Manual

ChordPad Builder lets you build chord progressions on a 128-pad grid like on the MPC, listen to them, send them to your MPC via MIDI and export them as .progression files for the MPC.

1. Quick start

1. Choose Root and Scale at the top, e.g. C and minor.
2. Type a progression into the quick entry below the pads, e.g. Cm7 Fm9 A#7 D#maj7 or as degrees i7 iv9 bVII7 bIIImaj7, and press Enter.
3. Click the pads or press Z X C V to hear the chords.
4. Try inversions and variants in the editor on the right.
5. Use Export to save a .progression file and load it on your MPC.

2. Browser & requirements

The app runs entirely in the browser – nothing to install.

Google Chrome is recommended. Other browsers show a notice at the top explaining what doesn’t work there. Pads, generator, browser sound and import/export via download work everywhere.

3. Pads & banks

Like on the MPC there are 8 banks (A–H) with 16 pads each – 128 pads in total. Pad 1 is bottom left, pad 16 top right.

• Click and hold plays the chord as long as you hold and selects the pad for the editor.
• Drag a pad onto another to swap them, hold ⌥ to copy.
• Each pad shows its number, chord name, degree in the selected key (e.g. ii7) and the notes.
• Color: “Root” colors by root along the circle of fifths, “Function” by harmonic role – tonic blue, subdominant green, dominant orange, borrowed purple, secondary dominant red.
• ▶ Bank plays all programmed pads of the bank in order – tempo (BPM) and beats per chord are adjustable, optionally as a loop.
• Clear pads … clears the current bank or all pads, optionally also name and key.

4. Entering chords

Chord names

Common spellings are understood, for example:

C  Cm  C7  Cmaj7  Cm7  Cdim  Cdim7  Cm7b5  Caug  Csus2  Csus4  C5
C6  Cm6  C69  Cadd9  Cmadd9  C9  Cmaj9  Cm9  C11  Cm11  C13
C7b9  C7#9  C7b13  C7#11  C7#5  Cmmaj7  C/E  Dm7/G  Bb7  F#m9

min, -, M7, Δ, ø, ° and (add9) work too.

Degrees (Roman numerals)

Instead of chord names you can type degrees of the current key: upper case = major, lower case = minor, plus b/# for alterations. Examples: ii7 V7 Imaj7, i bVI bIII bVII, iiø V7 i.

Ways to enter

• Editor field “Type a chord” + Enter fills the selected pad. With “→ next pad” the selection moves on. A trailing number sets the octave, e.g. Cm 2.
• Quick entry below the pads: several chords at once, starting at the selected pad.
• Chords in the key: the editor lists all diatonic triads and seventh chords to click.
• Keyboard: click notes to add them to or remove them from the pad; the name is detected automatically.
• MIDI recording: play a chord on your MIDI keyboard or the MPC (see MIDI).

Voice leading & bass note

With Voice leading the app picks the inversion of each new chord that sits closest to the previous pad – that sounds much smoother than root positions only. Bass note adds the root one octave lower.

5. Editor: voicings & variants

• Voicing: inversion up/down, octave ±, Close (all notes within one octave), Drop 2 / Drop 3 (second- or third-highest note one octave lower – classic jazz voicings), Wide, add/remove bass.
• Inversions: all inversions of the chord as buttons; the active one is highlighted.
• Variants: extensions on the same root, e.g. C → Cmaj7, C6, Cadd9, Cmaj9, C69, Csus2.
• Substitutions: relative, mediant, tritone substitution, ii-V, chromatic mediant and more – each with its degree in the current key.
• Name: with “auto” the name is detected from the notes; untick it to use your own names.
• Copy, paste, duplicate (into the next free pad) and clear pad.

Every change can be undone with ⌘Z.

6. Keyboard & scales

The keyboard shows the selected pad: chord tones red/blue, the root orange, scale tones with a green dot.

• Show scale → Key: the scale of the key set at the top.
• Show scale → Chord scale: the matching scale for the chord, e.g. D Dorian over Dm7 in C major or G Mixolydian over G7 – great for finding melodies and solos.
• ◀ ▶ moves the visible octave range.
• ⇧-click only plays a note without changing the pad.

Octaves are counted the Akai way: C3 = MIDI note 60.

7. Genre generator

About 60 genres in groups: Pop/Rock, R&B/Soul/Funk, Jazz/Blues, Hip-Hop/Lo-Fi, Electronic, Reggae/Caribbean, Latin, Folk/World and Cinematic/Classical.

1. Choose genre, root and mode (auto, major or minor).
2. Length: original, 4 or 8 chords.
3. Color: left = plain (triads), right = richer with sevenths, ninths, borrowed chords, secondary dominants and tritone substitutions.
4. Suggest progressions delivers five new variations – every click gives different ones.
5. Click single chord chips to listen, ▶ Listen for the whole progression, ★ for favorites.
6. To pads from … places the progression starting at the selected pad. If the pads are empty, the key and a matching name are applied.

