It is old CBA, certainly from 40's maybe even older but certainly not from 60's. My first accordion teacher had Weltmeister from 30's or 40's which has brass reeds, it was quite heavy instrument. When I first tried CBA it was C system Firoti from some era. Picture isn't very good but I managed to find similar Royal Standard PA's from net. Some were sold on eBay. If I see correctly(?) it has seven bass rows, 140 basses.
One thing is sure, if You wish to play it it needs some work. I believe that its overall quality is quite good, similar to Hohner's from same era. Later East-German instruments were produced from cheaper materials and I haven't seen any later model with pearl/celluloid buttons/keys, of course instruments themselves were coated with celluloid, but buttons/keys were made from some weird and soft plastic. We call this plastic "hapupiima plastik" in estonia, it means sour milk plastic in english
It was called it because keys weared very easily and were very soft and prone to break.
UPDATE: It may sound something similar to this https://www.youtube.com/watch?v=u1v898gXmPs
or this https://www.youtube.com/watch?v=5hbzR0KhJes