What amplifier you're feeding them with?
Since I mentioned I was doing a crossover mod (in response to some requests on the AVS forum), I did complete one and to my eyes and ears it improved the sound significantly. Basically, I brought down the 700 Hz bump and changed the tweeter topology to keep the the treble in line with the new midrange level while retaining as many components as possible from the stock BOM. I found the stock sound somewhat blurred in the midrange due to the woofer peak and the resulting obscuring of detail in the lower treble. The mod requires the purchase of a $6-$7 2.0 mH steel laminate inductor and a couple of resistors.
This is really weird. So both speakers in the pair measure the same? Where are you located?
Stuff like this isn't supposed to happen. We're going to figure this out. Here's how my tweeter measures with no crossover in line--it's the raw response. Is this how yours measures with no crossover?
I have not followed this thread closely but the phase of the C-note is negative at high freqs. Speakers with this don't do well with Class D amps without PFFB and will result in peaking at high frequencies. I'm not sure I am on target with that applying here but thought I would offer it.
audiosciencereview.com
I took this awhile back when I first noticed the issue, it's the tweeter raw, then with the xover hooked up. It's all I have at the moment but I can take a new one if need be.
What amplifier are you using? Can you measure the freq response of the amplifier output voltage when driving the (assembed with crossovers) C-Notes?
Do you have a Class AB amplifier available to try with the C-Notes? I do think you are seeing peaking caused by Class D without post filter feedback, into a load with negative phase at high frequencies. I copied @pma 's curve with Aiyima A07 (thread linked in my previous post) into his dummy load, which looks similar to what you are seeing with your setup.
Does a friend have an old AB amp of any sort? It doesn't have to be fancy.
I wonder if you can tame the peak with a shunt (RC) across the amplifier or speaker terminals. Not ideal but possibly it would help. @pma have you tried this? Top image without shunt, bottom model with shunt (with 80dB flat speaker response to just show the filter effects). The component values are guesswork since I don't know what values are inside the amplifier. Maybe @pma knows. I wouldn't do this until someone who knows this stuff better offers an opinion whether it is OK to try it.
Paging @Dennis Murphy - the world waits with bated breath for your crossover mod!
There are probably a lot of other subjects more worthy of bated breath. I'll have to revisit this. I don't remember how much my mod improved things. I'll fire up the stock and modded version tomorrow and see whether it's worth the hassle.
