Sigge Krantz, Hanna Östergren, and Reine Fiske join Jakob Sjöholm in Träden. Sara Shahbazi

Off and on for 50 years, Swedish group Träden (formerly Träd, Gräs Och Stenar—Tree, Grass and Stones in English) have been making trance rock of solemn yet ecstatic majesty. Their marathon workouts may seem easy to create, but it's difficult to generate the precise textures and conceive the choicest chord progressions that trigger the deepest feelings of transcendence. The line between sublimity and monotony is slim, and most bands topple into the latter when working in this mode. Träden nail it, time after time.

As the band prove on their 2018 self- titled LP, Träden still have the golden touch, conjuring an elemental elegance and baleful blissfulness for 70 blessed minutes. They demonstrate that if a riff sounds magnificent one time, it will sound even more monumental the hundredth time. The cumulative power they achieve astounds. From deep in their catalog, which Anthology Recordings reissued in 2016, check out "Chrisboogie" from 1973 LP Mors Mors, a 12-minute exemplar, and their cover of the Rolling Stones' "Last Time" stretches it to nine minutes of bucolic, cyclical hypnosis.

With roots in the 1960s Swedish anarcho-commune scene and the cosmic minimalism of Terry Riley, Träden began as Pärson Sound, then morphed into Harvester, then International Harvester, before settling on TGOS for more than four decades. With the deaths of original members Torbjörn Abelli and Thomas Gartz, and the retirement of Bo Anders Persson, guitarist/vocalist Jakob Sjöholm changed the name to Träden to signal a new era. Dungen's Reine Fiske, Archimedes Badkar's Sigge Krantz, and Hanna Östergren of Laughing Eye have joined Sjöholm to help create the juggernaut that's coming to Seattle on April 24.

Even though they sound nothing like the original wave of punk, TGOS felt an affinity for the genre's DIY spirit. "We built our own amplifiers and cabinets and even our instruments by ourselves," Sjöholm says in an e-mail interview. "We experimented with constructing different kinds of loudspeakers to try to get the best sound on stage. This was before the time of monitors. And after a while, we even built a PA system with monitors. We did all the work down in Bo Anders's basement. It was [because] we didn't have the money, but mostly because we wanted to understand how things worked and to be in control of our situation, and not depending on any labels or promoters. That's also why we were part of starting the outdoor festivals in Sweden."

Sjöholm agrees with my observation that duration, minimalism, and repetition play a crucial role in Träden's music. "It's like some kind of religious service, almost like praying, shamanism.

"We started the sessions by repeating, and that was very deliberate and we knew exactly what we were doing. But after a while, you lose control and something else takes over. We try to create one sound, a big drone that everyone contributes to. And in the best of moments, it is like everyone in the band is at the steering wheel, but no one has to take over."