The greatest jazz musicians are revered. A few of the greatest jazz musicians are beloved. Gil Evans was beloved, and not just for his masterpieces, like Out of the Cool and Sketches of Spain. Almost any Evans arrangement explores emotions that listeners had once assumed were unique to themselves. For many people, Evans is personal. The elusive beauty of his arrangements hints at what life might have been.

So when rumors of a project containing previously unrecorded Evans music begin circulating, they create a lot of buzz. The rumors are true, and the album is Centennial: Newly Discovered Works of Gil Evans, by Ryan Truesdell, on ArtistShare. Its release date of May 13, 2012, is the 100th anniversary of Evans’ birth. (He died in 1988 at 75.)

Truesdell is a 32-year-old composer, arranger, producer and copyist who has worked with Bob Brookmeyer and Maria Schneider, serving as a production assistant on the latter’s Concert in the Garden and as co-producer on her Sky Blue. “This project began selfishly,” says Truesdell, who was raised in Wisconsin and holds a master’s in jazz composition from the New England Conservatory. “I wanted to learn more about Gil for my own benefit. Many of the available Evans arrangements were inaccurate transcriptions. I needed to go to the source.”

His search led him to the Evans family, to Gil’s widow, Anita, and his son, musician Miles Evans. Truesdell was the first outside person granted access to the family’s archives of Evans’ manuscripts. He found many compositions and arrangements that were long forgotten and never recorded. It was treasure, but Truesdell knew it was incomplete. For example, the family had almost nothing from Evans’ tenure with the Claude Thornhill band; Truesdell found those charts in the Thornhill collection at the Drury University library in Springfield, Mo. He also tracked down material in the personal collections of musicians, and even the Library of Congress. He found complete scores, or sets of parts, or sketches. All of it was Evans music unknown to the world, and Schneider urged him to record it. “People needed to hear this stuff,” she says. “I needed to hear this stuff.”

The opening track of Centennial, “Punjab,” is shockingly unfamiliar and unmistakably Gil Evans. It has his haunting sonorities, his twilight colors from instruments like English horn, flute, bassoon, tuba and harmonium; it has his drama and his silences. Like all of the greatest Evans pieces, it creates its own world. Solos from pianist Frank Kimbrough and alto saxophonist Steve Wilson are deeply in touch with its mystery. “Punjab,” one of two Evans originals on Centennial, was composed for The Individualism of Gil Evans, a classic Verve album from 1964, but inexplicably didn’t make the cut. “My challenge,” Truesdell reveals, “was to be faithful to Gil, and yet to create modern versions of these orchestrations. I had to make assumptions about what Gil would have done in 2012 with a piece like ‘Punjab.’ One thing gave me faith: I knew that Gil never went backwards.”

Other Evans charts that Truesdell rescued from oblivion were originally created for singers. For some reason, “Smoking My Sad Cigarette” did not appear on This Is Lucy Reed, for which Evans wrote arrangements, in 1957. Kate McGarry sings it now, convincingly in character. “Look to the Rainbow” is an arrangement never used for the title track of Astrud Gilberto’s 1965 recording. Gilberto sang it with just a rhythm section and flute. Now the full 12-piece orchestration comes to life, with Luciana Souza lighting up the vocal.

Half of the 10 tracks are charts created for-but never recorded by-the Thornhill band in the late ’40s. One is “The Maids of Cadiz,” famous from Miles Ahead, Evans’ first Columbia Records collaboration with Miles Davis in 1957. But for the album, Evans used only sections of the song and made it a ballad. Truesdell uses the complete 1949 arrangement and gives it a fervent medium tempo. There are sharp solos from alto saxophonist Dave Pietro, trumpeter Greg Gisbert and Kimbrough. Also included is a stunningly modern version of “How About You.” As Truesdell describes it, “The chart has bebop lines and complex cross rhythms trading between different sections, with three piccolos on top. How many big bands were playing bebop with three piccolos in 1947?”

“I struggled with whether I should do only a Thornhill record,” Truesdell adds later. “Everything Gil did came out of the Thornhill band. It was his workshop where he tried new things, like French Impressionist harmonies. He did an enormous number of arrangements for Thornhill. … Only about half of them were ever recorded.”

Centennial is important not only for its research and concept but for the quality of its execution. “Ryan has worked like a dog finding music, copying music, trying out music,” says Schneider. “It’s been a massive project. He now knows this material better than anyone.” And he assembled some of the strongest players in New York for his ensemble. In addition to Wilson, Kimbrough, Pietro and Gisbert, he brought in Joe Locke, Donny McCaslin, Scott Robinson, Marshall Gilkes, Charles Pillow, Michael Rabinowitz, Marcus Rojas, Romero Lubambo and Lewis Nash.

He also used a fail-safe engineer/studio combination: James Farber at Avatar in New York. “Recording the large ensemble required an amazing amount of advance planning,” Farber explains, “since every available channel in Avatar’s Studio A was needed. It took 10 days to mix the album. I proposed mixing to [analog] tape. Ryan instantly fell in love with the detail, richness and depth of the mixes coming off of the tape.” Indeed, one of the major revelations of Centennial is hearing a Gil Evans orchestra, for the first time, in recorded sound approaching state-of-the-art: the clean edges of instruments; the sweeping dynamic range; the huge three-dimensional soundstage.

Besides “Punjab,” the two most significant pieces are Kurt Weill’s “The Barbara Song” and a 19-minute medley, “Waltz/Variation on the Misery/So Long.” Both were done with a 24-piece ensemble, and both have their roots in The Individualism of Gil Evans. “The Barbara Song” appeared on Individualism, and the medley contains early or partial versions of pieces from that record. In 1971, Evans was invited to perform a concert in Berlin and was told he could put together an ensemble of his choosing. He completely revamped “The Barbara Song” and the three pieces of the medley for a large European ensemble. Truesdell found the scores in the possession of the Evans family. On the new album they are vast soundscapes, rapt unfoldings, with denser harmonies than the original versions. Locke’s vibraphone streams in and out of both tracks. Wilson (alto saxophone), Gilkes (trombone) and McCaslin (tenor saxophone) all have stunning moments on the medley. Their solos sound like cries of the human spirit, in defiance of the orchestra’s looming dark forces. Wilson says of this project, “We all came away affirmed that Gil Evans’ music is still relevant.”

Miles Davis once said that Gil Evans could make an orchestra sound like one big guitar. Thanks to Truesdell and company, he still can.