Best use of S-265 opt?

[Don Ericksen]

Recently I was given a pair of S-265-Q replica transformers that a friend had ordered and decided against using. These are the old Peerles transformers that were used in US versions of the Williamson amplifier. It can be used as a 10K unit with 50% screen taps or a 2K5 unit. They weigh over ten pounds apiece and are good supposedly for about 30 watts apiece.

The Williamson is said to not be unconditionally stable and uses cathode bias. I want an amp that I can use with Quad electrostats as well as other speakers (Williamsons supposedly are a poor choice with these). Can I just use, say, the various ST70 upgrade boards to drive these instead of the Williamson circuit? Or is there some thing about the Williamson fromnt end and driver that makes it work with this high plate load for the output tubes?

If I use it as a 2500 0hm transformer by paralleling the primaries, is this workable with some triode tube for reasonable power?

Finally, is there a reason these can't be used in a unity coupled type circuit with one in the cathode and one in the plate circuit, like the Mcintosh?

[Bandersnatch]

hey-Hey!!!,
I also have some modern build S265's. I had them assembled with extra U-L taps in 10% increments from 20% to 40% and deleted the 50% tap and split CT which allowed a parallel connection at 2k5 a-a. I have always used it in the 10k connection. I've built with 807, HY69 and 1269, 1619 and 1624 and finally the 4E27 running nearly 140 mA per leg including the front end stage.

I absolutely love them, and have plans to build more amps with them. It is more of a revelation to discover just how many tubes can be used with the 10k load and still stay Class A. 813's are to be next...

Who wound yours? I got mine from Heyboer for $86 each!
cheers,
Douglas

ps. they're rated for 40W and with M6 it is probably colser to 60W.