I work for a company that makes flexible heating elements, and most of our products are essentially the same thing as those diaphragms, and those in EMITs and EMIMs (though our products are heaters, so the foils and trace widths used are deliberately high resistance). Most of our heaters are made on Kapton, which is what the Infinites are, but I am not sure what material GAS used. Kapton has the merit of very high heat tolerance, which is why it is also used for voice coil formers.
I tried to interest them in making replacement diaphragms for the Infinities, but absent an actual order, they weren't interested. And they may have been right because soon later, a guy started offering replacement diaphragms - his company's name was AVA (which I associated with Audio by Van Alstine, but there was no relation). After several years, the company seems to have disappeared, so demand may not have been great enough to sustain production (Correction - as posted below, AVA is still in business, so my statements are incorrect. My apologies) We actually have the capability of making very long heaters, and those GAS diaphragms seem quite long - wonder who made them.
