Preheat the oven to 400°F. Lightly grease (or line with parchment) a large baking sheet.
Pulse together the flour, baking powder, baking soda, salt, sugar and pecans in the bowl of a food processor. Add butter, and pulse until the mixture is the texture of coarse meal.
Add cream and pulse until a shaggy dough results. Add enough ice water to bring the dough together in a cohesive mass.
Gather the dough into a ball, and place it on a well-floured work surface Pat/roll it into an 8″ to 9″ circle about 3/4″ thick. Sprinkle with turbinado sugar. Use a 2″ cutter to cut about 18 scones, gathering the scraps and gently shaping into round scones without re-rolling.
Place the scones on the prepared baking sheet, leaving just over 1″ between them. Bake the scones for about 20 minutes, until they’re golden brown.
