wavetable_envelopes

Wavetable Envelopes (WT Env), Wavetable LFOs (WT LFO), and Envelope Step FX (w / y)

This guide explains how Wavetable Envelopes (WT Env), Wavetable LFOs (WT LFO), and the Envelope Pattern Step FX (w and y) work on the Polyend Tracker, Tracker Mini, and Tracker+, as well as how to load custom user wavetables from your SD card.

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1. Getting Started: Selecting WT Env or WT LFO

1. Select any sample-based instrument and press Instrument Parameters twice to open Instrument Automation (2/2).
2. In the first column (Destination), select any of the 7 modulation targets:
   • Volume
   • Panning
   • Cutoff
   • Wavetable Position
   • Granular Position
   • Granular Length
   • Finetune
3. Move to the second column (Type) and choose:
   • WT Env - One-shot or sustain-freezing multi-segment wavetable envelope triggered on each Note On.
   • WT LFO - Tempo-synced looping wavetable LFO that continuously cycles through the selected wavetable shape.

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2. Parameter Reference

WT Env (Wavetable Envelope)

Column	Parameter	Range	Description
3	Wave	F 001 – F 128 U 001 – U 128	Selects one of 128 Factory (F) or 128 User (U) wavetable contours. Pressing Up ([+]) increases the wave number; Down ([-]) decreases it.
4	Duration	0.000s – 20.000s	Total time for the envelope to travel from the start (0%) to the end (100%) of the wavetable contour.
5	Warp X/Y	-7 to +7 / -7 to +7	Dual-axis contour shaper displayed as a split bipolar bar from the center zero line: • Left bar (Warp X, -7..+7): Time-warps the horizontal phase axis. Negative values compress features toward the attack (fast start, drawn-out tail); positive values delay features toward the end (slow build, fast finish). • Right bar (Warp Y, -7..+7): Bends the vertical amplitude curve. +1..+7 boosts quiet/mid levels upward; -1..-6 pinches levels downward for sharper transients; -7 inverts the entire contour upside down (1.0 - y).
6	Sustain	Off, 1% – 99%	Controls how note length affects the envelope: • Off (0): True one-shot mode. The contour plays through its full Duration regardless of when Note Off occurs. • 1% – 99%: Timeline freeze point. While a note is held, the envelope plays up to the chosen percentage of the wavetable timeline and holds that exact level. When the note is released (Note Off), the envelope resumes from that point to the end of the wavetable.
7	Amount	0% – 100%	Modulation depth applied to the destination parameter.

Adjusting Warp X/Y in WT Env

Because WT Env packs both Warp X and Warp Y into Column 5 (Warp X/Y):

• Original Tracker & Tracker+:
  • Warp X: Turn the Jog Wheel or press Arrow Up / Down.
  • Warp Y: Hold Shift + Jog Wheel or Shift + Arrow Up / Down.
• Tracker Mini:
  • Warp X: Press Arrow Up / Down or [+] / [-].
  • Warp Y: Hold Shift + Arrow Up / Down or press [++] / [--].
• Reset: Pressing Delete on Warp X/Y resets both Warp X and Warp Y to +0 / +0.

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WT LFO (Wavetable LFO)

Column	Parameter	Range	Description
3	Wave	F 001 – F 128 U 001 – U 128	Selects the wavetable shape cycled by the LFO.
4	Speed	128 steps – 1/64 step (Volume: down to 1/6 step)	Tempo-synced LFO cycle rate in pattern steps.
5	Warp X	-7 to +7	Horizontal time-skew of the LFO cycle (displayed as a center-zero bipolar bar).
6	Warp Y	-7 to +7	Vertical amplitude bend of the LFO cycle (-7 inverts the waveform upside down).
7	Amount	0% – 100%	Modulation depth applied to the destination parameter.

