Yeah, this video didn't make much sense. It's quite sloppy, in fact.
The data presented show what the presenter calls a very smooth frequency response. In fact, when the grills are placed on the speakers, the little "hump" at 4k also disappears. The presenter, however, fails to state what Harbeth states clearly and repeatedly: their speakers are designed to be used with the grills on. This is noted in most reviews and on the Harbeth site (
https://harbeth.co.uk/userguide/ ).
When the presenter displays the off-axis response curves, the little 4k hump is back. It appears to be that the measurements were made with the grills off, even though the presenter has already shown the data (but omitted the manufacturer's statements) regarding better measurements when the grills are left on as designed.
This sloppiness appears to be repeated in the spectral display plot: the woofer's range is noted to be "really smooth" but the 4k hump has reappeared here as well ("a little bit of stored energy from that peak…but it's not bad; not bad at all").
It very much appears that even after confirming what Harbeth clearly states, the measurements were made without the grills installed. And even then the little 4k is "not bad; not bad at all."
Why not do the measurements with the grills on when they work best that way (and when the manufacturer states that is how they are designed to be used)?
But then the video dives off the cliff into full woo woo. "It measures so well, why not go in and try to upgrade the parts quality?" Huh?
After criticizing Harbeth for designing a crossover that is very successful in smoothing out the response, the presenter criticizes the lack of space for putting different parts in the tiny speaker. I doubt that the manufacturer had "leave room in the cabinet for user-installed parts swapping" as a design goal, but nevertheless the presenter finds fault here.
And then the most amazing statement is made: the presenter states that the cabinets are designed to have a resonance and "have a little bloom down in that lower vocal region." Didn't we just look at a spectral decay and a frequency response that was described as really smooth in the woofer's range with only a 4k bump when measured (against the intended design) with the grills off? Where is this supposed bloom? What's the point of doing measurements if they are ignored two minutes later?
So, measurements are done that show very good performance and then the measurements are ignored and without even listening to the speaker a "bloom in the lower vocal region" is declared and the speaker is criticized because the type of parts used is, without a shred of evidence, declared "cheesy."
It may be that a bloom is audible that doesn't show up in the measurements. It may be that using different parts here, there, or everywhere would improve something in the sound (measured or audible). None of this is evaluated by listening or supported by any measurement. Consistent with the clickbait video title, the end result is sensationalist hot air.
Most boutique manufacturers try to build their reputations by making products that sound good and measure well. It's a shame to see the low road taken where the dominant approach is to attack and say "other people's stuff is crummy," especially when the observations (measurements or listening) don't support such claims.