No conductor. Few tuning forks. A sound all their own. Philly’s Variant 6 choir is breaking out.

Variant 6, Philadelphia’s emerging, enterprising chamber choir, is best defined by what it doesn’t do — or have. No leader. No conductor saying what to sing. Or how to sing it. Or where: Traditional concert halls aren’t among their favorite things.

None of the six members in this ensemble of busy Philadelphia freelance singers has perfect pitch. Tuning forks are seldom used. Yet chords are so perfectly tuned that their blends almost sound electronic on the group’s first full-length album New Suns, which is being released in conjunction with its concert 8 p.m. May 21 at University Lutheran Church and shows what, amid so many “nots”, Variant 6 does do.

“We look for pieces that require virtuosity,” said soprano Rebecca Myers — “that explore the potential of the human voice and how far we can stretch that.”

It’s high-wire unaccompanied singing that leaps into unexpected gestures and with arresting harmonies. But as much as the voices exclaim and argue at high speed on New Suns (released on the Open G Records), they stop short of the kind of avant-garde vocalization that stretches the definition of music. Composers on the album include Gabriel Jackson and Benjamin C.S. Boyle, who are familiar to audiences of the larger modern music group The Crossing, in which the Variant 6 members also sing.

Meanwhile, Variant 6 is developing its own pool of composers, sometimes blurring the line between concerts and theater, such as Wally Gunn, whose Moonlite explores the life of a 19th-century gay Australian outlaw known as Captain Moonlite. The group also goes for ancient, even medieval music that can be far more strange. “Next season we’re doing a piece that was found in a New Orleans monastery,” said Myers. “I don’t think it’s known who wrote it.”

Also in their repertoire: Handel’s Messiah, though for that, the group expands to a 12-member variant. Such flexibility is part of the idea. “We like being pulled in directions we might not have explored otherwise,” said mezzo-soprano Elisa Sutherland. That’s appreciated when collaborating with a wide range of Philadelphia groups, including Bowerbird (which often presents its concerts), Lyric Fest, and the emerging baroque group Filament.

“I’ve always wanted to have an outlet for my own creative ideas,” said Sutherland. “I and other members get to sing under the best choral conductors in the world. And we love doing that. But I also like to make my own programming decisions.”

The members would have to be strong-minded to maintain the group name during the pandemic. “If the sixth variant ends up being the COVID that starts killing off the human race,” said Myers, “we’ll have to change our name.”

To look at the group, you’d never guess such a diverse collection of people would have such a meeting of the vocal cords. Is this a random collection of people — hipsters, grad students, and a potential fashion model — who got stuck in the same elevator? In fact, they’re the best of friends and have epic-length text message threads to prove it, which allows the group to be scrupulously democratic. No idea is unexamined. “Working closely with your friends … greatly enhances your responsibility to give everything you have,” said tenor Steven Bradshaw. “You wouldn’t be honoring the friendship if you were phoning it in.”

From that came a determination to finish the New Suns album, which was begun in November 2019 in a Chestnut Hill venue, went on hiatus, and then was finished July 2021 in Flourtown. In between was a miniature lifetime. Soprano Jessica Beebe announced at the end of the first sessions that she was pregnant. By the 2021 sessions, her son took his first steps. “We all went through big changes … and returned to it more self aware, more appreciative,” said Myers.

The original idea for the group was hatched between Myers and Bradshaw at Stateside, the neighborhood oyster bar on East Passyunk Avenue. The concept was to create a smaller ensemble among their favorite colleagues who also happen to sing with them in The Crossing, but something modeled after a leaderless string quartet. “Our first meeting was October 2015, and we had so much fun bouncing ideas off each other and forming plans, … just six friends who wanted to make music on their own terms,” said Beebe. The debut performance at an art gallery was expected to draw an audience of 25. Instead, the number was 75.

As it shaped up, the members are between the ages of 28 and 41, and have become so busy post-lockdown that they strain to keep track of each other; members mostly had to be interviewed by e-mail. Both Sutherland and tenor James Reese have solo careers, she with Brooklyn Art Song Society recitals, he with the Philadelphia Chamber Music Society, and both just finished a tour of England with the New York-based early-music group TENET. Bradshaw — also a noted Francis Bacon-influenced visual artist who designed the New Suns album art — has been playing the central role in Place, a Pulitzer Prize-nominated stage work by Ted Hearne.

Bass Daniel Schwartz directs his own choir, Voices of Pride, and teaches private voice at Haverford College. Myers sings with the Cleveland-based Apollo’s Fire and the Miami-based Seraphic Fire. Most of them sing or have sung with Opera Philadelphia and are particularly handy with their contemporary works: Myers and Beebe played secondary roles in The Wake World, an acclaimed David Hertzberg opera presented at the Barnes Foundation. As a soloist, Beebe will sing the Mahler Symphony No. 4 with Lancaster’s Allegro Orchestra and records with the Boston-based Lorelei Ensemble.

Rehearsals are feats of scheduling and may well be as interesting as the performances. Certainly, they’re longer because everybody has their say. One member is nominated to come up with a rehearsal plan and see that the group sticks to it. Only five minutes of off-topic banter is allowed. “You choose your battles. … You learn to know when to take charge, and when to fade into the background, " said Schwartz, “and somehow this makes our different personalities shine through in the performance.”

“We often know what someone else is likely to feel about a certain musical decision before it is voiced,” said Bradshaw. “Jimmy [Reese] and I have played a game where I’d offer his opinion and he would offer mine.”

The difference is that, come concert time, they aren’t just singing.

“When we have had the time to really rehearse and understand a piece of music, and when everyone is buying in to the interpretation,” said Sutherland, “I think there’s a very special sound we get.”

“There’s nowhere to hide in Variant 6. If the music doesn’t fly off the page, there’s no director, conductor, … it’s on us and us alone,” said Bradshaw. “So we’re all giving our insight in an effort to make maximum impact … because if someone got a babysitter or drove around looking for parking to attend our show, we’re gonna bleed for you.”

The Variant 6 “New Suns” release concert is 8 p.m. May 21 at the University Lutheran Church, 3637 Chestnut St. Tickets: $15-35. Information: variantsix.co The group will also perform at 7:30 p.m. May 20 at National Sawdust in Brooklyn.