As Bifwynne indicated we had a very good discussion on 1st-order x-over speakers in the "Sloped Baffle" thread sometime back in July 2014. A cut & paste from that thread (which was in response to Bifwynne asking me which were the 1st order x-over speaker brands in the market in a very similar vein as you have in this thread):
07-05-14: Bombaywalla
Bifwynne, yes, I think you have the list.
Single-driver speakers are also time coherent (since they dont have a x-over to begin with) but they might not have the freq range extension you are looking for.
Some of the latest generation Martin-Logans might also be time-coherent (they claim to have made big strides in integrating their woofer with their ESL panel) & the full-range CLX.
Quad speakers are also time-coherent such as the ESL-2085 & they might other models (ESL-989?)
Another brand is Eminent Technology LFT 8. They might have a latter rev of this model, not sure.
Yet another brand would be Sanders Sound Systems 10C & 11 ESLs. You'll find measurements of the Innersound Kaya & Eros Mk3 speakers on Stereophile if you search. Innersound speakers were basically made by the same person who owns Sanders Sound Systems today. I realize that I'm extrapolating since Innersound Kayas were time-coherent that Sanders Sound Systems 10C/11 will also be. This is based on a reasonable assumption that the same designer has not changed his philosophy when he started his new company. Atleast I did not get this impression when I spoke to him in Dec 2013/Jan 2014.
I'm almost willing to say that SoundLab ESLs are also time-coherent but I might be wrong here. Not sure.
That's all I can think of right now. If I think of more brands/models I shall post. Thanks.
Bombaywalla
and in that same thread Unsound listed the following:
07-20-14: Unsound
I just remembered the name of the old poster that started a time coherent speaker company; Karl Shuemann. To be fair to all here's a list of those companies that have made time coherent speakers that I'm aware; of starting with Karl's (which fortuitously falls into alphabetical order):
Audiomachina
Dunlavy
Greenmountain
Meadowlark
Quad
Thiel
Vandersteen
thanks.