SET amplifier Q
On Wednesday, 7 November 2012 13:44:12 UTC+11, Phil Allison wrote:
"patrick-turner" If you'd described the circuit more fully, I may not have made my assumptions. ** FFS, Pat READ the description in my first post. " The tube line up is two 300Bs in parallel and one 6SN7 per channel, 260mV sensitivity, " .... Phil
I'm either forgetful, because I did read your first post, or, like so many reluctant examples of the species Homo Wrectus, I am not perfect, and sometimes need someone to repeat something they typed.
Though this is a little OT, whenever I think about 300Bs and SETs, I can't help think about the pair of rare spare Jadis OPTs I have here. I think they'd each work well with a pair of KT120 in triode and in series with cap feed to the OPT primary. About 22Watts of pure class A triode is possible. Although the Futterman type of driver could be used, or the Technics version which makes each series tube work as cathode followers, I'd prefr an EL34 in triode with a Hammond IST, so the secondary can float on Vout. The driver triode then has an easy task, no need to aim for 2H cancelling, and some mild GNFB would fix their minor mistakes to let tubes perform more better.
Getting 800Vdc is easy with an existing CT winding meant for 5U4 and 400Vdc.. Just use a bridge with 8 x 1N5408, and two elcaps, and take CT to join of caps. But I doubt I'll ever find the time.
Patrick Turner.
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