Waterfall's are very pretty. But they require you to choose between time/domain/amplitude resolution, can't have them all simultaneously. In other words, you can make them look like whatever you want. You can see how narrow the amplitude is set, so while the bumps are highly suppressed, they are still there. And even Stereophiles low res 1/6 octave measurements have spikes all over the place, in-room. But those are also loudness graphs which are weighted differently than SPL. The NRC measurements are a higher resolution which serves to make the offending frequencies more clear(jagged spike vs broad hump)
If diffraction was the issue, what obstacles are the sound waves coming in contact with 0 through 75deg off axis at all those frequencies? Only the high Q resonance at 2khz is likely diffraction resulting from the coaxial design, and a low crossover frequency that shows a rise in amplitude resulting from differing driver sensitivities. The low overall sensitivity probably explains the crossover choice as the woofer wouldn't have been able to keep up with the tweeter if asked to cover a broader frequency range.
Just to show my perspective, I've been studying the work of Harman/Toole/Olive/Welti/Devantier and realize that the subjective preferences listeners have can be explained in the speakers' frequency response. It's 2017, we know how to measure all of these things, and the hundreds if not thousands of double blind tests performed at Harman confirm that we can predict listener preference with sufficient measurements (70). We as consumers should be DEMANDING comprehensive measurements from every manufacturer. Those KEF's are $1500 and can't maintain +/- 3dB.
Again, it's 2017, and yes the JBL M2 is a top of the line speaker, but many others are capable of reaching a +/- 1 dB threshold as well. I do not purposely pick on KEF here, it's only that I was able to listen to that speaker on several different days and kept coming away with the same impression. A conversation with an engineer is how I found the Soundstage measurements. The correlation between those measurements and what I was hearing compared to 3 other speakers was obvious.
Personally, I feel the Phil 3's ribbons compress too much for movie sfx and are outperformed by beryllium - side by side test with a Focal monitor with inverted dome(highly subjective, me just wanting the best of the best). So, Dennis, I'll be putting your speakers through CTA2034 this fall, actually, so I can design a well paired center channel. If I can get my hands on a single AA, I'll run that too. I really think you are gifted with a true 'golden ear' and your designs will easily meet a +/- 3db threshold. But I need the measurements because I do not have your talent!
Please note I'm taking those measurements solely for my purposes, but I will be happy to share the data with you, privately. The only measurements I'll be posting in the future will be the response of my room after I complete a major overhaul.
Thank you for the thread jack!
