Stevie Wonder and his Mu-Tron synthesizer effects machine ad

Today in 1976, Stevie Wonder appeared in the April issue of Down Beat magazine endorsing the Mu-Tron synthesizer effects machine. He used the gadget on his hit “Higher Ground.” The Mu-Tron was a kind of automatic wah-wah effect, and was popular with other musicians of the time including bassist Bootsy Collins and guitarist Jerry Garcia of The Grateful Dead.