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In Reply to: RE: Look who has gone LSES on his power supplies, in retirement years posted by Al Noakes on January 27, 2015 at 03:18:46
Al,
I am not sure of anything, but I am having FUN posting. Hey, I never noticed the small "c" Kyle pointed out, but its there. Looks to be "c/L1/C1/L2/C2" for a filter.
Am not sure whose chokes they are, look to be custom wound or ???, not Hammonds.
Certainly Ls are SMALL in mass.
Cheers,
Jeff Medwin
Follow Ups:
I just bought a couple 450V/47u caps to fill out an order, and they're about that same size. Seriously, no legitimate designer is using the weak PS designs you're publishing here.
--------------------------
Buy Chinese. Bury freedom.
The amp uses a 274B rectifier which has a maximum input capacitor of 4uF according to the WE data sheets. That would make it a cap input supply regardless of the relative size of capacitor compared to other amps/rectifiers.
The small sized cap is likely full size for the application.
Considering that you can get a 4uF 630V film cap for $4, it's a wonder that there is a one dollar electrolytic in that spot on a $1200 headphone amp.
The ebay ad says "Dual Pi-Network".
A Pi-Netword does not use a small "c", it uses a big "C" for a cap input filter.
BTW, "big" is a relative term. As you pointed out the 274 will only take a 4uf input cap.
A little "c" in front of a critical inductance input choke is a handy trick to lower the charging current seen by the choke and increase the B+. Most times that cap will be a .1uf to 1uf or so.
The price paid for using that "trick" is, now each of the diodes are off for part of their half cycle when they would have each been on, in turn, for that whole half cycle if the filter were left as a true critical inductance choke input filter.
But the trick does work just fine and I have used it many times myself.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Jeff,some "thinking out loud" here...
What if DF went with the chokes he did as they were the closest thing to what he needed available off the shelf at that time?
the idea being that the power transformers and chokes were selected given what was available.
today we can call heyboer and custom order iron. maybe it is time to revisit L-Critical choke input power supplies. I remember you built a 4 henry on your existing core for a phono pre project... 4henries would be just about enough for choke input duty on a stereo 2a3DC amp. 8 henries would do the job for monoblocks... a different story altogether.
if you get 4 henries in a reasonable DCR (lets say 20 ohms to stick with your logic)... and you spec your PT accordingly... now you've got choke input, low mass chokes and low DCR still..
go two stages and manipulate the caps to get the dampening you like.. the second choke can be triad c40x even.
again DF didn't have the luxury of an 8 henry choke in low resistance... maybe things would be different today if he didn't have a stash of those stancor chokes or if Hammond quit making the PT he used.
TRY IT IN PSUD. I bet you'll find that you can get the same parameters you sim for with LSES.
Edits: 01/27/15
Rage,I will let YOU carry the torch on further L experimenting.
I am getting ready to try to copy DF's most recent amp / parts / implementations, and apply them to a tweaked ALTEC A7-800 system, and get my phono and 10.000 LPs spinnning again.
Over a week ago, I heard Maurizio Pollini play Beethoven's Sonata No.21 in C major, the " Waldstein " and I quickly came to realize that the music is more important to me than either the L or the C or the or the R value and type.
That particular music has been going "over and over" in my mind, it won't leave me alone, it is haunting me, can't stop thinking about it.
Today in the mail, a LP arrived, VOX / Turnabout TV-S 34394, mint - never ever played, of a young Alfred Brendel doing this same piece. It gets heard, with a co-worker friend of mine, tomorrow.
Have fun, I am. Ohh, from what I heard several years ago on my first testing of LSES , there was a BIG bass speed and transient difference between 20 Ohms and 10 Ohms and 8 Ohms of L DCRs, listening on ALTEC 515Bs and 802-Ds. That was when I coined these following terms up here :
20 Ohms or less Ls, " High Fidelity "
10 Ohms or less Ls, " Ultra High Fidelity".
There was also a huge differences heard by me back then, using one, two and three clip leads in parallel, connecting the B+ filter parts together. Hence your new 12 AWG wire from eBay.
The real question in my mind these days has been this..." How did G-d allow L.v Beethoven to write such music, and have an aging Pollini play it back so wonderfully ??
Jeff
Edits: 01/27/15
Why do you have to copy Dennis's amps? Why can't he just build you one for the cost of the parts? Or even the parts you supply. You have certainly earned that with all the free advertising you give him here.
And after all you have both said many times it's the execution that matters the most. You say only Dennis has that special black magic to spin straw into gold. Seems when anybody else buys the parts and puts a DC coupled 2 stage 2a3 amp together and is not overly impressed with the performance you always claim it wasn't built right.
So even if Dennis can't afford to buy the parts for you why can't he at least assemble a near perfect amp using the parts you supply?
Some friend he is!
.
.
I like your ms-paint work there gargoyle.
It's an interesting paradox... the one thing that has griped my ass over the whole following of Jeff's ideas... lead out surgery on transformers and chokes.
I've wrecked countless chokes and even done some damage to a nice power transformer.. Not to say the whole idea is stupid, but moreso I am just too aggressive when trimming leadouts at 1" from the transformer.
Even then, many times I've opened up the chokes and soldered the magnet wire directly to the new leadouts..then glued everything up.. most successfully with gorilla glue.
The problem is then that I have little confidence in the chokes durability when working on the new leadouts..and that bothers my OCD a bit.
Anyhow, the SILVER LINING. I was at work on a 7 tower AM array where we had trouble with a 220 volt 20 amp contactor that switched one of the towers in and out of the pattern. The problem was the leadout had broken off from the terminal strip. The other engineer being my equal or better at being destructive ripped the entire leadout out of one of the coils for this relay. $1500 to replace the whole contactor... or scrounge ebay for a coil for the 1960s EF Johnson contactor.
I burned the enamal off the magnet wire and soldered a new leadout on. Then I put a bunch of gorilla glue on the whole thing. Two years later it still works great. Drives me nuts, but hasn't failed yet! Ugly as hell but it saved the day!
Thanks Jeff!
We will carry on after DF and JM are gone.
- LSES tube amp builders of the World
"The eternal flame"
That is very clever!
The poor guy was not fortunate enough to get the "cornhole torch" as that is reserved for the most elite of LSES builders.
I think his filter chokes were too high in DCR for such an honor.
Better luck next year.
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