Wow the 10K uF 85V caps look "custom made" it may be difficult to find any rated at 85V unless you want to pay for it try digikey.
Adding a fouth output pair is not advised because it wil not give more power because the rail power voltage is still the same.Generally you would need to increase the rail voltage but technically the load will be shared by a 4th member but then the driver stage may need to upgrade (reengineer again,I don't think we should fool around with it ).It's not easy to give a one sentence answer.
On paper the 2sc5359/2sa1987 are rated 180W collector current vs 150W 2sa1302/2cs3281.All other details are similar right down to characteristics curves.Yes you can substitute and it would be interesting to hear the difference in performance if you have the money for 6 pairs. 😀
2SC5359
Becareful about the mica insulators type when you remove transistors,the mica can break or a slice of it will come off.Silicone impregnated type is easier to use although they don't need silicone grease it's good to apply but make sure it's neat no extra grease around the leads.
Adding a fouth output pair is not advised because it wil not give more power because the rail power voltage is still the same.Generally you would need to increase the rail voltage but technically the load will be shared by a 4th member but then the driver stage may need to upgrade (reengineer again,I don't think we should fool around with it ).It's not easy to give a one sentence answer.
On paper the 2sc5359/2sa1987 are rated 180W collector current vs 150W 2sa1302/2cs3281.All other details are similar right down to characteristics curves.Yes you can substitute and it would be interesting to hear the difference in performance if you have the money for 6 pairs. 😀
2SC5359
Becareful about the mica insulators type when you remove transistors,the mica can break or a slice of it will come off.Silicone impregnated type is easier to use although they don't need silicone grease it's good to apply but make sure it's neat no extra grease around the leads.