Octatrack MKII Architecture Overview
Elektron
Elektron Octatrack MKII
Identity
- Manufacturer: Elektron
- Type: Dynamic performance sampler
- Tracks: 8 stereo audio + 8 MIDI
- Audio I/O: 4 in (2 stereo pairs) / 4 out (main L/R + cue L/R) + headphones
- Sequencer: 64-step per track, micro timing, conditional trigs, parameter locks
- Storage: Compact Flash card (up to 64 GB)
- RAM: 80 MB (shared across 128 Flex sample slots)
- Year: 2017 (MKII), original MKI 2011
- OS: 1.40A+
What Makes It Special
The Octatrack is not a sampler in the traditional sense -- it is a performance instrument that happens to use samples. Where most samplers separate recording and playback into distinct modes, the OT integrates them seamlessly under one sequencer. You can record, mangle, and play back audio without ever stopping the clock.
Its power comes from three interlocking systems:
-
The Parts system -- Separates "what sounds play" (machines, effects, scenes) from "when they trigger" (patterns). Multiple patterns can share a single Part, creating coherent variations. Switch Parts for radical timbral shifts without losing your place.
-
Scenes + Crossfader -- Assign parameter snapshots to the crossfader's A and B sides. Fade smoothly between two completely different states of your mix. 16 scenes per Part, assignable on both sides. This is the OT's primary live performance tool.
-
Five machine types -- Each audio track hosts one machine:
- Flex: Plays samples from RAM (80 MB shared). Instant, glitch-free, supports real-time manipulation
- Static: Streams samples from CF card. Supports files up to 2 GB. Good for backing tracks and long recordings
- Thru: Passes external audio input through the track's effects chain. Makes the OT an effects processor
- Neighbor: Listens to the previous track's output. Chain multiple effects in series
- Pickup: Looper machine. Record, overdub, multiply, reverse. The OT's live looping engine
Curriculum Focus
This curriculum emphasizes the Octatrack as a songwriting and live performance tool:
- Songwriting: Building compositions from samples, loops, and live recordings. Using patterns as song sections, banks as songs, and the Arranger for long-form structure
- Live looping: Pickup machines for real-time recording and layering. Thru machines for live processing. Track recorders for capturing and re-deploying audio on the fly
- Improvisation: Scenes for fluid parameter morphing. Parts for radical timbre shifts. Parameter locks for step-by-step variation. Conditional trigs for generative patterns that evolve over time
Data Hierarchy
Set (top level, lives on CF card)
└── Audio Pool (shared samples across all projects)
└── Project (the working context)
├── Flex Sample Slots (128, loaded into RAM)
├── Static Sample Slots (128, streamed from CF)
├── 8 Track Recorders (one per audio track, write to record buffers in sample slots)
├── 8 Arrangements (song mode sequences)
└── 16 Banks (A-P)
├── 16 Patterns per bank (256 total)
│ ├── Triggers + parameter locks (per step)
│ └── Points to a Part (1-4)
└── 4 Parts per bank
├── Machine assignments (what machine type + sample per track)
├── Track parameter settings (pitch, amp, LFO, FX1, FX2)
├── Effect assignments (which effect on FX1/FX2 per track)
├── 16 Scenes
└── Track volume settings
Key Concepts for Newcomers
Patterns store triggers. Parts store sounds.
This is the single most important concept. A Pattern holds the sequencer data (which steps trigger, parameter locks). A Part holds the "infrastructure" (machines, effects, scenes, volumes). Multiple patterns can share the same Part -- changes to the Part affect all patterns using it.
The sample slot list is project-wide
Samples are loaded into a Flex or Static slot list once, then available everywhere in the project. Any flex machine on any track in any pattern can access any sample in the flex list. Sample locks let you swap samples on individual steps.
Scenes are the performance interface
The crossfader interpolates between Scene A and Scene B. Load different scenes to each side, slide the fader, and parameters morph smoothly. Scenes can control any track parameter including volume (XLEV/XVOL), creating smooth fades, buildups, and transitions.
