Preheat waffle iron according to manufacturer's directions. In a medium bowl whisk together the flours, soda, baking powder, salt, and sugar. In another bowl beat together eggs and melted butter, and then add the buttermilk. Add the wet ingredients to the dry and stir until combined. Allow to rest for 5 minutes. Ladle the recommended amount of waffle batter onto the iron according to the manufacturer's recommendations. Close iron top and cook until the waffle is golden on both sides and is easily removed from iron. Serve immediately or keep warm in a 200 F oven until ready to serve.