Hi,MJ21193 an 21194 from ON semiconductors are an excellent choice, but must change on both channel
If they are TO3 type 2N3055 and MJE2955 will work well. If another case look at the TIP range.
Very good! Looking at DS, these are much better/safer than those from ON's MJ21193/4 to use in the AU-919Hello,
I have used the transistors 2ST2121 and 2ST5949 for my Sansui AU919.
The case is TO3 and ft is high. 2ST2121 and 2ST5949 are obsolet, but Mouser has still types in stock.
You can use 2SA1837 and 2SC4793 as drivers (on the small heatsinks on the power amp PCB) but you will need to modify them by grinding off the integrated heatsink insulation (these are completely plastic insulated) to expose the heatsink tab metal and use standard mica insulator, and using the middle lead (collector) instead of the heatsink tab as a contact. This MUST be done or the bias thermal tracking is not going to work properly. This is a bit of a complication but unfortunately anything else I could recommend as replacements is not guaranteed not to be fake.