Quote:
Originally Posted by maxhifi
Does the full wave rectifier raise the B+ enough to require changing the operating points of the tubes? (Specifically the audio output?) is there a meaningful reduction in hum?
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The plate voltage is pretty much the same, with lower ripple. Yes, 120Hz would be somewhat louder than 60Hz with the usual AA6 speaker (this radio has a bigger than usual speaker and a wooden cabinet), but ripple contains higher frequency components which is what you mostly hear with ripple. The ripple amplitude is roughly half with the bridge rectifier, and I used bigger filter caps than the originals (which also helps). But is it meaningful? A manufacturer probably would not have spent the extra pennies for the extra diodes...
I changed out the ceramic coupling caps in the audio path with films.
