The 6.5" is NOT yet available... just testing the sample. Very smooth measured response on these... can cross as high as 4-5k for tweeters that don't like much mid-range output. Measured open baffle -- in a baffle low-end would increase on all of them but you can see the trend as the very deepest bottom end increases as you go up in size and the top-end increases as you go down in size.