In Reply to: RE:What about the Pilot SA 232? posted by DAK on August 13, 2017 at 23:38:50:
Examine the SA-232 schematic, carefully. The voltage amplifiers are 'U7 sections. :>( The 12AU7 is non-linear. The phase splitters are 12AX7s setup in the paraphase configuration. If you want to use UL mode "finals", the 'X7 will be "in over its head". Also, paraphase topology is out of favor, due to certain linearity issues. Give Pilot full marks for squeezing acceptable performance out of mediocre circuitry. My hunch is that the O/P "iron" used had LOTS to do with that.
If your power trafo has the requisite extra heater current, switching from 12AU7 to 6FQ7/6CG7 solves the voltage amplifier linearity issue, without parts value changes. To get good linearity, along with a 300 mA. heater, change from 'U7 to the Loctal 7AF7.
Eli D.
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Follow Ups
- RE:What about the Pilot SA 232? - Eli Duttman 07:35:31 08/14/17 (0)