I have spotted the following cartridge US patents from Denon (in each various names) at https://www.freepatentsonline.com/
US3084228A (04/22/1960) Piezo
US3360616A (06/25/1963) Ribbon
US4161631 (07/13/1978) MC1
US4488284 (09/30/1982) MC2
US4455639 (08/22/1983) MC3
US3627931 (01/23/1968) MM1
US4209669 (12/21/1978) MM2
I haven’t found an MC patent preceding the manufacturing of the DL-103.
DL-103 was designed/assembled in 1965 for radio broadcasting studios. https://www.denon.jp/ja-jp/museum/products/dl103_2.html
It was commercialized in 1970.
Denon Museum lists thirteen DL-103 models from 1969 to 1994
https://www.denon.jp/ja-jp/museum/index.html
(only to test Bill's reflexes
)
George
US3084228A (04/22/1960) Piezo
US3360616A (06/25/1963) Ribbon
US4161631 (07/13/1978) MC1
US4488284 (09/30/1982) MC2
US4455639 (08/22/1983) MC3
US3627931 (01/23/1968) MM1
US4209669 (12/21/1978) MM2
I haven’t found an MC patent preceding the manufacturing of the DL-103.
DL-103 was designed/assembled in 1965 for radio broadcasting studios. https://www.denon.jp/ja-jp/museum/products/dl103_2.html
It was commercialized in 1970.
Denon Museum lists thirteen DL-103 models from 1969 to 1994
https://www.denon.jp/ja-jp/museum/index.html
(only to test Bill's reflexes
George