I had decided to bow out of the conversation. When a person starts with telling me I am presuming a lot of things when all I am trying to do is get honest information, it is time for the conversation to end. But, let's try to answer your question.
There is no "bass bump" in the Sound Power Curve - the bass region has pretty much the same curve in the SPC and Listening window chart. What the SPC shows is an expected roll off in the SPC with a front firing set of speakers.
Thanks Craig. Interestingly enough I *did* see a bump in the sound power curve - going up at least 3dB between 150 Hz and 80 Hz - and didn't see a comparable bump in the Listening Window curve. I had figured that was coming mostly from the rear ports but that's just a guess.
BTW I'm looking at the frequency graph for non-powered M100's in case we're looking at different graphs.
Agree this is a long topic to discuss, but it's fun
Go take another look - you will see the two lines converge at 100 Hz - then the SP curve starts slowly dropping, as one would expect, as the frequency rises. Both curves have almost identical "bumps and shallow valleys" out to 15,000 Hz.
What may look like a "bass bump" is actually the slow decline as frequencies rise, as we expect, above 100 Hz. The shape of the LW and SP curve are the same, outside that slow decline.
At and below 100 hz, the 6.5 inch drivers would be almost spherical in response. Think about subwoofers - most are not "locateable" in a room below 100 Hz. The 6.5's act as a "point source" below 100 Hz, which is why the LW and SP curves are so close in the 30-100 Hz range.
