When Milwaukee trio Argopelter begins its debut performance this Saturday, it will be the first time anybody at Club Garibaldi—or anywhere else for that matter—will hear that particular song. And yes, “anybody” also applies to members of Argopelter. The new project is composed of three well-respected musicians hailing from different corners of the music spectrum who intend to perform entirely improvised material, completely on the fly.

Oddly enough, Argopelter has none other than Marvin Gaye to thank for its formation. Field Report front man Christopher Porterfield; Barry Clark of electronic project adoptahighway; and jazz drummer Devin Drobka of Bell Dance Songs and Lesser Lakes were grouped together for Alverno Presents” production of the Gaye-inspired “Unlooped,” which took place at the university March 1. Clark and Drobka have played together since middle school, but neither had met Porterfield until the three rehearsed for the first time.

“We started playing and things just started working,” Porterfield says. “The piece we did was a really loose piece and they were able to follow the instincts I had completely non-verbally. Even if it was a weird or ill-advised place to go, they were just there. It was incredible. It just fell into place remarkably well and it was super freeing to work with those guys. After the fact, I was chasing that feeling again. I wanted to do it again, and they did too.”

After the “Unlooped” performance, the trio continued to get together. About once a week (usually a weekday morning), the once-assigned partners met of their own volition to “rehearse”—though not much material was being re-heard during the sessions. Porterfield, Drobka, and Clark quickly abandoned any semblance of a founding idea or search for overlap in musical preference, instead favoring an approach tied to the pillars of improvisation, experimentation, and presence in the moment.

“The basis of improvisation is communication, and every time we play together as Argopelter, we learn more about how to communicate with one another,” Clark says. “There’s no ego and everybody is just listening to each other. It’s really malleable in the sense that if it goes one direction, everybody is going there.”

With Clark on upright bass, Drobka drumming, and Porterfield playing guitar in addition to sporadically singing, Argopelter travels to a myriad of places. It culls from Clark’s electronic background and symphony experience, as well as Drobka’s extensive jazz and experimental acumen. However, the free range format most often lands on the outskirts of Porterfield’s familiar neighborhoods of folk and Americana.

“This is just something that stands on its own merit and on the strengths of Evan and Barry, and it doesn’t require a whole lot of nurturing from me,” Porterfield says. “Those guys are capable of taking anything anywhere, and I am not. So anything that we’ll do is probably going to be kind of rooted in folky, American traditional stuff. They dress up what I do in ways that leans a little more experimental with a jazz influence.”

Despite the lightly drawn parameters, the usually lyric-anchored Field Report bandleader occasionally avoids singing altogether. Sometimes the trio abandons an effort three minutes in and starts another. Other movements can climb close to an hour in length—ebbing and flowing to numerous parts of the sonic landscape, and (if done right) sounding like something that existed before that very moment.

“When we’re improvising these songs, we try to make it sound like we wrote them, but it can kind of take any approach we’d like,” Drobka says. “For me, it’s just freshness. To improvise well, you have to be 100 percent present. I love being on the edge like that, with the immediacy involved in making something while people are watching. If this sucks, it’s really going to suck. But if we’re really focused, and listening, and committed, it’s going to be great.”

The members of Argopelter relish the immediacy of the process and the collective abandonment of all individual creative comforts. Porterfield says the approach has helped him improve what he does in Field Report as well.

“They’ve stretched me out musically and given me confidence in just trusting the moment,” he says. “It’s like trying a new thing at the gym…I hear from people who go to the gym. [Laughs] It’s trying a new workout and having new muscles be sore, but it feels really good and you want to keep working on those muscles.”

That said, those musical muscles might atrophy soon, as Field Report is on the cusp of extensive touring behind its forthcoming album. Clark is occupied with adoptahighway and playing bass in local symphonies, and the self-proclaimed “mutt” drummer Drobka splits time in his local groups, as well as acts as a session drummer for artists on both coasts. Clark and Drobka also co-host the monthly “Unrehearsed” series at Jazz Estate. With no more shows on the books, and no record planned at the moment, Saturday will likely be the only chance to see Argopelter in the near future. It will certainly be the only time to ever hear those particular stream-of-consciousness compositions played live.

“There’s something really special about that experience—that you were there when it was happening,” Clark says. “Sure, it can be recorded and played back again, but it’s never going to quite be that experience again. We’re all in it together.”

Much like the mythological tree-dwelling and stick-tossing monster from which the project derives its name, Argopelter plans to throw whatever it feels like in the direction of anybody in the vicinity and see if it strikes. Maybe someone will be impacted by a musical moment in time. Perhaps the point of the unconventional concept will miss most in attendance. No matter how the inaugural Argopelter experiment is received, it will simply be a fleeting performance art installation that can never be captured in quite the same way it was created.

“I’d rather it be ‘Oh well!’ than ‘What if?’ so we’re going to do it and see if it works,” Clark says.

Argopelter plays its first show Saturday, July 12 at Club Garibaldi, opening in support of The Caribbean (Washington DC) and Peter Wolf Crier (Minneapolis). The show begins at 9 p.m. Argopelter will NOT play the song embedded below.