beryllium vs diamond

georgehifi, it is not a matter of opinion. That ESLs are better is a matter of fact for the reasons I stated above.  I love Maggies but they can not hold a candle to a big ESL. 

The N28-BER by Transducer Labs that Fritz uses in his Carrera speaker is the only one I've heard that I think I could live with.  BTW, TL describes this on their website as pure beryllium.

I have no experience with diamond tweeters, however I recently picked up a pair of second hand  Focal Electra 1008 BE speakers and am using them in a near field setup in my computer room, driven by my Audio Research VSI 55 integrated and they sound fantastic.  I don't care for "bright" speakers and the Focals are not to my ears.  They are very detailed, but the top end doesn't call undue attention to itself.  I don't play them super loud, but have tried them out in my main system and in many ways they bested my Legacy Audio Focus 20/20's, but they are too small for that large of a room.

There are some "reviews" (sales pitches) on Upscale Audio's youtube channel on a couple of the Focal speakers that use the BE tweeters.  You might get more technical info from those.

kosst_amojan"Big panels are some of the most unnatural speakers I've ever heard. They sound interesting, no doubt, but almost no natural sound source is a gigantic flat membrane."

This reflects, indicates, and displays a profound, substantial, and significant misunderstanding, confusion, and/or ignorance/unfamiliarity with the design, substance, and nature of speakers intended for Music Reproduction Systems. For one thing no instrument in an orchestra, band, or ensemble resembles a cone speaker yet that would be your alternative to a panel speaker also depending on the design, construction, and technology employed in the panel speaker there may be substantial benefits and advantages in terms of crossover design and implementation that can easily render the panel speaker to be the objectively and measureably superior speaker but of course if you're experience is limited to just a few designs you may suffer from the type of misconception and misunderstanding as stated hear.