In the press release that accompanies Michael Chapman's 2017 album 50, the iconic British guitarist refers to it as his "American album." While the material does sound less idiosyncratically British than much of Chapman's body of work, 50 could be more accurately described as his indie rock album.

He's best known as a master of the acoustic guitar, but on these sessions, the dominant instrument is the electric guitar of Steve Gunn, who also produced the sessions.

Gunn assembled a band of like-minded musicians whose passions encompass indie rock, experimental rock, and the more abstract corner of Americana, and while Chapman's impassioned vocals ride over the top and his acoustic guitar is audible in the mix, the band doesn't bow to Chapman so much as encourage him to keep up with them.

It's significant that six of the ten songs on 50 are numbers Chapman has recorded before, and while the new interpretations are bold and often muscular, these new takes recast the music in a more aggressive and less folkie manner than one might expect from him.

If the spotlight seems less tightly focused on Chapman on this album, he certainly sounds engaged with the music, and his vocals on numbers like "The Mallard," "Memphis in Winter," and "Money Trouble" are strong and defiant, bringing his stories of lives along the margins to vivid life.

And even though Gunn and his cohorts threaten to steal the show with their folkie but clamorous brand of indie rock, the heartfelt racket summoned by Nathan Bowles, James Elkington, and Jimy Seitang fits Chapman's music better than one might expect.

(Besides, venerable U.K.

folk singer and songwriter Bridget St.

John is on hand to keep Chapman company and contribute vocals.) Chapman is an artist who has never had a problem with upending creative expectations, and if 50 isn't the sort of music many of his longtime fans would expect from him, it's also passionate, literate, and the work of an artist who wants to make the most of his late-era career.

Not many artists sound this determined and engaged, especially at the age of 75.