In Reply to: RH84 test amp: driver stage wiring change = lower THD% posted by deathtube 667 on September 15, 2016 at 16:46:39:
Hi DT, i have always connected the driver tube plates to seperate B+ dropping resistors. I felt that the circuit was more "balanced" that way and each section could operate more independantly since each half of the at7 drives its own power tube. It is reassuring to know that this arrangement results in lower distortion in the circuit. Thank you for exploring this. Kinda off topic but have you tried the rh circuit with octal driver tubes?
I have always preferred the 6sn7 and 6sl7 and other octal tubes over the 9 pins mini tubes. The 6sn7 seems to be one of the best sounding tubes around. The octal tubes have a sturdier base and aesthetically better appearing than the mini tubes. I have wondered if one were to optimize the RH type circuit for the 6sn7 or 6sl7 what circuit changes would be necessary? Have you tried any of those tubes?
Edits: 09/17/16
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Follow Ups
- RE: Have you tried the RH circuit with octal driver tubes? - DAK 13:27:59 09/17/16 (1)
- RE: word of caution ... - deathtube 667 14:13:51 09/17/16 (0)