50uf filter caps instead of 40uf

[Bruce / Mission Amps]

...
If you don't want the rectifier to wear at all, you best not take it out of the box. :-)

So true, but remember "it" all ends up in some kind of a box
somewhere along the path of life... even us.
Like most of us, I choose to take it out for ride.

[Robert M. Martinelli]

If you don't want the rectifier to wear at all, you best not take it out of the box. :-)

Hi MWJB,
To better explain my "attitude", I opened my last post by saying :

"please note that, maybe, my opinion is biased by my "worst-case" design mentality, which is part of my everyday job, if so, I beg your pardon".

In a previous post, I also said that, due to the large tolerances associated with old electrolytic caps, the old caps were probably close to 50 uF already, implying that upping them from 40 to 50 uF wouldn't have been a problem.
( all the more so on a SS design ).

Many amplifiers sported poorly designed PS sections, undersized PTs and OTs, "improperly" biased output tubes ( AC30 ), still they worked flawlessly for decades, so, yes, I think maybe I'm overly cautious.

This said, and agreeing with you that datasheets value are conservative ones, still I can't think about advising to go as far as 250% over a published value to be a safe practice - it might work, but, OTOH, it might not, it depends on the application ( and the tubes' quality; current production tubes are not on par with the old ones IMHO ); some designs include a series resistor between the rectifier and the main filter cap, aimed at limiting the main cap's initial current demand at the cost of a small voltage drop, and, obviously, this helps the rectifier to better "tolerate" larger filter caps' values.

Respectfully

Bob