MIDI Scale mapping: change notes, block classes and control Fold

Hear the changed notes, not just the scale name

The original MIDI melody here contains C, D, E, G and A, with a final C an octave above its opening. The C-minor mapping leaves C, D and G alone but turns E into E♭ and A into A♭. Play beyond the first two notes: they are unchanged, so judging only the opening would miss the effect.

Compare Bypass from the beginning using Rewind. With Scale active, the third note is MIDI 63 rather than 64, and the fifth is 68 rather than 69. The later E also becomes E♭. Eight notes still play with the same timing and velocity; the new colour comes from their pitches, not an audio filter or a volume change.

The named Minor map chooses a destination for every pitch class. In these editable preset maps, notes outside the scale are mapped downward to a scale tone, not necessarily to the nearest tone in either direction. Selecting a name loads those twelve decisions. It does not inspect the surrounding chord progression or distinguish an intentional chromatic passing note from a mistake.

Read one column at a time

Each grid column represents an input class relative to Base, and each row selects its destination. With Base at C, the E column’s E♭ row gives the change heard above. Click the diagonal E-to-E cell to restore the natural E while leaving A mapped to A♭. The named selection becomes Custom because the twelve-column map has changed.

Reset parameters restores this example’s Minor map and instrument. Base changes the pitch-class reference used to read the columns; it does not simply add that many semitones to every note. Keep Base at C while learning the grid, since its fixed column labels can otherwise be mistaken for absolute incoming note names. Transpose is the separate control for a uniform shift after mapping.

Rejection leaves a gap; redirection leaves a note

This second example starts from an otherwise identity map. Its D column is blocked using the bottom row, and its G column points to C. Fold is on. The first C still plays, the second input D is missing, and each G rises to the C above it. Seven events remain from the original eight.

Restore the D-to-D diagonal cell to bring the second note back. Then use Block D in the bottom row to remove it again. Blocking eliminates that event; mapping D to C would instead play C at the same point in the rhythm. Those are different compositional choices even when they both avoid the pitch D.

Fold chooses a nearby octave, not one shared register

Turn Fold off while leaving G mapped to C. The source G at MIDI 67 now becomes MIDI 60, seven semitones lower. Turn Fold on again: it becomes MIDI 72, five semitones higher. Listen to the change in melodic contour and check the transformed note row rather than expecting the whole phrase to collapse into a single octave.

The implemented rule adjusts the mapped pitch by octaves until it lies within six semitones of its input. It runs before Transpose. A subsequent +12 st Transpose therefore still raises the result an octave; Fold does not constrain the final output to a fixed keyboard region.

Keep the limits musical as well as numerical

Transpose spans −36 to +36 semitones, with final pitches clipped to MIDI 0–127. Redirecting several simultaneous inputs to one pitch does not guarantee independent sustained voices: overlapping same-pitch events can shorten each other in the output stream. A valid pitch-class result can still lose the movement or spacing that made the phrase work.

Unlike Pitch, this panel has no Lowest/Range input gate to adjust. Its stored range, if restricted elsewhere, leaves out-of-range notes unchanged rather than rejecting them; both examples cover the full MIDI range. Use the bottom-row blocks for explicit class rejection. Scale changes note pitches, not pitch-bend or slide expression into a guaranteed in-scale performance. Let the before-and-after events explain the rule, then let the melody decide whether that rule helps.