I do love a deep dive and a bit of detective work. Over at Musings of a Watch Addict, we have a superb example of both where the author traces Seiko’s ‘new’ 6L35 calibre as introduced in the SJE073:
I’m fine with all these except for 1 thing, this is not a completely new caliber from Seiko Japan. In fact, it was first introduced way back in 2007 as the 4L25 and was finally discontinued in 2013 as the 4L75, before being resurrected in 2018 here as the 6L35.
S/he (author is anonymous as per their about page) does a very deep dive that I cannot recommend enough, and from it surmises that Seiko, to my surprise, is the source of the Soprod A10 calibre!
Not surprising, Seiko did succeed to some extent in this as it was thought that Soprod eventually licensed this design from Seiko and produced the Soprod A-10 caliber from this base caliber. Note that neither company have ever acknowledge who really designed the movement and who licensed it.
Well, that’s interesting. Here’s a picture of the A10, as seen in my OWC 6538:
Who actually does the hard work of designing movements, where they are made and such are typically among the least disclosed bits of information, so this is a welcome ray of sunshine and well worth your time.
ultracrepidarian 