The press paraphernalia that accompanies the arrival of any new CD almost by definition is bound to make some pretty bold claims — how else to make one disc jump out from the piles that land every week? Even so, a press release for “only sky,” David Torn’s new disc on the ECM label, includes a line that gives pause: The succinct road trip that brings Torn to Regattabar in Cambridge on Wednesday is the protean guitarist’s first solo US tour in two decades.  Torn first stepped into the public eye in the early 1980s with Everyman Band, his fellow musicians a trio of Lou Reed alums with whom he recorded for ECM. He has since plied sinuous lines and textural whorls alongside David Bowie, John Legend, k.d. lang, and Tori Amos, and in prog-jazz all-star quartet Bruford Levin Upper Extremities (B.L.U.E.). As a producer, Torn now has a client list that includes Jeff Beck and Kaki King. Soundtrack work, alone and in collaboration with Carter Burwell, Howard Shore, and Cliff Martinez, has increased steadily, as well.  Clearly, he’s kept busy. But two decades? Really?  “I did a lot of touring with different bands in the late ’90s, early 2000s,” Torn says by telephone from his home in upstate New York. “Then after the last B.L.U.E. band, I pretty much stopped.” He’s continued to play in Brooklyn, N.Y., he says, “because I don’t have to advertise; I can just show up and play.”  Prezens, the quartet with which Torn returned to ECM in 2007, has toured Europe, but only played perhaps six dates in the United States. In 2012, he took a trio to Brazil. “But I haven’t really been focused on these things at all,” he says. “I don’t think I’ve actually toured solo since . . .” He pauses, cogitates, mulls a few names. “Maybe it was 1994?”  A contributing factor in Torn’s decreased visibility was the health crisis he faced in 1992. Diagnosed with a non-cancerous brain tumor, he underwent surgery, and lost hearing in his right ear. Still, he says, he was traveling to Germany for studio work less than a year later, and was touring again by 1994.  “I had to go carefully,” he says. “Even in the early 2000s, I still had some difficulties. Up until five years ago, I was still working on different medications all the time to keep the swelling down.”  Somehow, he still slipped beneath the radar. Scanning social media recently, Torn came across a journalist who was crowd-sourcing questions to ask him in an upcoming interview. A common reply: Ask what he’s been doing since “Cloud About Mercury.” That’s Torn’s most famous album, sure, but it came out in 1987.  “Just because I haven’t been playing live doesn’t mean I haven’t been making music in an active way,” Torn says, recounting what he told a concert promoter who was quizzing him about his past track record. “I’ve been so productive for the last 20 years that nobody knows what I’m doing — it’s pretty amazing — the hundreds of films and a million records, whatever.”  That’s not hyperbole. It’s Torn’s guitar you hear oozing through the seams in John Legend’s breezy 2007 hit “P.D.A. (We Just Don’t Care).” Likewise, Torn’s brittle stutters on “Sunday,” the opener on David Bowie’s 2002 LP, “Heathen,” set an eerie tone that permeates the album, the first of three that Torn has made with Bowie (including “Reality” and “The Next Day”).  By contrast, the music that Torn creates with Prezens — saxophonist Tim Berne, keyboardist Craig Taborn, and drummer Tom Rainey — is some of the most unshackled playing he’s committed to record. Berne, who hired Torn in the late ’90s to master live tapes for independent release, and then engaged him to produce a series of new albums, came to view him as a bandmate.  “I think he’s brilliant; if he didn’t play guitar, he’d be brilliant just in this mixing, recording stuff,” Berne says by telephone from Brooklyn. “As a guitar player, as a musician, he’s one of those guys who, when you’re playing with them, it’s never about a style. It’s always like, OK, we’re playing music, and whatever you’re not doing, I’m going to do, and somehow together it makes sense.”  On “only sky,” Torn works completely alone, conjuring with guitar, oud, loops, and effects pedals instances of spacious calm, folksy rusticity, stormy roiling, and industrial clangor. The music he’ll play at Regattabar, he says, will be consistent with what’s on his CD, but not identical. It can’t be, because Torn hasn’t played a single gig since B.L.U.E. ended that wasn’t completely improvised.  “I just had this thing that started at the end of the ’90s: This is what I like, this is what I do,” he says. “I don’t want to sit down and write material for a band; I want to gather people around me and play with smaller groups, where hopefully there’s going to be some kind of ability to develop a vocabulary together, or do it on my own, and not think about all that stuff that I do when I sit down and struggle over five minutes of written music.”  Tickets: $25, students $20. 617-395-7757, www.regattabarjazz.com
David Torn, a protean guitar improviser who also keeps busy as a sideman, producer, and soundtrack composer, comes to Cambridge on Wednesday on his first solo tour in two decades.