These days there’s always more top-shelf live jazz in town than you can get to — the Regattabar and Scullers are booked solid from Tuesday to Saturday night or even Sunday, Ryles is going strong, avant outposts like the Zeitgeist Gallery and the Artists-at-Large Gallery in Hyde Park keep pushing the outer limits, and that’s not to mention marauding jam sessions by the likes of James Merenda at places like Costello’s in Jamaica Plain, the Chopping Block in Brigham Circle, Matt Murphy’s in Brookline, and Good Life in Central Square.

This week I skimmed just three shows off the top (for a fourth, see Ed Hazell’s review of the Fred Hersch Trio in "Live and on Record," As it turned out, they were three bands that emphasized ensemble cohesion and unity of sound over solo derring-do — which doesn’t mean there wasn’t plenty of the latter.

Back in 2000, the collaboration between the Bob Nieske 3 and the Lydian String Quartet, Simplicity (Accurate), was unusual in that, unlike jazz/strings collaborations of the past, it didn’t use the strings merely to provide lush, sweetening harmonies behind a soloist. Nieske said that his inspiration was the combination of trumpet and strings in Charles Ives’s The Unanswered Question and On the Pond. Thus, he likes to set up a bit of dissonant tension between trumpeter Phil Grenadier and the quartet, or trade zippy zigzagging "fours" between the quartet and drummer Nat Mugavero. There’s no "chording" instrument like piano or guitar, so Nieske can leave open spaces of implied harmonies and get a sound that’s at once lush and austere.

At the Regattabar a week ago Tuesday, as on the CD, Nieske mixed pieces for trio-only with trio-plus-quartet, and in the first set he left the Lydians alone at one point to play the first movement of the Ravel String Quartet ("Bill Evans’s favorite composer!" piped up Lyds cellist Joshua Gordon). Otherwise, everything was a Nieske original. In keeping with his album title, he builds his pieces on simple foundations — a bass ostinato, a tango rhythm, the blues, or, as in a long suite that was unveiled in the second set, a recurring, gently rocking interval of a minor third that served as a guiding thread through the piece. Even a complex line like the title track ("stolen," says Nieske, from the first six notes of Ornette Coleman’s "Congeniality") is engagingly boppish. The most "free" passages were held by a lyric narrative tension.

Grenadier and Mugavero were canny minimalists, Grenadier leaving plenty of space as he pecked through Nieske’s melodies, or resolving on expressive flatted or "cracked" notes. At times, when the Lyds joined in on a minor key, the effect was of Miles Davis on Sketches of Spain. Mugavero, meanwhile, played with the economy and grace of an out-there Connie Kay, matching a heartbeat rhythm to the perfect tone color, the hard, the bright sound of a stick tapping the edge of a cymbal, or the thump of mallet against his equipment case. Nieske himself joined Charlie Haden–like big-toned melody and abstraction with multi-note dexterity.

Listening to the antiphonal interplay between violinist Dan Stepner and violist Mary-Ruth Ray in the Ravel, I found myself wishing that for future pieces Nieske would break down the ensemble into similarly smaller units and "inner" voicings, so as to make the demarcation between quartet and trio even more interactive and porous. But that might also require some improvisation on the part of the Lydians.

THE QUARTET SPHERE began as more or less a Thelonious Monk tribute band (their first recording session took place the morning Monk died, February 17, 1982), with Monk band alumni Charlie Rouse and Ben Riley the prime movers. But they developed their own repertoire and worked through the mid ’80s, then disbanded a year and a half before Rouse’s death, in 1988. In the ’90s, survivors Riley, Kenny Barron, and Buster Williams found themselves working together as a trio, and soon there were questions about re-forming the band with a new saxophonist. Enter alto- and soprano-sax man Gary Bartz, a new recording in 1998, and the resurrection of one of the most elegant small groups in the music.

At the Regattabar on Thursday night (the first show of a weekend stand), every note rang with clarity — that due to the club’s soundman, yes, but also to the band’s exquisite internal dynamics. Because of those dynamics, you can hold all four parts of Sphere’s music in your head at once and savor them: pianist Barron chopping up the rhythm with some block chords behind Bartz’s pure, legato phrasing of the melody, bassist Williams stepping back and forth between abstract figures and straight walking fours. As colorist and timekeeper, drummer Riley finds an infinite variety of ways to subdivide the beat, and he can get a sound from brush against cymbal that’s as full and rich as a major chord.

