These were all made at the Primo Factory...but I'm sure the various companies specified slight changes...
There were versions by JVC, Nakamichi, Tascam & Teac similar to the old Nak CM100-CM300...all capsules should be interchangeable...
I don't know much about the CM-50 line
You can still get a NEW Nak Clone from PRIMO in Japan...search the old Team Nakamichi threads...