What if a high end speaker measures really badly?

Narrow-band peaks and dips which occur within about 1/3 octave of one another tend to be "averaged" by the ear. Therefore, that on-axis frequency response graph looks far worse to the eyes than it sounds to the ears.

The on-axis dip at 3 kHz is wide enough to survive the ear's "averaging" characteristic, BUT it corresponds with an off-axis rise in that region.  So my guess is the designer put a dip at the bottom end of the tweeter’s range to compensate for an off-axis "flare". Imo this is a good design choice.

The on-axis emphasis centered around 11 kHz can be compensated for by listening off-axis.

In fact, it looks to me like at about maybe 10-20 degrees off-axis the 3 kHz dip fills in and the 11 kHz bump smooths out.

My guess is that this speaker would sound excellent with proper set-up.

Duke

Not an Alta Audio dealer

@soix has it right. The Alta Audio speakers should be listened to before buying. I was one of those commenting on the Alyssa thread about frequency response and discontinuity issues. There were three speakers from them represented at Axpona. I heard the same issue on all of them. After the show, I wanted to see if there were measurements out there showing what I heard. Stereophile measurements of the Adam and Alyssa clearly show issues at around 3k, and to me it is audible. I wanted to like them, because they look beautiful. Some people may like the sound that they produce, I did not. 

Well then it better sound good.

I turned my laptop speakers up all the way and I still can't hear that graph. So no comment.

Probably not myself personally, but If someone likes the sound of an expensive speaker it does not matter that it does not measure well or technically may be poorly designed or implemented. The off base measurements will probably be an indicator of the particular unique sound that is liked and is less likely to be found elsewhere. In other words a poorly engineered speaker may sound unique and distinguish itself from others but the reason it sounds that way may not be a very good one.

Or one may just be drawn to a product by aesthetics.  You have to live with your speakers so looks matter.  It’s all good even if not so much technically.