Check MIDI velocity after switching USB interfaces

After switching USB interfaces, your keyboard may still play notes while a music app responds differently to how hard you press the keys. The sound alone cannot tell you whether the keyboard is sending different MIDI velocity values or the instrument software is interpreting them differently.

Use the MIDI Test to check the notes and velocity values arriving in your browser. Compare the same key presses before and after the change, then narrow down whether the keyboard, interface, connection, or software setting is responsible.

Check note-on velocity

1. Open the MIDI Test in Chrome or Edge on your computer. MIDI Test does not work in Safari.
2. Connect the keyboard through the USB interface you want to check. If the browser asks for MIDI access, allow it. If the test lists more than one MIDI input, choose the keyboard or interface input you are testing.
3. Press one key softly, then at a medium force, then firmly. Repeat the same three presses on that key several times, and watch the incoming MIDI messages and velocity values.
4. Switch to the other USB connection or interface and repeat the same presses on the same key. Keep the keyboard's settings and the way you press the key as consistent as you can.

If you are diagnosing a change, compare the same keyboard, key, and playing technique. Testing a different key or a different keyboard can make the results harder to compare. If possible, note down a few values for soft, medium, and firm presses on each connection.

What the result means

Velocity rises when you press harder on both connections

The keyboard is sending varying velocity values through both paths. A small difference between individual presses is normal because it is difficult to repeat the exact same force. Look for a consistent change, not one slightly different reading. If the values are similar but the sound changed, check the instrument's velocity response, volume, and dynamics settings in the music app.

Values are lower or higher through one interface

The MIDI path or a keyboard setting may be changing the data. Some keyboards offer a velocity curve or a fixed-velocity mode, which can make values lower, higher, or more uniform. A basic MIDI interface usually passes note data through, but a device or software setting can filter or transform it. Check the keyboard settings and test the interface with another USB port or computer.

Every press shows nearly the same value

The keyboard may be set to fixed velocity, or its velocity response may be too limited to distinguish your presses. Check for a setting named Fixed Velocity, Touch, or Velocity Curve in the keyboard's own controls or manual. If only one connection produces uniform values, check for a setting or processing feature associated with that connection.

No notes or velocity values appear

The browser is not receiving MIDI input. The wrong input may be selected, the browser may not have permission, or the keyboard and interface may not be connected or recognized. This does not by itself prove that the keyboard is broken. Work through the fixes below.

Notes appear, but velocity is zero or a note seems to stop immediately

In MIDI, a Note On message with velocity zero is commonly treated as a Note Off. It can therefore represent a note ending, not a key press with no force. Check the sequence of messages and whether a normal Note On with a nonzero velocity arrives when you press the key.

How to fix it

1. Check the keyboard's velocity setting. Turn off fixed velocity and choose a normal touch or velocity curve. The wording and location vary by keyboard, so check its menu or manual. Repeat the same soft, medium, and firm presses after changing it.
2. Check the connection path. Reseat the USB cable and try another port on the computer. If you are using a hub or dock, connect the interface directly to the computer for a test. Avoid changing cables and settings at the same time, so you can identify what made a difference.
3. Allow MIDI access in the browser. If you previously blocked access, open the site permission controls beside the address bar, allow MIDI access if the option is shown, and reload the page. Browser controls vary. If the site does not offer a MIDI permission there, try opening the test again and respond to its access prompt.
4. Check that the computer sees the interface. On Windows 11, open Device Manager from Start and look for the connected device, especially any warning symbol. On macOS, open Applications › Utilities › Audio MIDI Setup, then choose Window › Show MIDI Studio. These screens can help show whether the system recognizes a device, but they do not measure key velocity.
5. Test without other MIDI software open. Close music apps and other browser tabs that may be using the device, then reconnect it and try the test again. If your keyboard uses manufacturer software, check that it is not applying a velocity curve or filtering messages.
6. Try the other interface or another computer. Keep the keyboard and cable the same where possible. If the problem follows one interface across ports or computers, check for its driver or firmware update from its manufacturer, or ask the seller about repair or replacement.

Windows 11 and macOS sound settings control audio input and output, not the MIDI velocity a key sends. Raising microphone volume or speaker volume will not change a note-on velocity value.

When the interface or keyboard may be faulty

A single browser test cannot identify which component is defective. To isolate the cause, compare the keyboard through its direct USB connection, if available, and through the interface. Then test the interface with another MIDI device, or test the keyboard on another computer. If one interface consistently drops notes or changes the messages while the other connection works, the interface, its cable, or its driver is the likely cause. If the same keys fail through every connection, the keyboard may need service.

Velocity measures how the keyboard reports a key press, not the exact physical force in pounds or newtons. The MIDI Test reads messages in the browser, so it cannot confirm what a particular music app does with those values. MIDI access is requested by the browser, and the test does not need to record audio.