Mengelberg’s boosters claim the idiosyncratic pianist-composer to be a genius, but it is not always discernible on disc, where his playing is oriented more towards process and sensibility than a finished product. Jubilee Varia, however, is an excellent album. Compelling open improvisations and pungent thematic materials function like spark-shooting flints throughout the program. The emotional contrasts are especially stunning within the three-part title-suite: an improvised duet between Mengelberg and drummer Han Bennink dips and surges before finally dissipating; the ensuing trio by bass player Ernst Glerum and cellists Tristan Honsiger and Ernst Reijseger builds a tumultuous head of steam before encountering a sly Latin ensemble, teased and greased by Reijseger, trombonist Wolter Wierbos and clarinetists Michael Moore and Ab Baars. Mengelberg’s “Jealousy” suite functions in somewhat the same manner, juxtaposing carefully shaded ensemble vignettes, full-bore collective improvisations and broad satiric passages, while his “Rollo I” has the tequila-drenched brio of a cantina combo’s theme song-a great set-up for solos by trumpeter Thomas Heberer, Mengelberg and Moore (on alto).