(1) File Format Restriction: Muro Box can only read single-track MIDI files and does not support other formats.

(2) Range Restriction:
N20: Range from C3 to A5, covering the white keys of a piano (excluding black keys).
N40: Range from F2 to A6, excluding F#2, G#2, A#2, and C#3.(Middle C = C3, 261.6 Hz)

(3) Track Length Restriction: Each song can be played for a maximum of 30 minutes as set in the app to prevent insufficient space on the mobile device.

(4)Playback Speed Limit:
At a tempo of BPM = 120, the minimum unit for consecutive single notes is an eighth note.
This means that when using eighth notes, the fastest possible rate for consecutive single notes is 4 beats per second, or 240 beats per minute.
Maximum simultaneous note output:
– N20 model = 7 notes
– N40 model = 10 notes
(Maximum simultaneous note output refers to the highest number of notes that can be struck and played at the same time.)

Q: Why is there a speed limit for note playback?

• Speed Limit: For the same pitch, the maximum playback rate is 4 beats per second (BPM = 240). Faster rhythms will be automatically filtered out.
• Design Rationale: Most music box melodies are gentle and soothing. Since the music box is a simple acoustic instrument, fast-paced arrangements require careful tuning to sound pleasant.
• Physical Constraints: Rapid consecutive notes can cause a “click” noise due to overlapping vibrations. To prevent this, a damper is needed to quickly stop the comb’s vibration.
However, due to the limited internal space of a music box, we cannot use large felt dampers like those found in pianos. Instead, we use a chrome-plated vibration absorber beneath the comb. While this performs better than traditional music boxes, it still doesn’t match the rapid damping effect of a piano.
• Motor Noise: Higher motor speeds increase gear and motor noise. Although the Muro Box motor can run faster, we’ve chosen the current setting to balance performance and sound quality.