Chuck Mangione: ''Journey to a Rainbow.'' (Columbia Records FC 38686.) This is the latest edition to the Mangione legacy started back in 1962. Mangione doesn't take any new roads with this album. Typical Mangione, ''Rainbow's'' beauty lies not in its face value - which can appear shallow - but in the combination of elements that make up the whole. Listening to this album on anything less than a terrific sound system would be a shame. One needs to hear the subtleties, the inner workings - the crispness of the cymbals; the cracking thud of the bass drum; the chord progressions, each enhanced in its own way by the pianist, guitarist, and bass player - all need special attention to realize the final product. The ballads are smooth, the funky stuff is lively, and the fusion is spicy. All Mangione compositions, the melodies are often carried by Chris Vadala on flute or saxophone, or by Mangione's limited, but tender flugelhorn. Although Mangione has been redundant in the past, he stays away from a lot of repetition here. A variety of styles from cut to cut, and within numbers, keeps the album interesting all the way through. No words to ponder, Mangione's message is music, pure and simple.