In Bartz’s earlier years, he was known for playing with Coltrane-like ferocity. In Sphere, all his intensity goes into timbre, phrasing, and note selection, and his pitch has a piquant sharpness that can recall both Jackie McLean and Roscoe Mitchell. During the first set, they played the Leon Robin–Ralph Rainger standard "If I Should Lose You," Bartz’s "Uncle Bubba," Barron’s "Cook’s Bay," Monk’s "Reflections," and Rouse’s "Pumpkin’s Delight." Barron’s legato treatment of the Monk — contrasting with the composer’s percussive attack — gave it an air of nostalgia commensurate with the title.

SINCE HIS DAYS as a jazz crossover superstar on the psychedelic-rock circuit in the late ’60s, Charles Lloyd has always had a reputation for casting an aura. These days, as he rides on a series of all-star sessions for the ECM label, that aura has taken on the glow of late-career mastery. On Saturday, the second of two nights at Scullers, his band included pianist Gerri Allen, guitarist John Abercrombie, bassist Bob Hurst, and drummer Billy Hart.

Lloyd is explicitly spiritual when he talks about his music, but that doesn’t mean it’s empty-headed. Memphis-born and weaned on youthful gigs with the likes of B.B. King and Bobby "Blue" Bland, he’s rooted in the blues and his own kind of expert showmanship. He began Saturday’s set with Billy Strayhorn’s death-bed composition "Blood Count," and though he edged into the tune on a whisper, he hit the top note of the first phrase with ardent, full-bodied authority. This kind of drama suffused the set. He lavished his light, rich tone on ballad melodies, but on up-tempo numbers he conjured Coltrane’s skittering runs and even edged into the realm of free jazz, all of it grounded in the band’s explicit pulse and harmonies.

The band tapped into the Lloyd aura. The flute feature "Beyond Darkness" was built on a three-note ostinato in bass and piano and tinged with Eastern scales, the tension ratcheted up by Hart’s rapid brush-on-cymbal triplets behind the static harmony and slow melody. Abercrombie was his usual harmonically exploratory self, and when Hart hit a hard backbeat on "New Blues," he answered with biting blues cadences. When Lloyd reached a beseeching cry on the bridge of "Go Down Moses," Abercrombie answered with his own vocal-like response.

Maybe the most Lloyd-like band moment came when Allen, bringing the dynamics of Billy Preston’s "You Are So Beautiful" down to a hush, picked out simple single-note variations on the melody and ended the tune in mid phrase. Lloyd turned to her smiling, hands held in a salaam, then offered it to the audience as well and was gone.

IN THE AVANT-GARDE, saxophonist John Tchicai has his own aura. Born in Copenhagen of a Congolese father and a Danish mother, he hooked up with Americans like Archie Shepp at European festivals, then moved to New York to work in such seminal ’60s bands as the New York Contemporary Five and the New York Art Quartet. In 1965, he recorded on Coltrane’s epochal Ascension, and his reputation was sealed.

The tall, imposing Tchicai has worked mostly in Europe since the ’70s, but in 1992, while living briefly in California, he met Boston’s Either/Orchestra. At the Boston Creative Music Alliance’s first concert at the ICA, in 1993, he joined the E/O for an all-Tchicai program. Several years later, in 1998, he recorded with E/O saxophonist Charlie Kohlhase’s band on the Nada label, Life Overflowing. Now he’s back to play an anniversary concert with the Either/Orchestra for the BCMA at the ICA this Saturday, February 1. (For information, call 617-628-4342.)

What is it about Tchicai that makes him a hero? "He’s authentically of that free-jazz generation who came of age as mature musicians when that music was being invented," says Either/Orchestra leader Russ Gershon, "so he has a different relationship to it than we do, being a generation or two younger. I guess that shows that free jazz is a historical period of jazz, like swing. It’s like playing with an old swing player — there’s just a different kind of swing when you’re playing it with people who were playing it when it was new."

As for writing and playing, Gershon points to Tchicai’s cosmopolitan background and his affinity for African soukous (he’s been part of Pierre Dørge’s New Jungle Orchestra) as well as the avant-garde, parade rhythms, and the European cabaret tradition. Gershon is anticipating a special affinity between Tchicai and this latest edition of the E/O, which includes Surinam-born drummer Harvey Wirht and Dominican percussionist Vicente Lebron.

Answering an e-mail query, Kohlhase adds that Tchicai is "one of the masters of tone and time" and cites him as "our solidest embodiment of Lester Young’s true tradition. . . . I recall hearing him play a phrase when we were recording and thinking, ‘I’m not going to be able to blow that back in his direction quite the way it came to me!’ "