Iowa-based soul revivalists The Diplomats of Solid Sound add female vocals on a number of tracks for their latest CD. It’s an enjoyable though somewhat predictable listen, as the Diplomettes croon their man-done-me-wrong (or right) lyrics with a sultry swagger over lively horns, hammond organ and funky bass and drums. When they’re at the top of their game, as on “B-A-B-Y,” their music channels the essence of the Stax giants from decades past. When they’re not, they venture into territory more suited for the house band on Saturday Night Live.