tobymcwilliams, where do you live? I have a "Daniel Lesueur", who worked next door to Friederich in the 70s and 80s. You will find sound examples on youtube. Send me a message if this is of interest to you.
1964 - Masaru Kohno
1967 - Masaru Kohno
1989 - Antonio Marin Montero
2017 - Tobias Braun
Feel free to ask me anything about Japanese classical guitars.