You can't turn on the radio without hearing one of Christopher "Tricky" Stewart's hooky anthems. The Atlanta-based producer kicks R&B and pop vocals into overdrive with stomping drums and futuristic keyboard melodies, whether he's channelling a drum corps for Beyoncé, conjuring a barrage of dramatic stabs for Mya's fierce "Case of the Ex" or taking Ciara on a sexy "Ride" with a plush backseat of multi-layered synths.