I have some NOS RFT/Seimans, labeled Brinmar, made in East Germany...farmed out from Siemens, perhaps in the 70s ...as I read up on the MB 450, I am thinking that these are different tubes. Aren't the MB 450s made in Germany...

From cursory surfing, I thought the 470 was different from the 450 also...definitely a lot cheaper. If you get good information on the tubes or try them, please let us know your impressions. They sound interesting.