Is it possible to use other drivers for the NFX? I do have different vintage 8" og 9" inch "nearly" fullrange drivers which do sound fine in OB speakers, with a added tweeter and woofer, but I would like to have a more narrow speaker, which gives much of the OB sound, but without the need for a added woofer. I was thinking more of a 8/9" inch with a tweeter on a removable front plate. Part of it testing different drivers.

I really like the praise from the speakers page: "The result is simply the most non-congested sounding cabinet you've ever heard next to an open baffle." But is it true?

Hello Mellemhjulet,
I hope someone who has this NFX speaker will see your post and reply.  I am not sure any of the forum members who built this speaker when it was introduced are still here.  Except Steve Deckert of course.  

This is the Decware speaker which is most appealing to me.  I look forward to hearing your report if you build a pair.  

I do not know to what extent it is successful with other 8 inch drivers.  I would guess it would work well. At least I do not see why not.  

Best wishes for your build, Brian