http://www.adam-audio.com/en/technology/x-art
http://www.enjoythemusic.com/magazine/e ... n_tlr1.htm
(scroll down for freq response)
en.wikipedia.org/wiki/TweeterSuper tweeter
From Wikipedia, the free encyclopedia
A super tweeter is a speaker driver intended to produce ultra high frequencies in a multi-driver loudspeaker system. Its purpose is to recreate a more realistic sound field, often characterized as "airy-ness". Super tweeters are sometimes found in high fidelity speaker systems and sometimes even in home theater systems. They are used to supplement the sound of tweeters by reproducing frequencies which the tweeter may produce only with a narrow polar output, or perhaps with distortion.
An early example of a super tweeter used in a commercial design is the microphone element derived 4001 from STC, used in the Bowers & Wilkins DM3 and several subsequent models. These were basically two-way designs using the STC 4001 as a super tweeter. Ohm, the Brooklyn-based speaker manufacturer, uses super tweeters in their Walsh and MicroWalsh speaker lines, which several reviewers have concluded offer a more pristine high-end response.[citation needed]
A super tweeter is generally intended to respond well into ultrasonic frequencies over 20 kHz, the commonly accepted upper frequency limit of human hearing. One super tweeter has been designed to respond up to 100 kHz.[1] This super tweeter was designed to eliminate the problem of the normal tweeter diaphragm continuing to move after a signal has ceased.
AMT tweeter
The Air Motion Transformer tweeter works by pushing air out perpendicularly from the pleated diaphragm. Its diaphragm is the folded pleats of film (typically PET film) around aluminium struts held in a strong magnetic field. In past decades, ESS of California produced a series of hybrid loudspeakers using such tweeters, along with conventional woofers, referring to them as Heil transducers after their inventor, Oskar Heil. They are capable of considerable output levels and are rather more sturdy than electrostatics or ribbons, but have similar low-mass moving elements.
Most of the current AMT drivers in use today are similar in efficiency and frequency response to the original Oskar Heil designs of the 1970s.