Headphones

Most headphone drive unit diaphragms are formed from some type of plastic. Mylar (the tradename name for a biaxially-oriented polyethylene terephthalate) is popular, although some manufacturers have chosen superior alternatives like PEEK (polyether ether ketone) in search of improved physical properties. Plastics can’t match the stiffness achieved with an aluminium or, still better, beryllium diaphragm but plastics have higher internal losses (which improves the damping of bending resonances when they occur) and are inherently suited to the traditional dome-plus-annulus construction of headphone drivers. French brand Focal’s aluminium and beryllium units, by contrast, are constructed like miniature loudspeaker drive units. One means of improving the stiffness of plastic is to coat it in a thin layer of electroplated or vapour-deposited metal. Titanium is one option and Audio-Technica uses tungsten in its ADX5000. How effective are such coatings? Manufacturers, in my experience, never put figures to it...