Honestly not really that much more.Likely need to turn the NHT up on volume a bit more?
Owned various pairs myself over the years and have a fondness for them. Loved the Classic 3’s.
This updated model uses bespoke drivers. The voice coil on the new woofer is much larger than the original.It's the Acoustic Research DNA within the bass/mid driver and acoustic reflex design (the founder of NHT worked for AR early on in his career).
I've a minty pair of Model One here, as well as ELA mk 1.25 and, as you say, the NHTs are no slouch.
I would suspect that the primary difference between these and the original driver (at lease the magnetically shielded version) is that the foam surround has been replaced using a butyl rubber one. Acoustic suspension requires both a looser driver suspension and, typically, a weaker motor (smaller VC and magnet), such that the restorative 'spring' of the trapped air within the small enclosure dominates. For his original prototype, Villchur took a standard 12" Western Electric driver and cut strips out of the spider, and replaced the doped pleated fabric surround with a half-roll surround made from mattress foam sheeting. This was then installed into a tiny (for the day) 1.7cu. ft. sealed box with cheesecloth bagged Fibreglas(tm) insulation within. His further experiments showed that he could reduce both driver size and motor 'power' and still achieve bass down to 40Hz in small boxes.This updated model uses bespoke drivers. The voice coil on the new woofer is much larger than the original.
I forget all about the hidden leads. Honestly at about $350 new I can't imagine a heck of a lot of other speakers that are so good. Heck even at post covid prices I still think they hold up.Best not to confuse dust cap size with voice coil diameter. Those are likely as not just covering the VC leads of old. Of course, NHT could easily have increased power handling relative to previous, although this can be down to factors other than strictly coil size, even changing the tweeter slope from 2nd (12dB/octave) to 3rd order (18dB/octave) without changing the crossover point can allow for a higher power handling rating of the system as a whole (it appears that NHT changed to 3rd order HP and lowered the crossover frequency relative to previous).
Regardless, all of the small enclosure 6.5" bass/mid NHT models that I've heard were rather good sounding. In fact, I'd say they were difficult to beat for the asking prices (especially so, early on when compared to the UK imports of similar dimensions/pretentions).
Early NHT SuperOne pictured below. Those Tonegen tweeters did like to shed their doping, hence the dirty brass metal dome look. It appears that the 2.1 in your pictured have polymer domes in, which should fare better.
Eden Audio sell them in the UK
It isn't surprising that some of the smaller NHT sound like old AR models, as Ken Kantor started out working for AR. He shares credit for the design the AR 'Magic Speaker', a very big box with way too many drivers in, making design of a small infinite baffle 2-way seem a piece of piss by comparison. ISTR, Kantor having mentioned in an interview that the bass/mid of the original NHT Model One came from AR. This was a foam surround paper 6.5" that certainly looked the part.Heard a pair of these recently - shocked how good they are. I preferred them to Neat Petite Classics !! Balanced and engaging - very similar to my old AR18s, my new favourite real world speaker !
I bought mine off amazon. They also sell directly off their website. I have not heard the SuperZero.
Someone actually compared them to their ProAc speakers. They said they hold a candle to their Response D2.Absolutely.. they look interesting and a cheaper alternative to Atc