Joe,
Here's a link to a lot of information regarding Siemens tubes:
http://db.audioasylum.com/cgi/search.mpl?forum=tubes&searchtext=siemens+rohre
Here's a link to a lot of information regarding Siemens tubes:
http://db.audioasylum.com/cgi/search.mpl?forum=tubes&searchtext=siemens+rohre