Beethoven's "32 Variations on a Waltz by Diabelli, Op. 120," have been programmed before with other variations that were published by Diabelli in a two-part volume along with Beethoven's set, and contemporary composers have written new variations on Diabelli's "original waltz," but the program of pianist Rudolf Buchbinder's Diabelli Project is unique. Buchbinder offers a three-act sequence beginning with Beethoven's set and concluding with variations from the original Diabelli group, ending with the fine, brilliant coda by Carl Czerny. In the middle are contemporary pieces commissioned by Buchbinder and includes variations by several compositional heavyweights. One is the nearly nonagenarian Rodion Shchedrin, whose variation is delightful. Other highlights are the atmospheric "Blue Orchid" of Tan Dun and the variation by Jörg Widmann, who, unlike several of the others, writes a "true variation on Diabelli's waltz" rather than on one of Beethoven's variations. The original Diabelli variations include an impressively ambitious piece by the 11-year-old Liszt, one by Schubert, and one by Franz Xaver Wolfgang Mozart. Buchbinder's "Beethoven set" itself is straightforward and well-crafted; there are more dramatic versions, but his works well in this setting. The sound from Berlin's Jesus-Christus-Kirche is not ideal and robs the contemporary works of spontaneity, but this is an important entry in the continuing history of the Diabelli variations.