In Reply to: Lundahl LL1620cfb posted by sony6060 on December 16, 2014 at 17:29:07:
Hey sony6060
I haven't tried the Lundahl CF offering but there is an article on the K&K audio web site by Claus Byrith describing this approach using the secondary of a conventional LL1664 OPT.
http://www.kandkaudio.com/schematics.html
I also have the .pdf of the article.
I have implemented this for a IT coupled PP EL84 amp I built that runs Pentode mode. I have found this type of cathode feedback works well. You're putting some DC across your output but for the bias of small pentodes it's minimal and after several years of use, I've seen no adverse affects.
You might consider trying this before you throw the cash out for the special primaries. I'm a fan of the results.
Stuben
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Follow Ups
- RE: Lundahl LL1620cfb - Stuben 12/17/1410:11:22 12/17/14 (9)
- RE: Lundahl LL1620cfb - sony6060 12:12:42 12/17/14 (8)
- RE: Lundahl LL1620cfb - Stuben 14:48:55 12/17/14 (7)
- RE: Lundahl LL1620cfb - Stuben 15:12:20 12/17/14 (6)
- RE: Lundahl LL1620cfb - sony6060 15:34:00 12/17/14 (5)
- RE: Lundahl LL1620cfb - Stuben 06:50:42 12/18/14 (0)
- RE: Lundahl LL1620cfb - Stuben 05:08:42 12/18/14 (3)
- RE: Lundahl LL1620cfb - amnesiac 06:50:12 12/18/14 (2)
- RE: Lundahl LL1620cfb - Stuben 11:23:13 12/18/14 (0)
- RE: Lundahl LL1620cfb - Stuben 10:59:58 12/18/14 (0)