Seems I can't leave anything alone.........for long & have a few more questions............
If I were to change C4 to 2µF but still used NFB would that increase stability any? Would C3 stay @ 200 nF? (Velleman used three 680nF's in parallel to get ~2µF in their K8010 KT88 mono amps.)
Could I add 60V zeners across C29 &C31 to stabilize bias? I think my bias supplies measure 62V. There seems to be some drift.
If I were to add the grid stopper resistor to U3 (pin2), would C3 connect to the grid side or R14 side? I'm thinking R14 side but want to make sure.
If I were to change C4 to 2µF but still used NFB would that increase stability any? Would C3 stay @ 200 nF? (Velleman used three 680nF's in parallel to get ~2µF in their K8010 KT88 mono amps.)
Could I add 60V zeners across C29 &C31 to stabilize bias? I think my bias supplies measure 62V. There seems to be some drift.
If I were to add the grid stopper resistor to U3 (pin2), would C3 connect to the grid side or R14 side? I'm thinking R14 side but want to make sure.
Now that I've listened to the amp for 50 hrs or so I find it to be very musical, powerful & reliable. Here is the schematic of the finalized mod.. I ended up switching the outputs of the phase splitters so as not having to move the OTP leads. I also made the front panel easily removable to check the bias by gluing small bar magnets to the panel and chassis sides. I also glued up a dust cover to use when the amp is not in use. It has been a fun and educational project which has turned out great. Many thanks to baudouin0 for his invaluable help and patience. 🙂
