In the spring of 1999, Charles Curtis, Alan Licht, and Dean Roberts brought an unconventional mix of drone, improvisation, and experimental rock on an eleven-stop tour of Europe. The concept was straightforward, yet novel: each night, they would improvise a single piece while sustained sine waves played for the duration of the concert. May 99, culled from three shorter pieces recorded for a radio program at Amsterdam’s VPRO near the end of the tour, represents an early high watermark in the collision of minimal and rock sensibilities that started to become prevalent in the late 90s and is an ear-opening listen even for those familiar with the musicians’ other projects. May 99 combines resonant sine waves in the style of eminent downtown New York composer La Monte Young’s Theater of Eternal Music with scratchings, scrapings, and warblings produced by Licht and Roberts’s guitars, Curtis’s cello, and a variety of electronics. Just as sine waves hold together these sundry improvisations, a shared tendency toward the minimalistic—Licht’s performances with the Blue Humans, collaborations with Loren Connors, and solo guitar records; Roberts in the band Thela and his solo project White Winged Moth; and Curtis performing with Young and his own Trio—brought together three musicians with very different backgrounds, creating fertile ground on which they generated the album’s unclassifiable sounds.