K&K Audio / Lundahl Transformers

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K&K Audio / Lundahl Transformers

LL1638, LL1673, or LL1685 - Which One?

206.228.220.39

I'm working on a PSU for a 26 tube preamp. I want to use a cLCLC design followed by a CCS-VR tube combo running at a total DC draw of 52mA. Using PSUD-II, I find I can make an acceptable-looking PSU with any of the above chokes, at 10-20H inductance by varying the cap values (something around .44, 47, 100uF seems to be good in most cases).

Based on the total current draw of 52mA and the application (class A single ended preamp) which choke would you recommend?

Follow Ups:

RE: LL1638, LL1673, or LL1685 - Which One? - KevinC 14:06:33 03/08/12 (3)
Unless the difference in the DC resistance of these chokes figures into the model in some substantive way, the only considerations that occur to me are the size and the correlated maximum ripple voltage. Since the supply is capacitor input, ripple voltage is not an issue, so that leaves size...

Kevin Carter
K&K Audio
www.kandkaudio.com
- RE: LL1638, LL1673, or LL1685 - Which One? - Maxamillion 15:48:56 03/08/12 (2)
  It's really still a choke input supply with the first cap at only 0.44uF, hence the small c. Transformer secondary voltage is 350V, tube rectified using a 5U4GB.
  Are any considerations of the recommended operating current important? 52mA is well below the recommendations for all the chokes listed - should I try to pick a choke with lower recommended current to get as close as possible or doesn't it matter?
  
  Edits: 03/08/12 03/08/12
  - RE: LL1638, LL1673, or LL1685 - Which One? - KevinC 16:50:26 03/08/12 (1)
    Ah, communication! Small c looked like a missed shift key to me...
    
    Well, as I implied, that does change things. All things being equal, the lower current choke (LL1685/17H) will perform closer to it's specs. It would be my choice if it can integrated into the design without low frequency power supply resonances.
    
    Kevin Carter
    K&K Audio
    www.kandkaudio.com
    - RE: LL1638, LL1673, or LL1685 - Which One? - Maxamillion 17:17:15 03/08/12 (0)
      Thanks Kevin,
      
      That's very helpful info!

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