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3. Pattern Step FX: w - WT Volume Env & y - WT Filter Env

Two pattern Step FX (located right after J - Slide down and before the MIDI CC / Macro effects a–f) allow per-step expressive control over the Volume Envelope (w - WT Volume Env) and Filter Cutoff Envelope (y - WT Filter Env) using a compact 2-digit hexadecimal value XY (00 – FF), where:

• X (0 – F, high hex digit) controls the first parameter.
• Y (0 – F, low hex digit) controls the second parameter.

The behavior of w and y adapts automatically depending on whether the instrument's Volume or Cutoff automation Type is set to a standard ADSR Envelope or a WT Env:

A. When Type is WT Env (XY = Duration Scale / Warp X Offset)

• X (First Hex Digit, 0–F): Scales the WT Env Duration for that step (8 = neutral 1.0× instrument Duration):
  • 0 = 0.05× (ultra-short percussive blip)
  • 2 = 0.19× (~5× faster than default)
  • 4 = 0.36× (~3× faster)
  • 6 = 0.62×
  • 8 = 1.00× (unchanged instrument Duration)
  • A = 1.44×
  • C = 2.06× (~2× longer)
  • E = 2.91× (~3× longer)
  • F = 4.00× (4× longer than instrument Duration)
• Y (Second Hex Digit, 0–F): Offsets Warp X for that step (8 = neutral +0 offset):
  • 0 / 1 = -7 (maximum skew toward start)
  • 4 = -4
  • 8 = +0 (unchanged instrument Warp X)
  • C = +4
  • F = +7 (maximum skew toward end)

Examples with WT Env on Cutoff (y):

• y88 - Plays the WT Env with its exact programmed Duration (1.0×) and Warp X (+0).
• y28 - Plays the WT Env ~5× faster (0.19× Duration) with unchanged Warp X (+0).
• y82 - Keeps the programmed Duration (1.0×) but skews Warp X by -6 for a snappier front-loaded contour.
• yC4 - Doubles the Duration (2.06×) and skews Warp X by -4.

B. When Type is Standard Envelope (ADSR) (XY = Attack / Decay-Release)

• X (First Hex Digit, 0–F): Sets the Attack time on an exponential curve from 0 ms (0) up to 10,000 ms (F).
• Y (Second Hex Digit, 0–F): Sets the Release time on an exponential curve from 5 ms (0) up to 10,000 ms (F). Additionally, when X = 0 (zero attack), Y also scales the Decay time so w01–w0F / y01–y0F can shape tight percussive plucks on a single step.

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4. Factory (F 001–F 128) vs. User (U 001–U 128) Wavetables

The Tracker stores 256 wavetable shapes (each represented as a 128-point, 16-bit unipolar contour in external SDRAM):

UI Range	Slot Count	Source
F 001 - F 128	128	Factory Wavetables - Built into the firmware (8 banks of 16 musical contours).
U 001 - U 128	128	User Wavetables - Loaded from the /Envelopes folder on your SD card, with built-in fallback shapes for any slot that does not have a corresponding .wav file on disk.

Built-In Factory Banks (F 001 – F 128)

• F 001 – F 016: Exponential & logarithmic decays / percussive plucks
• F 017 – F 032: Smooth swells, S-curves & Gaussian bells
• F 033 – F 048: Double & multi-bounces (damped elastic arcs)
• F 049 – F 064: Rhythmic gates & trance steppers (50% and 25% duty cycles)
• F 065 – F 080: Sharks, fins & asymmetric triangles
• F 081 – F 096: Ripples & exponentially damped oscillations
• F 097 – F 112: Accelerating & decelerating trills (chirp gates)
• F 113 – F 128: Staircases up & down

Built-In Fallback Banks for User Slots (U 001 – U 128)

So that U 001 – U 128 are immediately useful even when /Envelopes does not exist on the SD card (or when you only place a handful of custom .wav files), all 128 user slots are pre-initialized at boot with 8 additional procedural banks:

• U 001 – U 016: West-Coast wavefolded contours
• U 017 – U 032: Syncopated binary pulse patterns
• U 033 – U 048: Reverse swells with snappy cutoffs
• U 049 – U 064: Dual-peak camel / formant contours
• U 065 – U 080: Growing chaos / rising frequency wobble
• U 081 – U 096: Karplus-style rippled plucks
• U 097 – U 112: Stepped sample-and-hold (S&H) contours
• U 113 – U 128: Cinematic morphing risers

When you place a .wav file in /Envelopes for a given slot (e.g., 001.wav), it overwrites U 001 while leaving any other U xxx slots without .wav files on their built-in fallback shapes.

