Newbie here with a first version (I think) RD50 from December 1980. It has the 27 ohm cathode resistors. No schematic found to match what I have. My problem is that I did the BobW liliter channel mods and love the drive when it's full on but when backing down the gain, it sounds somewhat like blocking distortion in the limiter channel. I'm wondering if I may have some circuit differences from the later versions that he modded. Any suggestions on what to look for? Thanks in advance for any help.
I followed this list of changes to the T:
1. disconnected the cathode grounds and ground leads from C10,R12 at V1-8.
2. Added a 5uf and a 1.8k at V1-8 and connected the grounds to the C10,R12,ground node.
3. replaced plate resistors R9 (470k) with a 180k, and R11 (4.7M) with a 150k.
4. replaced R10 with a wire jumper.
5. removed grin wire at V1-7 and added a 150k series grid resistor.
Initially also added a 470pF across the Clean Vol pot, and a 1000pF across the Limiter Vol Pot.