Von Schweikert also uses it. From their website...
Due to new developments in transducer design, VSA has announced a highly improved version of their classic VR-4 Gen III model. The new Special Edition model utilizes a new dual-ring radiator, an extraordinary breakthrough in tweeter technology from Denmark. This new "dual-ring" design eliminates the tradeoff between low mass and rigidity, i.e., the problematical diaphragm flex causing distortion. This new tweeter operates from 500Hz to 40,000 cycles per second, with negligible distortion. In fact, it sounds more like a ribbon than a dome tweeter, but power handling and dispersion characteristics are state-of-the-art, correcting the problems found in flimsy ribbons. Although it is trite to say that this new tweeter will allow you to hear things in your recordings that you have never noticed, that is the only way to properly describe the sensation of hearing the Special Edition for the first time! Clarity is achieved not by excess treble energy or amplification of harmonics, but by dramatic reduction in distortion and phase shift.
Due to new developments in transducer design, VSA has announced a highly improved version of their classic VR-4 Gen III model. The new Special Edition model utilizes a new dual-ring radiator, an extraordinary breakthrough in tweeter technology from Denmark. This new "dual-ring" design eliminates the tradeoff between low mass and rigidity, i.e., the problematical diaphragm flex causing distortion. This new tweeter operates from 500Hz to 40,000 cycles per second, with negligible distortion. In fact, it sounds more like a ribbon than a dome tweeter, but power handling and dispersion characteristics are state-of-the-art, correcting the problems found in flimsy ribbons. Although it is trite to say that this new tweeter will allow you to hear things in your recordings that you have never noticed, that is the only way to properly describe the sensation of hearing the Special Edition for the first time! Clarity is achieved not by excess treble energy or amplification of harmonics, but by dramatic reduction in distortion and phase shift.