Though deserving of other, more flattering titles, “Signal Morning” will go down as 2009’s unlikeliest record. Its story begins in 2000 with the breakup of psych-pop revivalists The Olivia Tremor Control, who, throughout the 90s, had—along with The Apples in Stereo and Neutral Milk Hotel—served as a pillar of the Elephant Six Recording Co., a sprawling collective of indie rock bands based in Athens, Ga. With two of that decade’s finest albums—1996’s “Dusk at Cubist Castle” and 1999’s “Black Foliage”—under their belt, co-songwriters Will Cullen Hart and Bill Doss parted ways. Doss went on to pursue solo projects under the moniker The Sunshine Fix, while Hart and the remaining members of OTC reformed as Circulatory System, and released their self-titled debut in 2001.

That was eight years ago, and until relatively recently, news from the Circulatory System camp, with the exceptions of a few Athens shows and a brief OTC reunion tour, was frustratingly rare. Around 2005, blogs and message boards buzzed over rumors of a new album—tentatively titled “Blasting Through”—to no avail, and years went by until even the most eager fans reverted to a doubting Thomas mentality. By 2007, it seemed basically impossible that “Blasting Through” would ever see a proper release—more likely its demos would be found decades later in a rented attic, as Elephant 6 projects are wont to do.

Finally, in late 2008, Hart revealed a primary reason for the seemingly endless delay: he had been diagnosed with Multiple Sclerosis, a sobering reality for fans of the painter (who’s designed all his own album art) and musician. But while some might expect Hart’s disclosure to be a farewell message, it instead marked Circulatory System’s revival: recorded in seven studios over almost eight years, the band’s sophomore album—now optimistically-titled “Signal Morning”—would finally see the light of day.

To put it mildly, the album does not disappoint. “Signal Morning” overflows with too many ideas and sounds, even after numerous listens, to possibly cite. It is an astounding collection of lushly-layered pop nuggets delivered with gestalt-like intensity; take “Overjoyed,” Side One’s most boisterous track, as an example. A few seconds of warbling static and electronic beeps lead into a chorus of cellos, each emitting a unique, somber strain. Abruptly, the strings are silenced, giving way to a pounding fuzz-bass line and Hart’s abstract yet compelling musings: “Soon you’ll know that we’ve been here before / and you will know we’ve found this world because everyone is overjoyed,” Hart proclaims, “and everything that you say is magic.” The cellos return as the bass fades into the background, and the melody gives way to an onslaught of feedback and ominous marching drums. The song ends with a few seconds of rapid blasts of static, alternating between the left and right channels. In a mere two and a half minutes, Hart has managed to showcase his labyrinthine inventiveness at its finest.

The theme of frenetic propulsion that subsists throughout “Signal Morning” is the album’s most distinct improvement over its predecessor, and its strongest link to Hart’s work with his former band. Where Circulatory System’s melancholic debut was widely praised initially, the album hasn’t aged as well as its OTC counterparts, due to the understandable but largely overblown criticism that the album lacks stylistic variety and lapses too easily into a monotone. Though “Signal Morning” retains many of that album’s lyrical themes, (circular time, nature, nostalgia, and otherworldly transcendence) it’s a closer sonic companion to Hart’s work on “Black Foliage.” This should come as no surprise, since all former OTC members, including Bill Doss, play on “Signal Morning.”

“Signal Morning” posits the intricate juxtapositions of 60s pop and ambient noodling of “Black Foliage,” condensed into a frenzied dreamscape, with the volume cranked way up. “Overjoyed” and opener “Woodpecker Greeting Worker Ant”—among others—are some of the loudest, most vibrant songs that Hart has ever released. “Round Again,” the album’s centerpiece and a top contender for its catchiest song, layers guitars and bass over a wall of fuzz and relentless drumming by Jeff Mangum (OTC’s original drummer, later of Neutral Milk Hotel fame). Hart’s vocals, sedate throughout most of his tenure with Circulatory System, suddenly take center stage. “Do you think we can lift this shadow?” he asks, following this question with urgent repetition—“Do you think? Do you think? Do you think?”—until he ends the line with a tinge of bitterness: “Do you think at all?” As a vocal performer, Hart has never sounded more immediate and direct.

On the album’s title track, and closing song, majestic piano chords ascend over a din of jangling guitars and trumpet bleats, providing a fitting segue into the eerie coda of this whirlwind record. It proves a satisfying conclusion to this chapter in William Cullen Hart’s life and Circulatory System’s existence. But even without the album’s context—the fans’ long wait, the band’s logistical struggles, and Hart’s unfortunate illness—“Signal Morning” would still stand as a masterpiece of modern pop music, and another fascinating testament to one of its greatest minds.

—Staff writer Jeffrey W. Feldman can be reached at jfeldman@fas.harvard.edu.