More capacitance for tube rectified filter caps?

[honkyjonk]

Hey folks,

This is in regard to the 'ol RodC modification of an Akai M8 amp. I'm replacing the multicap filter cap (2X20uF 350V) What I have in the drawer is a couple 33uF 450V caps. These should be fine right?

[Darlington Pair]

Hey folks,

This is in regard to the 'ol RodC modification of an Akai M8 amp. I'm replacing the multicap filter cap (2X20uF 350V) What I have in the drawer is a couple 33uF 450V caps. These should be fine right?

That's totally fine.

[ashcat_lt]

First of all, a smallish 33uF could be the same value as a big 20uF and they could both still be in tolerance.

Second, bigger capacitance means lower cutoff which means better ripple rejection.

[floid]

tube rectifier datasheets typically list a max filter cap value, determined by the cap's current draw - pull too much and you fry the tube. a maximum value's tolerance range may put a particular example beyond what the tube can handle.

[Matt C.]

tube rectifier datasheets typically list a max filter cap value, determined by the cap's current draw - pull too much and you fry the tube. a maximum value's tolerance range may put a particular example beyond what the tube can handle.

this is what I thought too, but now that I'm looking at a bunch of tube rectifier datasheets, they're all listing capacitor sizes for "typical operation", not maximums. so, I guess I'm not sure what the scoop is. I'd imagine a huge capacitor could cause problems but I bet increasing from 20uf to 33uf would be a big deal.

[Jim Williams]

If a tube rectifier can't handle in rush current, pull it out and solder a couple of IN4007 diodes in it's place.

I would use 470 uf at 400 volts, if they would fit.

[themagicmanmdt]

hush, jim, you'll ruin the magic

If a tube rectifier can't handle in rush current, pull it out and solder a couple of IN4007 diodes in it's place.

I would use 470 uf at 400 volts, if they would fit.

[Orpheus]

I'm going to concur with Mr Williams. I freaking hate tube rectifiers