In GarageBand for Mac, select the MIDI notes in the Piano Roll Editor and drag the Velocity slider right. Apple documents that their velocity differences are preserved until one selected note reaches 127. Leave Option released to retain that relationship.

This walkthrough is for editing an existing MIDI passage on a Mac. It explains how to choose the notes, calculate the available increase, and verify the result using a neutral four-note example. The procedure and its boundary come from Apple’s documentation for editing notes in the Piano Roll Editor.

Open the MIDI region and select the notes you want to change

Start with a MIDI region on a software instrument track. Double-click the region to open the Piano Roll Editor beneath the tracks. Alternatively, select the region and choose View > Show Editor. Apple describes both methods in Intro to the Piano Roll Editor in GarageBand on Mac.

Make the editor large enough to select your passage accurately. You can drag its upper divider upward to increase its height. The inspector sits to the left of the note area; when individual notes are selected, its Notes controls include the Velocity slider. These layout details are documented in Apple’s Piano Roll Editor introduction.

Choose the intended notes before touching the slider:

  1. Click a note to select it individually.
  2. Use Shift-click to select additional notes, or drag a selection rectangle around the passage.
  3. Check that the selection contains every note you intend to raise and excludes notes you want to leave alone.

Apple documents these selection methods in Edit notes in the Piano Roll Editor in GarageBand on Mac.

Treat selection as part of the edit. For example, if your task is to raise four notes in the middle of a region, select those four rather than a larger surrounding passage. The maximum velocity within that selection determines how much room the group has for an increase.

Raise the selected velocities while retaining their spacing

With the notes selected, drag the Velocity slider right without holding Option. Apple states that editing several notes together retains the differences between their velocity values. The inspector and the horizontal lines inside the notes update during the adjustment. See Apple’s velocity-editing instructions.

For an exact editing task, define “relative differences” as the numerical gaps between velocities. If two notes start at 52 and 68, their gap is 16. Adding 18 to each produces 70 and 86, which still differ by 16. This preserves the spacing of the values; it does not preserve their ratio or apply the same percentage increase.

That distinction helps you choose a clear target. “Raise every selected note by 18” describes a common offset. “Make every note 25 percent stronger” describes a different calculation. The supported workflow here uses the first meaning: raise the group while keeping its existing velocity gaps.

A worked four-note example

The following values are synthetic arithmetic examples, not measurements from a GarageBand session. Imagine four successive notes with velocities of 52, 68, 83, and 101. You want to raise each by 18.

Note Starting velocity Intended increase Resulting velocity
A 52 18 70
B 68 18 86
C 83 18 101
D 101 18 119

The gaps between successive notes remain 16, 15, and 18. All four notes have moved upward by the same amount, so the original pattern of lower and higher velocities remains intact.

Before editing, write down the starting values if exact results matter. After adjusting the group, inspect notes individually and compare the results with your targets. For this example, the check is simple: each resulting value should be 18 above its starting value. This is a verification method derived from the arithmetic, rather than an additional GarageBand command.

Calculate how far the group can rise before it stops

Apple documents a MIDI velocity range of 0–127 in GarageBand. During an ordinary group velocity adjustment, reaching either endpoint with any selected note prevents further adjustment of the group. For an upward edit, the relevant endpoint is 127. Apple also documents an Option override, which changes the velocity relationships. See Edit notes in the Piano Roll Editor in GarageBand on Mac.

You can therefore calculate the largest possible increase that preserves every selected note’s numerical differences:

Maximum common increase = 127 − highest selected velocity

In the four-note example, the highest starting velocity is 101. Subtracting it from 127 leaves 26. A common increase of 18 fits, and an increase of 26 reaches the boundary exactly.

Note Starting velocity After adding 26
A 52 78
B 68 94
C 83 109
D 101 127

An increase of 30 would instead require values of 82, 98, 113, and 131. The last value exceeds the documented maximum. Consequently, no result within the available range can give all four notes that increase while preserving their original differences.

This calculation also explains why a selection can seem to have very little adjustment available. A single selected note at 124 leaves room for only three additional velocity units across the group. A selected note already at 127 leaves no upward room. These are consequences of Apple’s documented group-editing boundary.

Why the Option override does not meet this task

Apple allows you to hold Option while dragging to continue changing velocity values beyond the ordinary group stop. It explicitly states that overriding changes the velocity relationship between notes. Use the normal drag when preserving those relationships is your requirement. The modifier is not a way to fit an otherwise impossible common increase inside the same range. Apple’s documented override behavior.

If your intended increase is too large, choose a smaller common offset. Editing only a subset creates a different task: you may preserve the differences within that subset, but its relationships to the excluded notes will change.

Check the numerical result and the sound separately

After the adjustment, compare the individual values with your recorded starting values. For a strict common-offset edit, every note should have the same increase. Checking only which note remains highest is insufficient: the ordering could stay the same even if the gaps changed.

Then play the passage with the same instrument settings. Apple explains that velocity usually relates to loudness, but it can also affect synthesizer parameters such as filter cutoff or resonance. Preserving numerical velocity gaps therefore does not establish an identical perceived loudness gap between notes. Apple’s explanation of note velocity.

If the latest adjustment is unsuitable, choose Edit > Undo or press Command-Z. Apple documents this as the way to reverse the last edit operation in Undo and redo edits in GarageBand on Mac. Return to your original values before trying a different offset so that each comparison has a clear starting point.

When track volume is the more useful control

If your practical goal is simply to make the track louder in the mix, consider its volume control. Apple documents that dragging the track header’s Volume slider right raises the track level. You may need to widen the track header to see it. See Set track volume levels in GarageBand on Mac.

Track volume offers a supported path to a higher playback level when the note velocities have no remaining upward room. It does not fulfill a requirement to increase the MIDI velocity numbers themselves. Choose velocity editing when you need to change the note values and hear the instrument’s response to them; choose track volume when the task is adjusting the track’s level within the project.

For the exact MIDI editing outcome, select the intended notes, calculate the room below 127, and make an ordinary group adjustment with Option released. Verify the common increase afterward. When the highest note reaches the endpoint, reducing the requested increase is the way to keep every original velocity difference intact.

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