Heat oven to 350 degrees. Grease and flour large Bundt or tube pan. Sift flour, soda, and salt together; set aside. Cream butter and sugar. Add eggs, one at a time, beating well after each addition. Add vanilla. Add sifted dry ingredients alternatively with buttermilk, beginning and ending with dry ingredients. Beat only until combined. Pour batter into prepared pan. Bake in preheated oven for 50-70 minutes, or until cake tests done. (Baking time will depend on size of pan and humidity levels.) Let cake stand in pan 15 minutes before inverting onto wire rack to cool.