Every musician knows the struggle: there is always that one difficult bar in a piece of music that trips you up. 🎶 You play it, make a mistake, stop, drag the progress bar back, and try again. It disrupts your flow and kills your momentum.
Effective practice isn't about playing the whole song from start to finish; it’s about isolating difficult sections and mastering them through repetition.
This is where MIDI Toolbox comes in. Our Online MIDI Player features a streamlined A/B Loop tool designed specifically to help you build muscle memory without taking your hands off your instrument. 🎸
Here is how you can use the A/B Loop function to transform your practice sessions.
Before we look at how to use it, let’s understand why it matters. Cognitive science suggests that "spaced repetition" is key to learning. By isolating a 4-bar phrase and playing it on an infinite loop, you allow your brain to:
We designed our loop tool to be intuitive so you can focus on playing, not clicking. Here is the step-by-step workflow:
Open the MIDI Toolbox Player in your desktop browser and drag and drop your MIDI file. Because our tool runs 100% locally, your file is processed instantly within your browser—no uploads, no waiting. ⚡

Play the track. Listen for the start of the difficult section you want to practice. Just as the music reaches that spot, click the Loop Icon [ ] in the control bar once.

Let the music play until the end of the phrase you want to practice. Click the Loop Icon [ ] a second time.

To exit the loop, simply click the icon again to toggle it off.
While listening is important, seeing the notes can dramatically speed up learning. MIDI Toolbox features a Vertical Piano Roll that scrolls downwards, similar to popular rhythm games or learning software like Synthesia.

When you have your A/B loop active, watch the notes falling:
For the best experience, we recommend using MIDI Toolbox on your laptop or desktop computer. 💻 Place your computer on your music stand or near your keyboard.
Since MIDI Toolbox supports Keyboard Shortcuts, you can control playback (Play/Pause) without fiddling with the mouse. This keeps your hands ready on the keys or strings, making your practice session much more efficient.
You don't need expensive software to practice effectively. With MIDI Toolbox, you get a privacy-friendly, zero-install solution that turns your browser into a powerful practice companion.
Ready to master that difficult solo?
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