David Grisman/Denny Zeitlin: New River

Take two exceptional San Francisco Bay-area musicians with exceptional backgrounds-Denny Zeitlin is a both a practicing psychiatrist and a world-class pianist; mandolinist David Grisman came out of bluegrass to play with a number of jazz luminaries-and this series of vibrant duets is what you get. All of the material is original, with each participant bringing four numbers to the table (one tune is a collaboration).

Zeitlin’s “Brazilian Street Dance” begins spaciously, almost cautiously, before upshifting to a kinetic samba groove, with Grisman’s mandolin dancing over the piano underpinning. During the keyboard solo, which makes several transitions and freely ranges, Grisman actively comps, reenters for counter-line episodes and is rarely at a loss for what to do. In contrast, Grisman’s “Fourteen Miles to Barstow” is a progressive, folklike conversation that includes a variety of string effects, articulate exchanges and expansive, probing work by Zeitlin. And the project’s joint effort, “DG/DZ Blues,” touches on minor blues elements that serve as a jumping off point for exploratory work by both players, Zeitlin in particular.

One of this album’s most admirable facets is that the mandolin and piano work very well together in terms of timbre and range. But the program’s most intriguing feature arguably is Zeitlin’s apparent tendency to dare Grisman to keep up, which adds to the overall spontaneity and unpredictability.