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Old 6th January 2013, 12:42 AM   #101
6L6 is online now 6L6  United States
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The .22 value comes from a conversation with Wayne Colburn of Pass Labs who said that it was the sweet spot -- just one .22 across the AC worked as good or better than individual caps across each diode.

Regardless, using the .1 across the AC is still going help. Go ahead and use them, I like using what's on hand as well!

If you have a scope, clip it in and take a look. If you don't have a scope, I highly suggest getting one. It's awfully useful for this hobby.
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Old 6th January 2013, 12:56 AM   #102
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.22 -- magic? :-) What about .47, that's what I am using?
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Old 6th January 2013, 01:02 AM   #103
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I actually did pick up a Rigol scope a little while ago. Last used it when I was tweaking my F5 so this will be a good excuse to fire it up. Umm... what exactly would I be looking for?

I'll try the .1, then 1.0, and whatever else I might be able to find in that range. Try to find my own sweet spot.
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Old 6th January 2013, 01:39 AM   #104
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I think you can get too big... Most snubbers you see out in the world are 0.1uf or thereabouts. 1.0uf seems big, glancing through forum discussions on the topic.
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Old 6th January 2013, 02:39 AM   #105
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Interesting read: http://www.hagtech.com/pdf/snubber.pdf

From here: What are the advantages of full wave bridge rectifier with capacitors parallel to diodes? - Electrical Engineering

And here: What does .01 cap on bridge rectifiers do?

I think I have some smaller Kemet caps used as in the last link on my beta24 (of which I still have to trouble shoot one channel). Might have those lying around.

To answer my own question above, I assume I'm just looking for amount of ac that gets through the psu while the amp is warmed up and playing music?
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Old 6th January 2013, 05:08 AM   #106
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I mean ac ripple.
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Old 6th January 2013, 05:43 AM   #107
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no, its not a less than critical part, wrong snubber value on a fast rectifier part could easily mean resonance and resonance on the supply rails can mean oscillation
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Old 6th January 2013, 06:19 AM   #108
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Fair enough! I was just thinking that getting in the ballpark would be beneficial even if not totally optimized. And since I can't measure stuff as in the article I guess I'll just have to try things out. Seems like I can probably start with values a bit less than 0.1uF and move up to from there to see if I can get at least a local optimum.
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Old 6th January 2013, 06:31 AM   #109
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how critical it is will depend on the exact rectifier parts you are using, if you are using SIC zero recovery parts then it becomes quite important and without measurement I wouldnt recommend just trying stuff out. the AX can be a bit touchy already really cant it? I would say anything between 10-100nF would be a good place to start, 1uf is too large IMO
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Old 6th January 2013, 06:49 AM   #110
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On my beta24, I have four caps from the ac to dc terminals as opposed to one across the ac terminals. Any benefit to that configuration?
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