Sound / 05
Instruments
An instrument turns a Phrase note into sound or MIDI. GlassTracker supports SAMPLE, MACRO, external/hosted MIDI instruments, and reusable instrument files.
Opening an instrument
From a Phrase, put the cursor on an instrument value and use NAV+RIGHT. From Project, open Instrument Pool to browse all defined slots or create a new one.
The Phrase instrument column steps through free slot numbers as well as defined ones, so you can land on an unused slot and open it with NAV+RIGHT to create that instrument.
On the Instrument screen itself, the header is a single focus stop: left/right there select the previous and next instrument rather than moving between the two arrows. The Import/Export pair and the table/automation pair are also side-by-side rows, so left/right moves between the two controls in each.
Instrument types
| Type | What it does | Typical destination |
|---|---|---|
| NONE | An unused slot. | Reserve it or change the type before use. |
| SAMPLE | Loads a project-owned WAV into the engine and plays it chromatically or as slices. | Drums, loops, vocals, one-shots, single-cycle waveforms. |
| MIDI | Sends channel voice messages from the tracker to its selected destinations. | External hardware, another CoreMIDI app, AU Rack instruments, or MIDI-aware inserts. |
| MACRO | Runs the built-in Mutable Instruments Braids-based oscillator. | Synth voices generated directly by the tracker engine. |
Stop playback before changing an instrument type. If the slot contains meaningful settings, GlassTracker may ask for confirmation because the underlying engine object is replaced.
Instrument Pool
Project → Instrument Pool lists the project’s defined instruments. The list is alphabetized while preserving each instrument’s numeric slot. Select an item to open the engine-backed Instrument screen. Swipe a row left and tap the red Delete button to return that slot to NONE; this works in both the full pool and the iPad landscape instrument column.
In iPad landscape, select an instrument in INS and use EDIT for compact parameter controls that leave the composing screen in place. While Phrase is open, EDIT follows the effective instrument at the current step, including blank instrument cells that inherit from an earlier row. An explicit INS choice stays selected until you move the Phrase cursor. A SAMPLE instrument with an assigned WAV also shows Slices; it opens the full slicing workspace in the right pane without moving the tracker cursor. Done restores the same composing view.
- New Instrument chooses the next available slot.
- Instrument numbers in Phrases always refer to the stable project slot, not the list’s visual position.
- Name instruments early; the name appears in Phrase context and becomes the export filename.
SAMPLE instruments
| Parameter | Meaning |
|---|---|
| Sample | The project-owned WAV assigned to the instrument. |
| Volume | Instrument output level before the channel mix. |
| Pan | Stereo position; 7F/80 is approximately center. |
| Root Note | The note at which the sample plays at its original pitch. |
| Detune | Fine pitch offset around the root. |
| Crush Input / Bit Depth / Downsample | Lo-fi level, resolution, and sample-rate reduction controls. |
| Filter Cutoff / Resonance / Mix / Type | The sample instrument’s filter. |
| Start / Loop Start / Loop End | Playback and loop boundaries. The inline waveform keeps these spatial and touchable. |
| Slicing | Maps ordered sample regions to consecutive notes beginning at C-4 / MIDI note 48. |
| Automation / Table | Runs a reusable table continuously or one row per trigger. |
Assigning a sample
Use ASSIGN SAMPLE to choose from the Project Sample Pool. Use Browse / Import Samples to bring a source-library WAV into the project. Import creates a project-owned copy, so later edits cannot silently change the source library.
Inline waveform workspace
The sample instrument includes the same marker model used by the Sample Editor and Slices screen. Select Start, Loop Start, Loop End, a slice marker, or the parked playhead; audition with PLAY; use ENTER+arrows for sample-accurate movement.
With the workspace selected, NAV+RIGHT opens it full screen and sideways, where touch can also audition regions and add slices. See expanded workspace.
MIDI instruments
| Parameter | Meaning |
|---|---|
| Channel | Decimal MIDI channel 1–16. |
| Destination | ALL, MIDI OUT, AU RACK, or INSERTS. This decides which route classes receive the instrument; Channel then filters within them. |
| Volume | Startup MIDI CC 7 value (the tracker byte is scaled to MIDI 0–127). Note velocity starts at 127 and can be changed with VEL. |
| Program | Program Change sent at sequencer start; OFF disables it. |
| Length | Gate length in tracker ticks. 00 holds indefinitely until another note replaces it or transport stops. |
| Automation / Table | Runs MIDI-capable FX commands such as ARP, MCH, MCC, VEL, PSL/LEG, and program changes. |
An AU slot's LISTENS ON value matches this instrument channel. Duplicate listen assignments intentionally layer instruments. DELIVERS AS is separate: it changes the channel byte the matched plug-in receives and defaults to channel 1 for broad synth compatibility. See AU channel routing.
Create a normal MIDI instrument with destination AU RACK or ALL, then add an AUv3 synth and make its LISTENS ON channel match. The Phrase continues to use the MIDI instrument number, keeping projects compatible with the tracker engine.
MACRO
MACRO is the built-in Mutable Instruments Braids-based synthesizer. Its saved definition contains Shape, Timbre, Color, Attack, Decay, Signature, Volume, Table, Table Automation, and Name. Eight preallocated channel voices are shared by all MACRO definitions, so one definition can play independently on multiple tracks without creating DSP objects during Play.
MACRO implements VOL, ARP, PSL, PFT, KIL/GOF, and table playback. The MAC command changes Shape, Timbre, Color, Attack, Decay, or Signature on the running voice without modifying the saved instrument definition. It can be entered directly in a Phrase or used in a Table.
If a saved project contains an unknown instrument type, GlassTracker rejects it as invalid instead of interpreting it as a SAMPLE instrument.
Importing and exporting instruments
Instrument files let you reuse settings across projects.
- Give the instrument a unique descriptive name.
- Choose Export. GlassTracker writes the instrument under the app’s instrument library.
- In another slot or project, choose Import, select the exported
.ptifile, and press ENTER. ALT+PLAY remains an alternate import shortcut. - The imported definition replaces the current slot after confirmation.
Keep the associated samples backed up too. The instrument definition does not make an external source WAV portable by itself.
Resetting an instrument
Reset Instrument clears the slot’s current type/settings through the engine. It is destructive and may require confirmation. If the sample itself is used elsewhere, resetting the instrument does not directly delete the project-owned WAV.