MIDI note preview silent after changing clock source?

You changed a MIDI clock source and now the note preview is silent, late, or unreliable. Clock sync and note output are related in some music setups, but they are different signals, so changing the clock source does not necessarily stop notes from reaching an instrument.

First check whether your keyboard sends notes at all. The MIDI Test can show incoming key messages. It does not play a sound or test a DAW's MIDI output, so use it to identify which part of the route needs attention.

Check the note path

1. Open the MIDI Test in a browser other than Safari. MIDI Test does not work in Safari.
2. Connect your MIDI keyboard or controller and allow MIDI access if the browser asks for permission.
3. Press and release one key. Look for a message showing that a note was pressed, followed by a release message when you let go.
4. Try a few keys across the keyboard, including one that you know should trigger the instrument or preview in your music app.
5. If the test receives key messages, return to your music app and check its selected MIDI input, instrument, and audio output. If it receives nothing, check the connection and selected device first.

The browser test listens for incoming MIDI from the controller. It cannot confirm that a DAW is sending MIDI to an external synthesizer, or that an instrument plugin is producing sound.

What the result means

Key messages appear in MIDI Test

The controller is sending notes to the browser. If the same keyboard produces no preview in your music app, the likely issue is after the physical keys: the app may have the wrong input selected, the track may not be armed or routed, or the instrument may not be loaded. Check the app's MIDI input and instrument settings.

No key messages appear

The browser is not receiving notes from that controller. Check that the keyboard is powered, connected, and selected if the test offers a device choice. Try another USB port or reconnect Bluetooth. A clock-source setting alone usually does not explain missing key messages from a keyboard.

Notes appear, but the instrument remains silent

MIDI messages contain instructions such as which note to play. They are not sound. The instrument or synth must receive the message and create audio, and that audio must reach the selected speakers or headphones. Check the track or instrument's MIDI routing, then check the audio output.

The preview works, but timing or playback is wrong

The note path and audio output may be working while clock sync is not. A MIDI clock source determines which device or app sets the beat and tempo. A sequencer or plugin that follows external clock can pause, run at the wrong tempo, or wait for a clock even though individual notes still arrive.

How to fix it

1. Check the clock source and transport. In your music app or keyboard, confirm that the intended device is set as the clock source. If the instrument is waiting for external clock, start the master device or select the app's internal clock for a basic test. The exact setting name varies by device.
2. Select the correct MIDI input. In the music app, choose the connected keyboard or controller as the track or instrument's input. If several devices have similar names, disconnect the others briefly and check which name disappears.
3. Check the instrument and track routing. Make sure the track is assigned to a playable instrument, is receiving the relevant MIDI channel, and is not muted. If live input needs a record-enable or input-monitor setting, turn it on for the test.
4. Check the audio output. On Windows 11, open Settings › System › Sound and select the intended device under Output. On macOS, open System Settings › Sound › Output and choose your speakers, headphones, or audio interface. Then check the music app's own output selection and volume.
5. Test the computer's sound separately. Open the Speaker Test and play a tone at a low level. If you hear the test tone but not the instrument, focus on the music app and its routing. If you hear neither, investigate the system output, cable, or headphones.
6. Reconnect and restart in a simple order. Close the music app, reconnect the controller and audio interface, then reopen the app and select the devices again. If the issue remains, restart the computer to clear a stuck connection.

Why changing MIDI clock can affect a preview

MIDI clock is a stream of timing pulses used to keep sequencers and tempo-based effects in sync. Note messages tell an instrument which key to play and when to start or stop it. A clock change can therefore affect a preview that depends on a running sequencer, arpeggiator, or tempo-synced instrument, without stopping ordinary note input.

Some keyboards also have local sounds, where pressing a key plays the keyboard's own tone, and external sounds, where the keyboard sends notes to a computer or another instrument. A browser MIDI test checks the messages arriving from the controller, not the keyboard's built-in audio or a device's MIDI output.

Use the MIDI Test to confirm incoming key messages, then use your music app's routing and clock controls to check the rest of the path. The test does not record or upload the notes you play.