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172.11.32.65
In Reply to: RE: ripple #s for 2a3 push pull posted by rage on November 06, 2024 at 07:44:30
Put a 0.47uf cap before the first choke. It will help the hammering of a choke load supply
350v CT Transformer / 1n4007 Full Wave
0.47uf => 5H => 100uf =>5H = 100uf 100mA Draw
will get you 300VDC at 5mA ripple
Your 800uf is hurting your circuit
Follow Ups:
I'm setup with 421V center tapped secondary, likely 5u4gb rectifier and expect 340VDC...
Why is 800uF hurting circuit? Genuinely curious.
Power supply filters are a "necessary evil" meaning you want just enough filtering to do the job and not way too much filtering at random. There is a time component to a filter, the larger the L or R or C the longer it takes to charge the caps and refill the caps. In extreme cases this can act like a compression filter on the audio signal. This is why you are specifying the 0.3H choke with only 10 oums because its "Faster". However in your circuit it really does next to nothing. Also, in some instances, too large of caps can set up instability and oscillations.
But mainly, you can get a better supply with the right sized components as for the same price as a giant cap you can get a better quality smaller cap with lower ESR, etc.
for me the necessary evil is the most fun part!I use the 400uF Wima caps in my SE 2a3 amp following a big 10H Hammond l-critical choke.
They are polypropylene. I would not describe them as slow. Dimensions are roughly 2" x 3".
In the case of my 2a3 SE amp I have seperate power supply and audio chassis. PS is 10H, 800uF. In the audio chassis I use a 10 ohm .3H, then 100uF which feeds finals..following that is a 2k R-dropper and 30uF for the front end 6n7 tube. It is a very clean supply. ~ 60 ohms DCR - enough to give medwin a heart attack.
Edits: 11/07/24
For PP circuits I like an LC filter. It takes a load off the rectifier tubes. Since I build class A, output Z is a trivial concern. The load jus' don't care. A pile of 'lytics can deliver some small ESR numbers. Put a decent film cap along with it and ESR gets small indeed.
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
weren't those guys doing in the neighborhood of 2000uF of bulk electrolytic?
I did tests years ago and could hear that with electrolytic caps as I got > 300uF.
I do not find that result with film caps.
I'm not claiming superiority here - but I do think evaluating some newer DC link caps might pleasantly surprise you.
Not over doing, but you could be doing better. It's a very "Cary" solution. (Massive caps)
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