Terry Riley Keyboard Studies John Tilbury, piano, harpsichord, celeste, and electric organ Another Timbre   In addition to their impressive catalog of music of the moment, the past recordings that are uncovered and released by Another Timbre are frequently astonishing. This is certainly true of a recording of the great new music keyboardist John Tilbury playing three pieces by Terry Riley from 1965: Keyboard Study No. 1, Keyboard Study No. 2, and Dorian Reeds.  Written just after In C, these pieces are foundational as well, presenting the methods with which Riley would assemble solo work from patternings. Like In C,