I may be wrong, but here is my thinking.
The specified peak reverse voltage of a high quality vintage 5AR4 is 1500v,
https://drtube.com/datasheets/5ar4-amperex1958.pdf
but I've heard it said that the new copies by Chinese and Sovetek might have much lover PIV limits before they self destruct.
It seems that in normal operation the tube will have PIV equal to the difference between the B+ DC in the filter caps and the negative peaks in the transformer secondary. So this is about 800v right? I guess the thinking is that some of the newer tubes even 800v might be unhealthy.
The addition of the diodes removes the negative from the plates so the tubes don't see a high peak inverse voltage.
Yes, the diodes alone would work just fine. The tube is mostly there to slow the rise time of the B+.
The specified peak reverse voltage of a high quality vintage 5AR4 is 1500v,
https://drtube.com/datasheets/5ar4-amperex1958.pdf
but I've heard it said that the new copies by Chinese and Sovetek might have much lover PIV limits before they self destruct.
It seems that in normal operation the tube will have PIV equal to the difference between the B+ DC in the filter caps and the negative peaks in the transformer secondary. So this is about 800v right? I guess the thinking is that some of the newer tubes even 800v might be unhealthy.
The addition of the diodes removes the negative from the plates so the tubes don't see a high peak inverse voltage.
Yes, the diodes alone would work just fine. The tube is mostly there to slow the rise time of the B+.