8. Library & sets

• Bundled: ready-made progressions to listen to and load.
• Folder: open a folder with .progression files (Chrome/Edge only). Files are grouped by category, searchable, playable and loadable. The folder is remembered.
  • MPC software on the Mac: press ⌘⇧G in the folder dialog and enter /Library/Application Support/Akai/MPC 3/Progressions.
  • MPC hardware: connect the MPC in computer mode and choose the Progressions folder on its drive.
• My sets: stores all 128 pads including name and key under a name – e.g. one per song. Sets can be exported as a file and imported again.

When loading into pads that aren’t empty, the app asks: replace bank, replace everything, insert from the selected pad, or fill empty pads only.

9. Analysis

The Analysis tab detects the most likely key of your pads (top 3 to apply) and shows for each chord its degree, function (diatonic, borrowed, secondary dominant, tritone substitute, chromatic) and matching scale. Below you can type any chord progression and analyze it. At the top right a chip always shows the detected key – click it to apply.

10. Import & export

Import

Use Import (⌘O) or simply drag one or more .progression files into the window.

Export

• Scope: the current bank only, or all banks A–H in pad order.
• Name: the MPC groups by the part before the first hyphen – RnB-Late Night appears as “Late Night” in the category “RnB”. The dialog shows the split live.
• Gaps: empty entries crash the MPC software. If there are empty pads before the last chord, choose between Compact and Keep positions (gaps are filled with copies of your chords one octave higher).
• Saving: download, “Save as …” or directly into the folder from the library.

File format

The export matches the MPC factory files exactly – importing and re-exporting a factory file produces an identical file.

{
    "progression": {
        "name": "Category-Name",
        "rootNote": "C",
        "scale": "Natural Minor",
        "recordingOctave": 2,
        "chords": [
            { "name": "Cm7", "role": "Root",   "notes": [48, 51, 55, 58] },
            { "name": "Fm9", "role": "Normal", "notes": [53, 56, 60, 63, 67] }
        ]
    }
}

11. MIDI

The app can send chords via MIDI to your MPC or other devices and receive them from a MIDI keyboard. The first time, Chrome asks for permission to use MIDI devices – please allow it.

MPC directly via USB (standalone)

1. Connect the MPC to the computer via USB. It shows up with three ports, e.g. “MPC Live III Port 1/2/3”.
2. In the app choose “Port 1” as MIDI out (the app selects it automatically if nothing is set yet).
3. On the MPC:
   • select a keygroup or plugin track (e.g. a piano or pad) – a drum program plays single pads instead of chords,
   • set the track’s MIDI input to “All” or “USB”,
   • use the same channel as the app (default 1) or “All”,
   • set monitoring to “Auto” or “On” and select the track.
4. Click Test in the app – the MPC should play a C major chord.

MPC software on the Mac (via the IAC driver)

A browser can’t create its own virtual MIDI port. On the Mac, the built-in IAC driver does that job:

1. Open Audio MIDI Setup (Applications → Utilities).
2. Window → Show MIDI Studio, then double-click IAC Driver.
3. Tick “Device is online” and apply.
4. In the app choose “IAC Driver Bus 1” as MIDI out.
5. In the MPC software enable the IAC bus as an input under Preferences → MIDI and select it as the track’s MIDI input.

On Windows a tool like loopMIDI does the same.

Record to pad (MIDI in)

1. Choose your keyboard or “MPC … Port 1” as MIDI in at the top.
2. Tick “Record to pad” and select a pad.
3. Play a chord – as soon as all keys are released it lands in the pad, the name is detected and the selection moves to the next pad.

Played notes appear live on the keyboard; with Browser sound enabled you also hear them in the browser.

More MIDI settings

• Channel: MIDI channel 1–16 for all notes sent.
• Vel.: velocity of the notes sent.
• Browser sound: built-in electric piano sound for listening without a DAW – can be used alongside MIDI or switched off.
• Test: sends a C major chord to the selected MIDI out.
• Panic (Esc): emergency stop for stuck notes – stops playback, sends note-off for all sounding notes plus “All Notes Off” (controller 123). This happens automatically when you change port or channel.
• The status LED shows whether a MIDI out is connected; it blinks while sending.

12. Keyboard shortcuts

On Windows use Ctrl instead of ⌘.

13. Your data

Everything is saved automatically and only in your browser – pads, settings, favorites and sets. There is no account and no upload. That also means clearing browser data, or using another browser or computer, starts with empty pads. Back up important work as a .progression file or via “My sets → Export all sets”. Details are in the privacy policy.

14. Troubleshooting

The MPC doesn’t play anything

• Is “Port 1” selected as MIDI out (not 2 or 3)?
• Is a keygroup or plugin track active on the MPC, with MIDI input “All”/“USB” and the matching channel?
• Did Chrome get MIDI permission? Check via the lock icon in the address bar → site settings → MIDI devices.
• Was the MPC connected after opening the page? The list updates automatically – reload the page if needed.

A note is stuck

Click Panic or press Esc.

The MPC plays single notes or drums instead of chords

A drum program is active on the MPC – select a keygroup or plugin track instead.

Saving to the MPC folder fails

The factory folder is read-only (see Export). Choose your own folder.

Import reports an error

Only valid .progression files (JSON with progression.chords) are read. Empty chord entries are skipped on import.