The 431 is a fairly simple wind. Not nearly as complex as another I have used( and had wound, and seen the instructions for ). They're not bad, just not excellent.

If we want to build like Doc Bottlehead does, the Dynaco stuff is a reasonable starting point. Doc's stuff is adequate but usually leaves you wanting more, hence the upgrade steps he offers. It is also allowing him to put a product out at near the bottom of the price pile. Not criticizing Doc, just explaining as I see it. I hope it does not offend anybody.
regards,
Douglas

If you think of an amp as a modulated power supply, it makes perfect sense to make the PS as tough and capable as is possible. This sometimes gets into Forklift territory, along with consult your floor loading specification...

I'll say about the OPTx project that it is going well. I am designing a new wind and hope to get Phil at Heyboer making me the first prototype. It's a Tertiary winding design, similar in operation to the big Dynaco A441, but done a bit differently. Something more like a Quad II OPTx in turns ratio. It is about a project and a half out. I can't make up my mind what valve to use with it. Probably 813...that one has got too much potential. Run it gently and take ~60W or so in Class A. Definaltely a winter amp.

'block, just to refresh mymemory, you got the 8039 choke for Guinevere didn't you?
regards,
Douglas