Roto-Control¶
Grainsmith Field ships a ready-made map for the Melbourne Instruments Roto-Control. It covers the full continuous parameter surface across the Roto's knob pages, plus four buttons for transport and performance. This applies to the standalone app; as an AUv3 plugin, MIDI comes from the host.
The quickest way in is the bundled Grainsmith.json. Import it into the Roto Control app and it sets up all 18 knobs in one step. The four buttons are not in the file, so you map those by hand from the table below.
The bundled profile¶
Grainsmith.json is a Roto-Setup import file. It defines 18 knobs across three pages, each on MIDI channel 1 in absolute 7-bit CC mode. Import it into the Roto Control app, then assign it to a slot on the unit.
The file contains knobs only. The Roto-Control export it was built from had no buttons mapped, so the four button actions are not written into the file. Map them by hand after importing (see Buttons below).
Knobs¶
All knobs on MIDI channel 1, absolute 7-bit CC. The pages below match the CC layout Field expects.
Page 1, CC 1 to 8:
| Knob | CC | Parameter |
|---|---|---|
| 1 | 1 | Size |
| 2 | 2 | Density |
| 3 | 3 | Jitter |
| 4 | 4 | Position |
| 5 | 5 | Reverb Mix |
| 6 | 6 | Reverb Space |
| 7 | 7 | Cutoff |
| 8 | 8 | Pitch Random |
Page 2, CC 9 to 16:
| Knob | CC | Parameter |
|---|---|---|
| 1 | 9 | Spread |
| 2 | 10 | Speed |
| 3 | 11 | Pitch |
| 4 | 12 | Morph |
| 5 | 13 | Reverse |
| 6 | 14 | Wet Mix |
| 7 | 15 | Scan Depth |
| 8 | 16 | Resonance |
Page 3, CC 17 to 18:
| Knob | CC | Parameter |
|---|---|---|
| 1 | 17 | Grain Shape |
| 2 | 18 | Level |
Set the encoders to absolute CC, 7-bit, range 0 to 127. Field reads these as absolute values. Relative mode or 14-bit hi-res mode makes the values jump or wrap.
Buttons¶
Assign four Page-1 buttons, all on MIDI channel 1, set to Momentary so they send 127 on press and 0 on release:
| Button | CC | Action |
|---|---|---|
| 1 | 40 | Play / Stop |
| 2 | 41 | Freeze (toggle) |
| 3 | 42 | Grain Shape (cycle Soft → Round → Sharp) |
| 4 | 43 | Record (toggle) |
The button CCs (40 to 43) sit clear of the knob CCs, so they never collide with a knob. Each button fires its action once on the press, when the value crosses from below 64 to 64 or above. Momentary is the intended mode; a latching button also works, since each press to 127 is a fresh trigger.
Grain Shape is reachable two ways. The Grain Shape knob (CC 17) sweeps across all three shapes, and Button 3 (CC 42) steps through them one at a time. Freeze lives on Button 2 as a toggle rather than on a knob.
Selecting the profile in Field¶
Field lists Roto-Control as one of the Controller Profiles in Settings (standalone only). Field merges all built-in controller maps into its live table, so the Roto's 17 parameter knobs and 4 buttons work whether or not Roto-Control is the selected profile.
Select Roto-Control as the profile to use the Level knob (CC 18). Level is recognized on the channel of the selected profile, so with a different profile selected the Roto's Level knob is not read as Level. The other knobs and the buttons are matched by their own channel and CC and are not affected.
Notes¶
- There is no push-reset. The Roto map defines no encoder-click channel, so pressing a knob does nothing in Field.
- Field echoes parameter changes back out on the mapped CCs, so the Roto's motorized knobs may track edits you make on screen. This is untested on hardware.