Schmidlapper
Super Member
I have been doing lots of initial research and have come down two options regarding output transformer secondary taps. The 7868 tube data sheet says in Class AB push pull the optimal OT reflected impedance is 6500 ohms, and based on the R-4359A OT secondary taps turns table created by Secret4mula linked.
For a 8 ohm load, I could use the E1 to E4 tap for 5800 ohms with E4 already common, or I could use E1 to E3 and get 6800 ohms and move the ground wire from E4 to E3. Am I correct here that I can just move the grounds from tap E4 to E3 without affecting the feedback since it comes off E1? Is it the better choice here to get as close to the optimal 6500 as I can, if it goes over just a little? I know the obvious downside is slightly lower output wattage. So here I am looking to the community for some input?The usable combinations that I found are listed on the cleaned up schematic.