In a small bowl, stir 1/2 cup sugar and 1 teaspoon cinnamon together. Butter a tube pan well and liberally coat it with the cinnamon sugar.
In a mixer fitted with a paddle attachment, cream the butter until smooth. With the mixer running, slowly add the sugar and mix. Add the eggs and mix until the mixture is light and fluffy. Sift the sifted flour, baking soda, baking powder, and salt together. Working in batches, add them to the butter-sugar mixture, alternating with dollops of sour cream. Pour the batter into the prepared pan.
Make the topping: In a medium bowl, combine the brown sugar, flour, and cinnamon. Add the butter and, using your fingertips, pinch the ingredients together into a sandy, crumbly mixture. Add the pecans and mix. Sprinkle the mixture over the cake.
Bake until risen and browned, about 35 to 40 minutes. Let cool in the pan then turn out. Serve in slices.