Miles Davis's 1949-50 "Birth of the Cool" little big band was a major step in jazz, not for its style--its several composers didn't agree on a style--but for its curiously light yet bottom-heavy sound, for its rejection of big-band conventions, and for its repertoire, notably the classic "Israel." Arranger-composer Gerry Mulligan was among the original Cool dudes; he went on to lead his own little and full-size big bands, carrying with him his own feeling for flowing sound, inner movement, and music that warmed, rather than blasted, the listener. Mulligan's concert, billed as "Re-Birth of the Cool," features some of the original Davis band scores and--even better--new compositions. The intricate alto sax stylist Lee Konitz and tubaman Bill Barber are the other ex-Davis sidemen in the tentet; Mulligan's own bariton sax solos have increased in depth of sound and idea over the years, and he and his trumpeter, Art Farmer, share a taste for clean, simple melodies. The program also includes a performance by pianist Ramsey Lewis and his quintet, which features guitarist Henry Johnson. Saturday, 8 PM, Ravinia Festival, Green Bay and Lake Cook Rds., Highland Park; 728-4642.