Anaïs Mitchell wanted to keep it simple. In four years, she has released a trio of thematically rich albums, which in their pure inventiveness and musical diversity form a stunning creative hot streak. She has done this with help from a growing cast of collaborators culled from the world of Americana and contemporary folk. But for her latest effort, she wanted to strip it right back to the source.  “When I was coming of musical age, I was really into the coffeehouse scene and Dar Williams and Ani DiFranco, and all those characters were touring solo at the beginning and I would always be disappointed when they finally started having a budget to have drums and bass and stuff,” Mitchell says. “And of course, as soon as I could afford a band, I had one, too. But I always wanted to just make a record of the songs as they were written.”  So this month saw the low-key release of “xoa,” which plays as part autobiography and part love letter to Mitchell’s fans. Featuring the artist on guitar and vocals, unaccompanied, it’s composed of newly recorded versions of songs from throughout her career — notably, including some tunes whose lead vocals were sung by guest artists on the original versions — plus a few that haven’t been heard before. Selections like “Our Lady of the Underground,” “Young Man in America,” and “You Are Forgiven,” heard in these unadorned renditions, should act as catnip to Mitchell’s fans.  “It really is more of a homespun effort,” she says, “for people who are already familiar with the music.” The sound isn’t entirely dissimilar from her earliest work, but the record stands alone as a purely solo effort.  As the Vermont native speaks, she’s in the cafe at the Rock and Roll Hall of Fame and Museum in Cleveland. (Spotting Pete Seeger’s banjo was a highlight, she says.) In the background of the phone call, her 1-year-old daughter contributes a few wordless comments to the conversation. Ramona’s birth, her mom says, helped trigger Mitchell’s current exercise in artistic introspection.  It’s a long tour, and after her show at Club Passim in Cambridge on Monday, Mitchell will carry on with more than two-dozen dates in Europe. This is her first extended solo excursion after spending much of last year touring with New York-based musician Jefferson Hamer behind their album of reconfigured English and Scottish folk songs.  Before that, she had traveled with a band to focus on material from “Young Man in America,” her darkly ruminative concept album inspired by her father and grandfather. And she’s spent much of her time in the past eight years refining “Hadestown,” her folk-operatic retelling of the myth of Orpheus and Eurydice, having released a staggeringly good all-star studio incarnation in 2010. (Mitchell was in residence at Dartmouth College this past August, further developing the show in tandem with New York Theatre Workshop.)  Mitchell’s last two records were produced by Gary Paczosa, an in-demand, Nashville-based engineer and producer who has worked on a dozen albums with Alison Krauss, plus others by Dolly Parton, Chris Thile, and Gillian Welch.  Several artists with whom he was working told him he needed to hear “Hadestown,” Paczosa says. He put the CD on in his studio, planning to listen to one song and then rush out the door to another commitment. “We sat and listened to the entire record. We didn’t move,” he recalls. “I’m rarely that captivated.”  Mitchell says she has no particular interest in writing concept albums — sometimes things just work out that way.  “I think it just happens that songs come in and they bring along a couple friends, or a couple of cousins,” she says. “And they may all seem to be chipping away at the same block, but it just happens to be the stuff that's going through your heart and your head at that time.”  With the most recent addition to the family, she and her husband moved back to Vermont from Brooklyn, where they had spent a few years. She has begun a graduate program in creative writing at Goddard College, pursued remotely through independent study. She’s been listening to a lot of operas and musicals, and wants to sharpen her skills to write another staged production.  She says the new album and current tour are part of the process before “moving ahead into the new era.”  What does the new era have in store?  “Right now it’s that I’m rolling around in a van, and trying to do an MFA program, and trying to jog in the parking lot of the hotel with Ramona in a stroller,” she says. “And I’m trying to go to bed immediately after the gig, rather than having a bohemian evening afterwards.”
Taking a breather after a series of ambitious albums, singer-songwriter Anaïs Mitchell gets back to  low-key basics on her latest album, “xoa.”