WHEN PERCUSSIONIST Jose Medeles was ready to turn some four-track basement demos into a full-fledged, rhythmically focused band, connecting with potential players was hardly a problem.

Medeles is the owner of Revival Drum Shop on SE Ankeny, so his business essentially brings passionate percussionists to him—all day, every day.

"Once I started to think about who I wanted to talk to about [playing together], it was nice to have a drum shop," Medeles says. "You meet the best drummers, potentially, in Portland, and actually get to know them and interview them in a weird way."

Medeles' shortlist of possible bandmates included David Coniglio, a percussionist with a degree from Berklee College of Music and an adventurous spirit. Coniglio was game, and the two formed 1939 Ensemble and released their debut album, Howl & Bite, in 2013. From the get-go, 1939 Ensemble was different: Medeles and Coniglio combined drums, vibraphone, trumpet, and scraps of noise into a propulsive sound that skillfully straddled the worlds of post-rock and avant jazz.

Now, 1939 Ensemble is back with a second album, Black Diamond Pearl, and a third member, Josh Thomas, who brings his horn-blowing from the band's debut, but also adds an entirely new dimension via analog synth. Black Diamond Pearl is aptly named; the album somehow feels sleek and hulking at once, with its basic elements—charismatic drumbeats and reverberant vibes—set against a dark electronic undercurrent. Put simply, the new album is a step up from Howl & Bite, both sonically and in terms of songcraft.

Medeles credits both internal and external factors. "I had more confidence going into this one, because we really worked hard as a band to stay true to what we were doing and we went through a lot of interesting growth spurts," he says. "And now we have some musicians that we really respect that like what we're doing, and that really boosts your confidence."

Black Diamond Pearl was recorded over six days at Tucker Martine's Flora Recording studio, mostly under the guidance of John McEntire, a Portland native best known as a member of post-rock giants Tortoise. Musicians like M. Ward, Tin Hat's Mark Orton, Like a Villain's Holland Andrews, and others visited at various times to help put together the record.

It's Thomas' synth, however, that significantly shifts 1939 Ensemble's sound on the new album. When it enters the mix, the band's songs dive deeper into a gritty groove, not unlike the jazzy jams of Medeski Martin & Wood. And when the synth intertwines with one of 1939 Ensemble's pulsating rhythms, the effect is something like earthy, organic dance music. Soothing elements of instrumental post-rock remain, too. In other words, Black Diamond Pearl is a well-crafted jumble of styles. What's clearer is that it's not so much the musicians steering this ship, but the music that courses through them.

"It seems like everyone's ego is left outside the room. It's really nice. When we get together, we know what we're about and what we want to do," Medeles says. "I've embraced everything that people have [called us]. I don't hold this band so precious that it's this or it's that. I learned that early on. I'm just happy. Whatever you want to call us, we're into it."