In Reply to: What the buck? posted by 1973shovel on May 18, 2012 at 19:21:18:
Hi Shovel,I read through this thread, and want to suggest ONE other possibility that I like for several reasons. It eliminates two of the "less than stellar" design choices being discussed in this thread: (1) NO buck or boost winding to degrade the PT's inherent regulation and (2) NO ultra whimpy 5R4 rectifier.
Add a Traid C-56U (as an INPUT filter, fed DIRECTLY by the rectifier tube) onto the back of the chassis, vertically mounted, and PSUD what follows after that, to get it right.
I would also use a directly heated rectifier tube, but NOT the "ultra drop under load" ultra-whimpiest 5R4. How about a 5U4 ??? Maybe a 5V3A.
The C-56U is 2 A. rated, and .79 Ohm in DCR. It should reduce B+ by at least 10% compared to a cap input filter, and maybe as much as 15% less than a cap input, just about right for a more conservative VDC level, with NO whimpy / kluged design parts added.
L2 in my simulation is just a small sized EDCOR 1 Hy 21 Ohm DCR open frame choke, didn't try the Dynaco stock unit, because it is well over 20 Ohms, 60 Ohms DCR as as I recall.
Then you have very nice sounding L1/C1/L2/C2 B+ filters to the Finals, a near ideal and doable design. 482 VDC B+ with 5V3A. Parts cost is quite reasonable.
Cheers,
Jeff Medwin
Edits: 05/22/12 05/22/12
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Follow Ups
- Here is a different approach to try..... - drlowmu 07:25:15 05/22/12 (5)
- RE: Here is a different approach to try..... - Eli Duttman 19:06:40 05/23/12 (1)
- RE: Here is a different approach to try..... - drlowmu 08:34:04 05/24/12 (0)
- Thanks for the suggestions, Jeff - 1973shovel 06:30:01 05/23/12 (2)
- RE: Thanks for the suggestions, Jeff - drlowmu 08:47:37 05/24/12 (1)
- Market - And How, Brother! n.t. - elektron 12:00:02 05/24/12 (0)