The collective quartet performance Op Der Schmelz Live by drummer Klaus Kugel, pianist Roberta Piket, saxophonist Roby Glod and bassist Mark Tokar is rooted in balance yet full of surprises. Most people approaching this record will understand in advance that's a good thing, since surprises are exactly what we hope for when music is played so that anything can happen -- although those surprises are best when they arise from ensemble consistency and purpose, not luck or accident.

While discovering what "anything" will prove to be is the motive for improvised music's players and listeners alike, "anything" is most likely to mean something when practiced hands conduct the explorations; they are the ones most likely to come up with "something" we will want to hear again and again. What's most meaningful in Op Der Schmelz Live are the detailed sonic moments that stir our imaginations, evoke our responses and beguile our ears. These moments, developing into movements, result from the four musicians' individual sensibilities and combined quick wits in unfettered interaction.

Op Der Schmelz means "at the Foundry," the Luxembourg venue where this foursome of distantly based but nonetheless united improvisers concertized in February 2010. Kugel, who serves as the ensemble's point-person though not leader, lives in Koln; Piket is a New Yorker; Glod was based in Strasbourg but has moved to Luxembourg, and Tokar lives in Ukraine. They have worked together for four years. Kugel and Glod go back further, to 2004; Kugel first met Piket and Tokar, separately, in 2007 or '08. Genuinely a band rather than a pickup group, these four empathic individuals concertize as often as possible, although if necessary in smaller combinations. Throughout this program they generate flow by taking risks but also securing each others' moves. With every new foray, no matter how far out they've ventured, the collective arrives at gratifying resolutions.

The six tracks here range from just under six to just over 18 minutes in length. Each sprouts from "heads, very simple things we fill out, not tunes," Kugel says, "which insures they will always sound different.

"I do not feel like a 'free' player in this combination," he continues, mentioning that his ongoing involvement in keyboardist Vyacheslav Ganelin's trio with soprano saxophonist Petras Vysniauskas is a different story. "Here there are so many natural music rules we go by, even when we're not trying to. Our pieces fall into metrical time, for instance. I have a lot of freedom, but I'm not playing 'free.' We're just playing."

Isn't that in itself proof of freedom? But let's not split hairs.

Among the first surprises of this document is Roberta Piket's discursive approach, rather more searching than the progressive yet structured projects she's been known for since her recording debut in 1995 as a sidewoman to Lionel Hampton on For the Love of Music. Roberta's touch opening this live performance with "Dredger of Pig Rolls" has a probing moodiness that seems to belie any associations I can come up with for the title, which was provided by Roby. When the alto saxophonist enters, he and Piket demonstrate an unforced intimacy simply by their graceful tracing of the detailed, kinky line. Roby Glod, by the way, will be an exciting discovery for many listeners. He has a brilliant tone, super-fast fingers, excellent intonation and an engaging musical imagination that extends into his instruments' high register naturally, with no strain.

Mark and Klaus slip in unobtrusively and instantly the quartet has established its cohesive sound. The bassist, of course, provides counterpoint; the drummer, of course, constructs a propulsive foundation that runs steadily but unpredictably, like water over pebbles. After Roby's expansion on the theme, Roberta takes another turn, sustaining the dark but not dire atmosphere, then Mark and Klaus are spotlit, unaccompanied. Each individual actor, some of their functional combinations and also the whole group's sound have been introduced.

"Lviv" is named for the city where Mark Tokar was born. His career has taken him ever farther away from there. Having become recognized throughout Western and Central Europe as an important instrumentalist, educator and festival art director, in 2007 he brought his arco and pizzicato virtuosity to saxophonist Ken Vandermark's international Resonance project; in 2012 Tokar anchored their climactic set at the celebrated annual Chicago Jazz Festival. His solo on this piece might be regarded as a native son's pledge of ongoing allegiance to his hometown -- founded in the 1200s, the cultural capitol of Galicia (the region straddling Poland and Ukraine), locale of some devastating history, a place ancient and proud. Klaus respects Mark's statement with spare accents, as little else need be said.

Klaus explains that "Budmo Hay!" is a Ukraine toast, equivalent to "Cheers!" but this is not your common drinking song. It starts as a soprano-drums feature, Roby's command of his horn impressive and unique: He does not resemble Bechet, Coltrane, Lacy or anyone but himself. Roberta, entering five minutes into the piece, is equally distinctive, building from a few halting single notes to a full-on complex statement, which Klaus matches loosely, using increasingly pronounced cymbal strikes and press rolls. Mark remains in stride up to an unexpected pause, then dips as low as possible, reclaims his midrange with double stops, ends in a nervy bowed episode.

"Nazar" sustains the set's lyrical, reflective ambiance, Roby now on alto, Klaus using brushes, Mark and Roberta offering responses that enrich the experience. "Our music is very intuitive," says Roberta. "It is really completely about intuition and listening. The more you play this kind of music, the better your skills at it become. You have to develop a sense of trust in yourself, so that you can manage the patience you need to wait until the right moment, when you really have something to add. Over time playing together," she rightly maintains, "we've gained a certain rapport."

That rapport is most impressively showcased in the title track, "Op der Schmelz," in which the four musicians work most subtly for almost 20 uninterrupted minutes, at first tapping unconventional aspects of their instruments. A string-stroke here, the pluck of muffled piano wires there, and is Klaus using a bow on the edge of his cymbal while Roby blows through his sax without its mouthpiece on? The hush is enveloping, the musicians' energies intense but suppressed, enabling a one-time-only experience to unfold as a seemingly organic narrative arc.

"What I'm most interested in is the depth of our music, not its form," Klaus says of all their efforts, pertaining perhaps to "Op der Schmelz" especially. "Of course we play in a form, otherwise it would not be music. But form demands we bring colors to use within it. We use our favorite colors, what we have absorbed lately, who we are, from where we've come. Our forms are set up to get us, together, to a deeper place." This track peaks in Kugel's limbs-independent solo and a tag that's been pre-arranged but, expressed like an afterthought, hardly seems so. "Still Alive," the program's finale derived from Ukraine's national anthem, simply restates what's obvious to anyone who's been absorbed in the proceedings.

The goal of musicians such as Kugel, Piket, Glod and Tokar is to conjure fleeting beauty that would be impossible to capture with notes on paper. These musicians trust themselves and their immediate impulses, instead of written, so presumably repeatable, preconditions. Through the recording process, they invite the world – us -- to listen, expecting that we listeners will bring our own personal associations, reactions and circumstances to the experience. So by paying attention to the music of Glod/Piket/Tokar/Kugel you are joining the group. Congratulations! You, too, are now Op Der Schmelz Live.

Howard Mandel, NYC, 2012