Been reading about the 0.22uf snubber capacitor.
Just want to check, the recommended location for it is before the diode bridge across the secondary
Debra
Just want to check, the recommended location for it is before the diode bridge across the secondary
Debra
Snubber network is different for each type of transformers, there is no universal value. Mark Johnson showed how to select the right one with his jigs and oscilloscope. Very simple to build in dead bug form with copper surface as gnd.In fact, it is CRC snubber.
True! And with the proper tools it's easy. Without the proper tools, the 0.22uF is better than nothing.
If you are using a torroid, the leakage inductance is probably in the tens of microHenries. If you're using an EI transformer the leakage inductance will be in the milliHenries.
Christophe Basso is your go-to-guy and you would probably find this paper he wrote for APEC illuminating: http://cbasso.pagesperso-orange.fr/Downloads/PPTs/Chris Basso APEC seminar 2011.pdf
Just looked at my Pearl 2 power supply -- no snubber and no ringing -- using an Amveco trafo and bridge rectifier.
On the other hand, real world issues on an EI core trafo -- this traf was salvaged from an HP 465 amplifier:
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Moved here from elsewhere ...
15va transformers (one per rail) to MBR20200 rectifiers feeding 10,000uf 63v T-Net (4 pole) caps raw to super teddy regs...I had all/most the bits knocking about and just sorting out the layout with the existing case I have.
Luckily it looks like it all fits OK..
IF you have an extra case I'd strongly suggest placing the raw PSU in it by itself. Both my Pearl and Pearl 2 were only really quiet when the transformers were 3 feet from the board.
That said, I'm really looking forward to seeing how the Teddyregs work out in your build! They are neat bits of kit and I've always wanted to try them.
That said, I'm really looking forward to seeing how the Teddyregs work out in your build! They are neat bits of kit and I've always wanted to try them.
You would be better off with LM317/LM337 with the adjust pin bypassed, even better with the Sjostrom or Jung. The Super Teddy Regs are very quiet, but very slow and they will put back on the power supply rails harmonics of the fundamental. They were among the worst regulators tested for the Linear Audio article. Here are some comparisons of the THD on supply rails. In order, Super Teddy, LM317, Sjostrom, Jung:
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I know it seems a bit off topic, but roughly what was the build cost for this? Minus enclosure and plus the pass labs fet/board kit.
Thanks a lot, I've been eyeing this for a long time and it's looking like I may actually do it!
Thanks a lot, I've been eyeing this for a long time and it's looking like I may actually do it!
So always willing to take advise...revised cases. One for the PSU one for the Pearl's..WTF they just fit..
Regs..Mmm, I use S-teddy regs in my existing phono amp with superb results over Jung/Weeks super regs or Russ white shunts but will now (first) load the board with 317 337 variants and give them a go. I can always just pop the teddies in to see at a later stage.
I've checked and I don't have any 2K2 resistors but I found 2K49. Will it be OK to replace R6? Or I can set P1 at 700R. That will make 2K2 in series with 1K5 R6.
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$200 for PassDiy boards with jfets, and $300 for additional parts is what I spent on mine.
I don't have as much experience as you, but at home every toroïd humm (and, as long as I remamber, I've always heard the toroïd in all my gears). I'm used to it (even if the noise of the one in my Aleph J is sometimes annoying).
I used Rcore for the first time in a dual mono psu for a Phonoclone. There was no noise coming from the box with the two 50VA Rcores.
Then, I read an interview of John Curl (link) where he says that, for small signal application, toroïd is not the best choice (see P9) so I choose a Rcore for my Pearl2.
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I understand your belief and one cant diss the tech but I use my ears over 'tech' to determine what 'sounds right/best' IMO the S-teddy reg is sonically superior in my system to others and I've had them / tried all over the years. Just to clarify I have the 4 transformer, 4 cap, 4 reg set up in my current phono front end which is the LT1115 - LT1010 buffer, as used in the Dynavector, mine is a DIY jobbie though.
I'll do a basic schematic to outline my thoughts....which I'll post when my internet will let me...