Sweet Valley is Nathan Williams (frontman of critically beloved, fan favorite fuzz punks Wavves) and his brother Kynan. Stay Calm is their debut release (out 8/7 on Fool’s Gold), an instrumental beat tape that doubles as an awesomely lysergic postcard from the outer reaches of pop USA. Whether screwing American Bandstand breaks on “Total Carnage” or whipping out g-funk synthesizers on “Dunk Dreams 95,” the brothers Williams have managed to craft the perfect black hole summer soundtrack. Grab the sunscreen, nod your head, and mind the sharks…