How to Set Up MIDI Routing in Logic Pro

Last updated: March 2026

Logic Pro has a powerful MIDI system that handles everything from simple keyboard recording to complex multi-device routing with external synthesizers. This guide covers how to configure MIDI input, work with software instruments, connect external MIDI devices, use the IAC driver for cross-app routing, and troubleshoot the most common MIDI problems in Logic Pro on macOS.

Setting up MIDI input in Logic Pro

Logic Pro scans for connected MIDI devices at launch. To verify and configure MIDI input:

Software instrument tracks

Software instruments in Logic Pro receive MIDI and produce audio. To set up a software instrument track and play it with a controller:

1. Go to Track > New Software Instrument Track (or Cmd+Option+S)
2. The track is created with a default instrument. Click the instrument name to open the Library and choose a sound
3. Click the Record Enable button (the red circle) on the track header
4. Play your MIDI keyboard — you should hear the instrument respond

Logic uses a "last touched" model: whichever software instrument track you most recently clicked receives MIDI from your keyboard automatically, even without arming. This makes switching between instruments fast during composition.

Recording MIDI in Logic Pro

To capture a MIDI performance as a region:

1. Click the Record Enable button on the target software instrument track
2. Position the playhead where you want to start recording
3. Press R or click the red Record button in the transport bar
4. Play your performance — Logic records it as a MIDI region
5. Press Space to stop recording

Double-click the recorded MIDI region to open the Piano Roll editor, where you can edit individual notes, adjust timing, change velocities, and add or remove notes.

External MIDI instruments

To control a hardware synthesizer or external MIDI module from Logic Pro:

1. Go to Track > New External MIDI Track
2. In the track header, set the MIDI output port to your hardware device's MIDI input (via a USB MIDI interface or direct USB if the synth supports it)
3. Set the MIDI channel to match your synthesizer's receive channel
4. Play or record MIDI on this track — Logic sends the data to your hardware, and the synth produces sound
5. Connect the synth's audio output back to your Mac via an audio interface to hear it in Logic's mixer

MIDI FX: processing MIDI in the signal chain

Logic Pro includes a MIDI FX slot at the top of every software instrument channel strip. MIDI FX plugins process MIDI before it reaches the instrument. Built-in MIDI FX include:

• Arpeggiator: generates arpeggiated patterns from held chords
• Chord Trigger: expands single notes into chords
• Transposer: shifts all incoming notes by a set interval
• Velocity Processor: applies velocity curves, compression, or fixed velocities
• Scripter: JavaScript MIDI processor for custom logic

To add a MIDI FX: click the MIDI FX slot in the channel strip and select a plugin from the menu.

Using the IAC driver with Logic Pro

The IAC driver lets Logic send MIDI to other apps on the same Mac, or receive MIDI from them. First, enable the IAC driver in Audio MIDI Setup (see our IAC driver guide). Then:

To receive MIDI from another app in Logic: Create a software instrument track. Logic automatically sees IAC ports as MIDI input sources — they will appear in the MIDI In selection. Select the IAC port, and MIDI from the other app flows into Logic.

To send MIDI from Logic to another app: Create an External MIDI track. Set its MIDI Out to the IAC driver port. Play or trigger MIDI on that track — it sends to the IAC bus and any other app listening on that port will receive it.

Using Midilize with Logic Pro

Midilize works seamlessly as a MIDI preprocessor for Logic. Here is how to set it up:

1. In Midilize's Sources panel, create a virtual MIDI output port (e.g., "Midilize → Logic")
2. In Logic, this port automatically appears as a MIDI source for tracks
3. In Midilize's Flow Mode, connect your hardware controller through processing tools to this virtual output
4. Logic receives the processed MIDI from Midilize

This approach lets you apply transpose, velocity curves, channel filters, keyboard splits, and scripted transformations before MIDI reaches Logic — without adding any plugins to Logic's own channel strips. You can also use Midilize's Monitor Mode to inspect exactly what MIDI is flowing into Logic at any moment.

Troubleshooting MIDI in Logic Pro

No sound from a software instrument track: Check that the track's Record Enable button is on, or that the track is in MIDI monitoring mode. Verify the instrument plugin is loaded and not bypassed. Try playing the Virtual Keyboard (Window > Show Virtual Keyboard) — if the keyboard produces sound but your controller does not, the issue is with the MIDI input configuration.

External MIDI device not responding: Check the MIDI Out port selected on the External MIDI track. Verify the MIDI cable connects the interface's MIDI Out to the synthesizer's MIDI In (not the other way around). Try sending a MIDI note manually using the Virtual Keyboard on the external MIDI track.

MIDI notes sustaining after transport stops: Logic sends All Notes Off when the transport stops, but some synthesizers ignore this message. Use Midilize's Panic tool to send All Notes Off on all channels manually — or add a Panic button to your Logic session using the Scripter MIDI FX.

MIDI device not detected after connecting: Restart Logic Pro. The device was connected after Logic scanned for devices at launch. Verify the device appears in Audio MIDI Setup first.

Summing stacks for layered instruments

Logic Pro's Summing Stack is a powerful tool for layering multiple software instruments so they respond to MIDI from a single source. A summing stack works as follows:

1. Select two or more software instrument tracks that you want to layer
2. Go to Track > Create Track Stack and choose Summing Stack
3. Logic creates a folder track that combines the selected tracks
4. Playing the parent stack sends MIDI to all stacked instruments simultaneously

This is useful for layered pads, stacked piano sounds, or orchestral combinations where you want multiple instruments responding to the same performance. The stack's parent track controls volume, pan, and sends for the combined output of all child instruments.

For keyboard splits within a summing stack, use Logic's built-in Transposer or Scripter MIDI FX on individual child tracks to restrict each instrument to a specific note range. Alternatively, process the split upstream in Midilize and route each split range to a different IAC bus, then create separate tracks in Logic for each bus.

Piano Roll and MIDI editing

Once you have recorded MIDI in Logic, the Piano Roll provides full editing capability. Double-click any MIDI region to open it. In the Piano Roll you can:

• Move notes by dragging them horizontally (time) or vertically (pitch)
• Resize notes by dragging their right edge to change duration
• Edit velocity by clicking the velocity bars at the bottom of the Piano Roll
• Quantize timing using the Quantize menu (Q) to snap notes to a rhythmic grid
• Select all notes on a specific pitch by clicking the piano key on the left edge
• Use the Brush tool to draw new notes directly on the grid

Logic's Piano Roll also shows CC automation lanes when you click the disclosure triangle at the bottom. Recorded CC messages from your controller — mod wheel, expression pedal, pitch bend — appear as automation curves that you can edit with the same tools as notes. This allows post-recording refinement of controller movements that were captured during a live performance.

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