Except on this amplifier brand I haven't see the 2N3055 and 2N3055H from Sanken - go also to the images under
https://marantzhallo-fi.blogspot.com/2015/05/bedini-2525-class-power-amplifier.html
Maybe made exclusively by Sanken just for this manufacturer.
The only manufacturer I often see from Japan in various vintage amplifiers is Toshiba - go to the attachments.
But RCA (the brand that was the first to release the 2N3055) was most likely counterfeit even back then - see the different appearance of the typefaces from the attached images.
https://marantzhallo-fi.blogspot.com/2015/05/bedini-2525-class-power-amplifier.html
Maybe made exclusively by Sanken just for this manufacturer.
The only manufacturer I often see from Japan in various vintage amplifiers is Toshiba - go to the attachments.
But RCA (the brand that was the first to release the 2N3055) was most likely counterfeit even back then - see the different appearance of the typefaces from the attached images.
Attachments
The Sanken ”H” types may or may not have been Hometaxial. I don’t know if they had a single diffused process - but they had several that are pretty damn rugged. Toshiba did have a single-diffused process, used on types like the 2SD111. In either case they probably did meet the 2N3055H spec for ruggedness. Toshiba did also make 2N3055’s and 2N3773’s using their triple diffused multi emitter process, and had corresponding 2S numbers for them. Their old 2SD424 would pass the RCA 2N6259 2.5A/100V/1 second ruggedness test, even though the data sheet showed a second breakdown breakpoint of 70 volts. So you know they could make something as good as a 3055H or 3773.
