@mozartfan,
''Here on YT , I am not sure where the tech geek is placing the foam?''
The foam is glued inside to the back cover of the compression driver. Also, the titanium diaphragm is coated with aquaplas for damping resonance, within the diaphragm. See the link below for a well engineered titanium compression driver.
https://www.hifido.co.jp/sold/14-81603-12031-00.html?LNG=E
''Here on YT , I am not sure where the tech geek is placing the foam?''
The foam is glued inside to the back cover of the compression driver. Also, the titanium diaphragm is coated with aquaplas for damping resonance, within the diaphragm. See the link below for a well engineered titanium compression driver.
https://www.hifido.co.jp/sold/14-81603-12031-00.html?LNG=E