Drop balls with millisecond precision

The Road to the Perfect Marble Dropper

[Martin] of the band [Wintergatan] is on his third quest to build the ultimate musical marble machine, and it means dropping balls with maximum reliability and precision timing. Working through several iterations and going back to first principles, he designed a marble gate that can drop marbles with a timing standard deviation of 0ms.

[Wintergatan]'s first two machines, Marble Machine and Marble Machine X, attracted attention, but their complexity caused their downfall. It turns out that a Rube Goldberg machine making music has a lot of potential points of failure, and both machines proved too temperamental for the live stage. The third version, Marble Machine XT (T for "touring") had to be redesigned to be simple and reliable to be practical on the road.

[Martin] has broken down the concept of the marble machine into its key components, of which the marble door is the most obvious. By using a pair of contact microphones to record the moment of release and impact, it can accurately measure timing. The first design had a standard deviation of 3.91ms, which isn't good enough for us to detect by ear, but isn't up to [Martin's] standard for "music tight". It used a clock-like escapement mechanism, where the wheel is the release gate. After reviewing his measurement software and compensating for drift between software components in his setup, the measured standard deviation was reduced by 1 ms. Another breakthrough was to remove all guiding surfaces under the door and let gravity do all the work. The 8th iteration turned out to be the winner and used the escape arm as a drop gate and wheel to hold back the line of marbles.

Coming from an artistic background, [Martin] had to learn many engineering lessons the hard way. Watching the videos on his YouTube channel, it looks like he's taking the lessons to heart, and we can't wait to see the Marble Machine XT come to life.