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5. How to Add Your Own Wavetables in /Envelopes

Step 1: Create the /Envelopes Folder on Your SD Card

At the root level of your Tracker SD card, create a folder named Envelopes (case-insensitive on FAT32):

SD Card Root/
├── Envelopes/
│   ├── 001.wav      --> Loaded into U 001
│   ├── 002.wav      --> Loaded into U 002
│   ├── ...
│   └── 128.wav      --> Loaded into U 128
├── Firmware/
├── Projects/
└── Samples/

Step 2: Name Your .wav Files

• 1-Based Numbering (Recommended - matches UI labels U 001 to U 128 directly):
  • Use 3-digit zero-padded numbers: 001.wav through 128.wav (unpadded names like 1.wav through 128.wav also work).
  • 001.wav maps to U 001, 002.wav maps to U 002, ..., 128.wav maps to U 128.
  • You can populate as few or as many slots as you like. For example, placing only 001.wav and 005.wav will replace U 001 and U 005.
• 0-Based Numbering (Also Supported):
  • If /Envelopes/000.wav (or 0.wav) is present, the loader automatically uses 0-based indexing (000.wav $\rightarrow$ U 001, 001.wav $\rightarrow$ U 002, ..., 127.wav $\rightarrow$ U 128).

Step 3: .wav File Technical Requirements

Your .wav files must meet the following specifications:

1. File Format: Uncompressed PCM .wav (RIFF / WAVE, AudioFormat = 1).
   • Note: Compressed .wav formats or 32-bit IEEE float (AudioFormat = 3) are not supported; export as 16-bit or 24-bit integer PCM.
2. Bit Depth: 8-bit, 16-bit (recommended), or 24-bit integer PCM.
3. Channels: Mono (recommended) or Stereo (if stereo, the left channel is used).
4. Sample Rate: Any sample rate (44100 Hz, 48000 Hz, 96000 Hz, etc.). Because the Tracker stretches the waveform across your chosen envelope Duration or LFO Speed, the .wav header sample rate does not restrict playback speed.
5. Sample Length: Any length from 128 samples up to several seconds:
   • Single-cycle waveforms (128, 256, 512, 1024, or 2048 samples, such as Adventure Kid Waveforms (AKWF), Serum, or Vital single-cycle exports) work directly.
   • Drawn CV/envelope recordings of any length are automatically resampled across 128 evenly spaced points (0..127).

Step 4: Unipolar vs. Bipolar .wav Files (Automatic Detection)

Audio editors and synths export waveforms in one of two ways, and the Tracker automatically detects both:

• Unipolar Contours (All samples $\ge 0$, from 0.0 to +1.0):
  • Used by CV recorders and envelope generators.
  • Mapped directly: 0.0 = 0% modulation, +1.0 = 100% modulation.
• Standard Bipolar Audio Waveforms (Contains negative samples, from -1.0 to +1.0):
  • Used by standard audio editors and single-cycle synth wavetables.
  • Automatically shifted and normalized from [-1.0, +1.0] to [0.0, 1.0] (-1.0 $\rightarrow$ 0%, 0.0 $\rightarrow$ 50%, +1.0 $\rightarrow$ 100%) so negative halves of audio waveforms are never clipped or rectified.

Step 5: When Are User Wavetables Loaded?

• User wavetables from /Envelopes are loaded automatically from the SD card the first time a project uses or previews a U 001 – U 128 slot in a session.
• If you swap SD cards or add new files to /Envelopes, reboot the Tracker (or power-cycle) so the /Envelopes directory is rescanned cleanly.