Sweet Valley is Nathan Williams (frontman of beloved fuzz punks Wavves) and his brother Kynan. Stay Calm is their debut release, 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. Sleeve by Dust La Rock.