I fail to understand your logic. The whole purpose of this thread was to help readers understand the frequency response of speakers/subwoofers as reported by manufacturers. The reason I showed the frequency diagrams for both +/- 3dB and +/- 6dB is to demonstrate that even though the frequency response of a speaker is exactly the same, the numbers can look different depending on the +/- dB levels that the manufacturer uses. In the example that I used, the frequency response of the speaker can be reported as:
56.5Hz – 12,500Hz, +/-3dB
or
40.0Hz – 16,500Hz, +/-6dB
Obviously, the +/-6dB frequency response looks more impressive, but that is misleading.
There are some manufacturers that go to the extreme and state in their literature that the frequency response of their speaker/subwoofer is 25Hz @ -10dB.