Charlie Hunter and Bobby Previte as Groundtruther: Altitude

Altitude continues the pursuit of even greater extremes, this time with keyboardist John Medeski. Spanning two CDs, however, the trio makes a clearer delineation between abstract improvisation and rhythm-centric jams. Disc one, "Above Sea Level, is grounded in groove although, with Previte's electronics, Hunter's effects and Medeski's arsenal of analogue keyboards, there are plenty of colors floating atop the unassailable and, at times, unrelenting rhythms. The recording sounds so big, especially Previte's drum kit, that it feels like a live recording rather than an in-studio recording.

There's a certain globetrotting feel to the first disc, with hints of Middle and Far Eastern harmonies informing tracks like the sloppy but satisfying "Pyramid of Gaza, where Medeski's skewed mellotron and Moog play tag team with Hunter's overdriven and ring modulated screams. That Hunter can continue to maintain a firm pulse, completely in-the-pocket with Previte while going for greater extremes on the top end of his 7-string guitar, remains a marvel.

It's not all about propulsive beats, however. "Everest is darker, with Previte's 1980s-sounding electronic drums—as forward-thinking as Groundtruther is, there's always been a retro feel about the textures—more about open space and ambiance, although it remains jarring and edgy. Still, "Seoul Tower, with Previte's up-tempo, go-go-ish beat, Hunter's bluesy raunch and Medeski's Hammond make it an energetic tour-de-force.

The sixteen miniatures on the second disc ("Below Sea Level ) are polar opposites of the seven lengthier jams on disc one. Abstract and, at times ethereal, they feature a more organic side to the trio, with Hunter's 7-string nylon-string acoustic guitar, Previte's acoustic kit and Medeski'a acoustic piano dominating the set. Still, there's plenty of processing taking place, with the entire set heavily reverbed and sounding strangely submerged, yet crystal clear with intention. As extreme as the grooves are on disc one, the at times aggressive interplay on disc two—with Medeski ranging from classically tinged arpeggios to hammer-fisted Cecil Taylorisms—places the linguistic breadth of everyone on full display. Only "Marlan, the longest track on disc two, builds into a defined and unrelenting rhythm.

A fitting climax to the Groundtruther trilogy, Altitude's combination of rhythm-happy jams, other-worldly textures and visceral free play, affirm Hunter and Previte as a team that's both open to and capable of anything. Hopefully the conclusion of the trilogy doesn't mean the end of this symbiotic partnership.

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