I have just acquired at pair of the Dynaco Mark III Mono Blocks.
I see that one has the correct 5AR4 Rectifier tube.....but the other one has a 5U4GB tube in it.
Both have 6550's for Outputs.
I realize that the 5AR4 is the correct rectifier, and I wonder if the 5U4 was tossed in so the one amp would function.
Both amps also have the SDS Capacitor Boards installed.
I want to run a Quad of KT-88's in them....and I will replace the 5U4 Tube with a 5AR4 Tube and then just Re bias Both amps
Just wondered if my thoughts are right as to why there is a 5U4 Rectifier in the 1 amp?