I was happy to receive a reply to my questions about the new Tesla models from the designer of the Beyerdynamic T1, Gunter Weidemann (see http://www.stereophile.com/content/geek-talk-beyerdynamic-t1-designer-gunter-weidermann ) a couple of hours ago...
Q: From pictures, it appears that the new micro velour/gel earpads of the forthcoming T70/T70p could be installed on previous versions in the DT770/DT880/DT990 series - can you confirm if this is true?
Mr. Weidemann: The new T 70 earpads will fit the DT 770 housing in a mechanical way, but will change the DT 770´s frequency response. As the T 70 is a closed headphone, the T 70 earpads are closed either. However, DT 880 and DT 990 need open earpads, as these are semi-open/open headphones. Thus the T 70 earpads cannot be used for DT 880 and DT 990.
Q: The T70/T70p appears to be an upgraded DT770 - are there any future plans to release a T80/T80p (semi-open) or T90/T90p (open)?
Mr. Weidemann: The T 70 is a unique model to fill the gap between DT 770 and T 5 p.