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Re: What's wrong with the C-47U?

Posted by Perseo (A) on March 11, 2007 at 07:33:54

In Reply to: What's wrong with the C-47U? posted by nc on March 10, 2007 at 18:29:27:

It seems there is a refinement to the theory of Low L, Low C, Low DCR. Some parts that possess these qualities reportedly do not work.

Look at this post: http://www.audioasylum.com/forums/tubediy/messages/118417.html

Unless I am just being gullible, I think it is saying 10 ohms DCR is better than 2 ohms, because the 10 ohm choke has more henries or, if not, a 2 ohm choke with .5 henries has too much wire and iron in it, or so I gather.

Now, I was poking around in some of the old low DCR posts from Jeff and found a statement that Dennis's proprietary amp design, which presumably is ultra-fi, uses some chokes that are only 1 or 2 ohms DCR. Mileage varies, I guess.

Yesterday, I was all set to build a low DCR power supply (L1/C1/L2/C2 per the current recipe) out of good parts I have on hand. A pretty high current transformer (260-0-260, unknown milliamps but it is big, 45 ohms DCR but DCR is of secondary (pun) importance), a 5U4GB rectum-fryer, 40uf poly in oil caps, and a pair of .3H 3 ohm 1 amp Stancor 2690 chokes. Now I am afraid that my chokes are too low DCR or too big, so I would need to buy something different. Oh well, before a few days ago I thought the power transformer was not even mid-fi, so easy come easy go.

Stancor 2690 chokes: http://www.alliedelec.com/Search/ProductDetail.asp?SKU=928-0075&R=928-0075&sid=45F346803041E17F

(I only paid $10 for the chokes, used. Bought them for a DC filament supply, but I now like AC on my filaments).

So, are these Stancor chokes in the category of the C47-Us, as no good for the Low L, Low C, Low DCR power supply?

BTW, when I model the power supply I end up showing 800mV of ripple. Is this a failing of PSUD II, with real world results coming out much lower in the ripple department?

This post is made possible by the generous support of people like you and our sponsors:

Herbie's Audio Lab

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