In 1966, Norman Whitfield changed the group's dynamic, moving them away from the previous one lead singer model and adding elements derived from the rougher soul of artists such as James Brown, Wilson Pickett, and the performers at Stax Records.
Most other recordings from this period in 1968-70, such as Cloud Nine and Psychedelic Shack, featured echoed vocal tracks, distorted guitar lines with prominent use of the wah-wah pedal, hard-hitting drums, and various stereo and other sound effects.