Recording never stops the clock
Track recorders, pickup machines, and the sequencer all run simultaneously. You can record external audio, internal audio, or the cue mix while patterns play. Recorded material lands in the sample slot list and is instantly available to any flex machine.
Physical Controls
Front Panel (30 controls)
- Volume knob: Main output level (FUNC + Volume = track level)
- Headphones Vol: Headphone level
- 6 Data Entry knobs (A-F): Map to the 6 on-screen parameters
- Level knob: Active track volume (FUNC = master volume)
- Crossfader: Interpolates between Scene A and Scene B
- 8 Track keys (T1-T8): Select active track / trigger machines
- 16 Trig keys (1-16): Place triggers, select patterns/banks/scenes
- Transport: Play, Stop, Record
- Navigation: Arrow keys (Up/Down/Left/Right), Yes, No
- Function keys: FUNC, PROJ, PART, AED, MIX, ARR, MIDI
- Track Parameter keys: SRC, AMP, LFO, FX1, FX2
- Scene A / Scene B keys: Assign scenes to crossfader sides
- Pattern / Bank / Page keys: Pattern selection
- REC1, REC2, REC3: Track recorder controls
- CUE key: Route tracks to cue output
- Tempo key: BPM control and tap tempo
Rear Panel (11 connections)
- Power switch + DC In (12V)
- USB (computer connection, USB disk mode)
- Compact Flash card slot
- MIDI In, Out, Thru
- Input C/D + Input A/B (1/4" mono, balanced capable)
- Cue Out L/R (1/4" mono)
- Main Out L/R (1/4" mono)
- Headphones (1/4" stereo)
Key References
- Octatrack MKII User Manual (Elektron, OS 1.40A) -- Official reference for all parameters, menus, and operations
- "Some Thoughts on Elektron's Octatrack" by Merlin (edited by Thermo) -- Community guide that builds understanding from the ground up, especially strong on Parts, Scenes, sampling workflow, and volume handling
Signal Flow
Octatrack MKII Signal Flow
Audio Path Overview
The Octatrack's signal flow has three layers: external inputs, internal tracks, and outputs.
EXTERNAL INPUTS INTERNAL TRACKS OUTPUTS
Input A/B ──→ [Gain] ──→ [DIR] ───────────────────────────────→ Main Out L/R
│ │ ↑
│ ├──→ [Scenes/XDIR] ──→ Main Out │
│ │ │
│ └──→ Track Recorders │
│ │ │
Input C/D ──→ [Gain] ──→ [DIR] ──→ │ ──────────────────→ Main Out L/R
│ │ │ ↑
│ ├──→ Scenes│ │
│ │ │ │
│ └──→ Track Recorders │
│ │
▼ │
┌──────────────────────────────────────────────┐ │
│ PER-TRACK CHAIN (x8) │ │
│ │ │
│ [Machine] → [Amp Env] → [FX1] → [FX2] → ──┼──→ Main Out
│ ↑ │ VOL │ │ │ │
│ │ │ │ │ │ or │
│ Sample from ↑ ↑ ↑ │ │
│ slot list XVOL (scene- Track │ Cue Out L/R
│ or input (scene) controlled) Volume │
│ or neighbor params (XLEV) │
└──────────────────────────────────────────────┘
Per-Track Signal Flow (Detailed)
Each of the 8 audio tracks follows this path:
Scene-controlled
parameters (XVOL, XLEV)
│ │
▼ ▼
Machine ──→ Amp Envelope ──→ [XVOL] ──→ FX1 ──→ FX2 ──→ Track Volume ──→ [XLEV] ──→ Output
│ │ │
│ VOL param Level knob
│ (-64 to +63) (or track
│ vol in Part)
│
├── Flex Machine (sample from RAM)
├── Static Machine (sample from CF card)
├── Thru Machine (external input A/B or C/D)
├── Neighbor Machine (previous track's output)
└── Pickup Machine (looper -- records and plays back)
Volume Architecture (Critical for Live Use)
The OT has four volume stages per track. Understanding these prevents the most common mixing headaches:
- Sample Gain (Audio Editor > Attributes > GAIN): Corrects the source sample's level. Set once, affects the sample everywhere. Range: +/- 24 dB
- Amp Volume (AMP page > VOL): Pre-FX volume. Bipolar (-64 to +63, default 0). Good for tremolo via LFO modulation
- Track Volume (Level knob / Part-stored): Post-FX volume. The main mixing control
- Scene Volumes (XVOL and XLEV): Scene-exclusive parameters.
