Ah Um is one of Charles Mingus's most richly textured albums, dense and dynamic all at once. It is almost as if the whole of the jazz tradition to that date, and some vision of its immediate future, were crammed into three-quarters of an hour.
It is not as ambitious as The Black Saint and the Sinner Lady (1963) and still retains some measure of conventionality in the structures of some of its constituent pieces: introduction, ensemble statement of the theme, solos, development, recapitulation, closing statement.
Peculiar wails weave themselves in and out of ironic quotations from Ellington, from Mingus, from the blues, all cloaked in the enormity of the Mingus sound, thrust forward by rhythms and counter-rhythms tightly driven by Dannie Richmond. It contains the passionate, aching "Goodbye Pork Pie Hat". An indispensable album.