Many information in this thread
https://www.diyaudio.com/community/threads/help-repair-krell-ksa-50s.180314/
I know a few people in France who have worked with this amp.
It suffers from several design flaws and tends to set itself on fire very often upon startup.
In addition the S has a particular bias circuit, but otherwise the rest of the diagram is almost identical to the mk2.
For the finals, you should go for MJ 150XX or 2119X.
Personally, I don't touch these things unless I have a fire extinguisher handy, lack of protection, no soft start, DC coupled, gas plant.
You should find help here but think twice before investing money in this if you don't know exactly what you are doing, it could be very expensive and potentially catastrophic.
Good luck
https://www.diyaudio.com/community/threads/help-repair-krell-ksa-50s.180314/
I know a few people in France who have worked with this amp.
It suffers from several design flaws and tends to set itself on fire very often upon startup.
In addition the S has a particular bias circuit, but otherwise the rest of the diagram is almost identical to the mk2.
For the finals, you should go for MJ 150XX or 2119X.
Personally, I don't touch these things unless I have a fire extinguisher handy, lack of protection, no soft start, DC coupled, gas plant.
You should find help here but think twice before investing money in this if you don't know exactly what you are doing, it could be very expensive and potentially catastrophic.
Good luck
Had this Krell for almost 30 years without a day of trouble. Strange things about electronics, one day they will just decide to self destruct.
Nor have I in the 50 years. I think Dan sometimes designed close to the component limits to get the results he wanted. Sometimes catastrophically so
Where I come from you had to design equipment 200% over spec, well that is so someone else can drop a bomb on it and destroy it before it self destructed.