Is there anything Bob Brookmeyer can't do? His sinuous, blunt-toned valve trombone has been one of jazz's best-known sounds for the past half-century, while his composing and arranging have won him plaudits for nearly as long. In addition, he's a part-time pianist whose highly personal playing is far more than functional.

But my guess is that his current incarnation will prove to be the most memorable of all. Brookmeyer started his own big band, the Europe-based New Art Orchestra, a decade ago, and "Get Well Soon," the group's third CD, leaves no doubt that he has since evolved into one of the greatest composer-bandleaders in the history of jazz.

What makes Brookmeyer stand out in a very large crowd? To begin with, he's no mere riff-shuffler but a true composer whose grasp of large-scale form is complete and compelling. Most "extended" compositions for big band are ill-fitted mosaics of short-winded ensembles and overlong solos superimposed on repetitive harmonic frameworks. Brookmeyer's music is different. It doesn't just hang together -- it unfolds. Each episode arises organically out of the preceding one, and when you reach the end of a piece like "Elegy" or "Song, Sing, Sung," you know you've been taken on a journey through time and space, not just a quick trip around the block.

No less intriguing is the way Brookmeyer's musical language has evolved in recent years. Now 74, he has pared away the prickly dissonances of his middle-period style. His new music is simpler, more linear, unequivocally tonal -- and full of joy. It's a development one sometimes runs across in the work of major artists as they grow older and strip their vocabularies down to the bare essentials. That's what happened to Matisse and Bartok, and it's what's happening to Brookmeyer. Add to this the unshowy richness of his instrumental palette -- enhanced on "Get Well Soon" by the subtle use of a synthesizer -- and you get music that challenges the ear while warming the heart.

Brookmeyer's music isn't easy to play, but the crack instrumentalists of the New Art Orchestra have unlocked its secrets and make them manifest with total assurance. (That goes double for the guest soloist on "Get Well Soon," a wonderful young German trumpeter named Till Bronner of whom much more will surely be heard.) Earlier this year, the group made its American debut, blowing the Vanguard Jazz Orchestra off the stand in a head-to-head "battle of the bands" at New York's legendary Village Vanguard. Much of the music played that night is on "Get Well Soon," and although there's no substitute for hearing a big band live and in full cry, this CD comes as close as is humanly possible.

Together with its predecessors, "Waltzing With Zoe" and "New Works (Celebration)," "Get Well Soon" represents the state of the art in large-ensemble jazz, the crowning achievement of a septuagenarian master who has never sounded younger than he does right now.