4 processed gate/trigger outs |
0–5V |
Modes Summary (Selected by MODE Knob)
- Hold — Probabilistically lengthen (CW) or skip/mute (CCW) incoming triggers.
- Burst — Ratchets: Get fast bursts of triggers when a gate is received. PARAM = div/mult of clock.
- Multiply/Divide — Ratchets based on distance between IN triggers. PARAM = div/mult of last trigger interval.
- Bouncing Ball — Triggers speed up (CCW) or slow down (CW), simulating a bouncing ball (unquantized).
- Rotate — Scrambles connections between triggers in/out. PARAM = Swap (CCW) or Rotate (CW).
- Gate Delay — Delays outputs based on recent intervals. PARAM = Delay % (side to side applies delay per channel).
- Break — Selects preset breakbeat-style rhythms (16 patterns via PARAM).
- Skip — Manipulates clock only (not triggers): Step skipping (CCW), Clock ratchet (CW).
All modes: CHANCE slider sets probability of effect activating (0–100%), LENGTH sets modification length (1–8 clocks), PARAM function is mode-dependent. GATE/Trigger out is active 0–5V.
Control Summary
| Control |
Type |
Action/Behavior |
| MODE |
Large Rotary |
Select active modification mode |
| PARAM |
Small Rotary |
Mode-specific parameter (see table above) |
| LENGTH |
Slider |
Duration (steps) of modification (1–8, can be CV controlled) |
| CHANCE |
Slider |
Probability mod applies (0–100%, can be CV controlled) |
| REMOVE MODE |
Button (top left) |
Tap: Remove (bypass) current mode · Long: Enter Setup menu |
| LOOP |
Button (center) |
Tap: Toggle looper on/off (or use Loop CV input) |
| CYCLE |
Switch (2-position) |
Up: “Tracks” original clock position (for sequencer sync), Down: Output can drift out of sync |
Output LEDs
- Blue = Incoming trigger detected
- Red = Modified trigger outputting
- Pink = Output is pass-through (not modified)
Looper Mode
- LOOP Button/Input: Capture and repeat last 8 steps of triggers + mods. Button toggles loop, input can toggle/momentary (set up in menu).
- While loop is active, panel controls adjust playback parameters:
- MODE: Choose first step (“scrub” steps when length=1)
- PARAM: Loop speed
- LENGTH: Loop length (1–8)
- CHANCE: Probability that the stored mod is applied on each step
Setup Menu (Long Press REMOVE MODE)
Setup options can restrict step/parameter values, clock bursts, and loop gate behavior.
- Parameter/Length Resolution: ODD/EVEN/POW2 steps only
- Slow Clock: Slower clock burst for digital sequencers (LED off = slow)
- 16 Step: (future) Expand to 16 steps
- Split: (future) Per-channel mode independence
- Loop: Set LOOP input to latching (default) or momentary (LED on)
Cheat Sheet: Using IDUM
- Connect clock/gates and patch outputs to drums, synth, or sequencer.
- Set CHANCE slider up for more effects, down for subtlety.
- Set LENGTH slider for how many steps effect stays on.
- Turn PARAM knob to mode-specific setting.
- Select mode with MODE knob; tap REMOVE MODE to bypass undesired modes.
- Engage LOOP with center button or gate for live remixing.
- Use CYCLE switch up if synchronizing a sequencer to clock out.
For firmware updates, use micro-USB on rear; see the manual or Mystic Circuits GitHub for details.
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