Which Tweeter preferred- dome natural material, Beryllium/Metal or Planar Ribbon? Why?

For me its all about fatigue. I've built a few speakers and the metals don't work for me. Recently tried the Scanspeak Illuminator and they were very nice. The 2608 was a bit lifeless. The Dynaudio D28/2 and the D260 are my favorites and I could listen to all day. I have not heard a good ribbon and would like to try that soon. Would pair it with some oider Dynaudio 17W75s or a Scanspeak 4531. You all already gave me some ideas - thanks.

Kapton for ribbon midranges and tweeters for higher power handling, but not quite as smooth as mylar. Aluminum for cylindrical tweeters and midranges seem less harsh sounding than titanium. I've not tried beryllium so no opinion but some swear by beryllium.

@chorus , mass and surface area are minor issues in comparison to this. True ribbons are like ESLs, a force over area drive system. Every molecule of the ribbon is controlled by the electrical signal. Dynamic speakers use a voice coil to drive a diaphragm. The diaphragm is expected to follow the movement of the voice coil perfectly. It is not controlled directly by the signal. It adds an uncontrolled resonating mass to the drive. The end result is significantly more distortion. By making a long ribbon ala Magnepan you can form a line source which is very difficult to do with dynamic drivers. Many have tried and failed. Line source speakers have significant advantages over point source speakers. There is one problem with ribbons. They can be rather fragile. 

Although I have not personally heard them, I suspect the Voxative AC Xp Field Coil to be one of or perhaps is the best based upon reviews/reports.  Unfortunately they’re very expensive.  Hearing them is on my bucket list.  

@arion ,

Come to the Midwest. I would love to hear your dipoles!

All the best!

JD