The Partridge OPTs on the amp I recently acquired are marked 8000 Ω as shown below. I am assuming that this means that the anode of each PP valve is seeing 4000 Ω, which translates to turns ratios of 32 for the 3.75 Ω speaker tap and 16 for the 15 Ω. Please confirm that I'm not talking :cr@p:
(If you don't trawl the DIY section, see my idea for the design: https://www.avforums.co.za/index.php/topic,69276.0.html )
(If you don't trawl the DIY section, see my idea for the design: https://www.avforums.co.za/index.php/topic,69276.0.html )