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2011 was the year that Bluebrain, thanks to its much-buzzed album-app projects, became one of D.C.’s most notable musical exports, but you could say that everything started for the band with a more primitive technology: the boombox. In September 2009, the experimental pop group inaugurated its intriguing series of one-off musical experiments with “Cakeblood,” a 30-minute composition for about 50 boomboxes. For the performance, the duo of Ryan and Hays Holladay handed out cassettes (containing different parts of the larger composition) to boombox-wielding fans, and led a procession around Dupont. A second boombox walk—-featuring musical contributions from members of Beauty Pill, Animal Collective, and others—-followed in April 2010 on the National Mall.

Now, Bluebrain is bringing its boombox cycle to a close. On Saturday, Jan. 14 at 3 p.m., the group will lead a free boombox walk through the United States Botanic Garden. This time, they’re asking participants to RSVP via email and reserve a track. And the event isn’t boomboxes-only: If you want to bring a CD- or mp3-playing device with speakers, that’s cool.

The music, Ryan Holladay says, is still in the embryonic stages, although it’ll contain contributions from other musicians in some capacity. So why the early announcement? “The problem in the past has been finding working boomboxes,” he says. “so we decided to give people as much time as possible to prepare.”

“Cakeblood,” September 2009:

Cherry Blossom Boombox Walk, April 2010: