J!m
Veteran and General Yakker
KR is the predecessor of SA. That Nakamichi was pretty cool, the idea was to flip the cassette instead of reversing direction so the heads would keep better alignment. A novel idea.
the KR is a true chromium tape, and it used the (3M?) pigment which the Japanese were not happy about. So, to avoid paying for pigment, they developed cobalt doped ferrite in such a way (I forget what they called it) to produce the “super avalyn” particle, hence the SA designation.
after the first improvement in 1983 or so, it remained quite true to the end. (Color got darker too) So my 1984 tapes bias nearly identically to 1994 tapes. Quite uncanny and I never tried swapping the tapes into the other shell to do if then they’d have the same difference... (probably not)