- XVOL: Pre-FX volume control via scene (same point as Amp VOL)
- XLEV: Post-FX volume control via scene (same point as Track Volume)
Why this matters: If you fade out a track using XVOL, the reverb/delay tails die naturally. If you fade using XLEV, you also fade the FX tails. Choose based on musical intent.
Input Signal Flow
┌─────────────────────────────────┐
Input A/B ──→ [GAIN] ──→ │ DIR ──────────────→ Main Out L/R │
│ │ ↑ │
│ │ XDIR (scene-controlled) │
│ │ │
│ │ To Track Recorders ──→ Record │
│ │ (any combination of Buffers │
│ │ A/B, C/D, track, (in sample │
│ │ main, or cue) slot list)│
│ │ │
Input C/D ──→ [GAIN] ──→ │ DIR ──────────────→ Main Out L/R │
└─────────────────────────────────┘
GAIN (Mixer page): Boosts or suppresses incoming signal by up to 12 dB. Set once at the start of a project to normalize input levels. Not automatable.
DIR (Mixer page): Controls how much input signal goes directly to main outs. Independent of track processing.
XDIR (Scene-controlled): Allows scenes to fade inputs in/out via crossfader without touching the Mixer page. Essential for live performance.
Recording Signal Flow
Each of the 8 tracks has its own Track Recorder that writes to a dedicated Record Buffer in the sample slot list.
Sources: Track Recorder Destination:
│
Input A/B ────────→ │
Input C/D ────────→ [Recorder N] ────→ Record Buffer N
Any Track ───────→ │ (in Flex sample
Main Out ────────→ │ slot list)
Cue Out ────────→ │
│
Trigger methods:
• Sequencer trig (quantized, repeatable)
• One-shot trig (record once, stop)
• Manual (press REC + TRACK)
• Quantized manual (QREC/QPL settings)
Key insight: Record buffers live in the sample slot list. Once audio is recorded, it is instantly available to any flex machine anywhere in the project. No preparation step needed.
Pickup Machine Signal Flow
Pickup machines have their own recording signal path, independent of track recorders:
Input A/B or C/D ──→ [Pickup Machine] ──→ Loop Buffer
│ │
│ ┌────────────────┘
│ │
▼ ▼
[Overdub / Multiply]
│
▼
Loop Playback ──→ FX1 ──→ FX2 ──→ Output
Pickup machines support:
- Master/Slave: One pickup sets the loop length, others sync to it
- Overdub: Layer new audio on top of existing loop
- Multiply: Double the loop length while recording
- Reverse: Flip playback direction
- Half-speed: Halve playback speed (doubles pitch down)
Neighbor Machine Chaining
Neighbor machines create effects chains by routing one track's output into the next:
Track 1 (Flex) ──→ FX1 ──→ FX2 ──→ Output
│
▼
Track 2 (Neighbor) ──→ FX1 ──→ FX2 ──→ Output
│
▼
Track 3 (Neighbor) ──→ FX1 ──→ FX2 ──→ Output
This gives up to 6 chained effects (3 tracks x 2 FX slots) on a single audio source. The trade-off is using multiple tracks for one sound.
Output Routing
┌─────────────┐
Track 1-8 ────────→ │ Main Out │ ──→ Main Out L/R
│ (default) │
└─────────────┘
│
┌──────┴──────┐
Track 1-8 ────────→ │ Cue Out │ ──→ Cue Out L/R
(when CUE+TRACK │ (headphones │ (or headphones)
is pressed) │ preview) │
└─────────────┘
- Main Out: Default destination for all tracks. Controlled by FUNC + Level
- Cue Out: Independent output for previewing, submixing, or routing to track recorders. Press CUE + TRACK to toggle
- Headphones: Can be set to Main, Cue, or Main+Cue in the Mixer menu