Ok Jerry,

Found a spin I did on the Sierra-2, went back in and adjusted the bass expansion point so that it matches what we currently use so this is a very fair comparison. (curves are adjusted to match sensitivity)

s2EXv2 vs S2.png

You will note Sierra-2EXV2 has quite a bit more energy in the range of 55Hz to about 120Hz. EXV2 also has more energy in the range from about 40Hz and lower, with the lower the frequency, the more output. Keep in mind there is nearly 6dB more output at 20Hz, which is 4 times the output, and 4dB more output at 70Hz (more than double the output)

This is a good example of what I tried to describe to you regarding different bass roll off slopes and Q. If we were to simply rate either of these speakers using F3, F3 on Sierra-2 = 54Hz, Sierra-2EXV2 = 48Hz. Which makes them fairly close spec wise, but as you can see from the actual measurements, they aren't close at all as both the Q and roll off slope for the Sierra-2EXv2 is quite a bit different.