Sweet, good to know for the future as you say. On a similar note, what are your thoughts on the TO-202 transistors on the amp boards? Are these part of VAS, or for bias generation? As they are low-CoB parts I've been wondering if that spec is important for the sub or not. TO-126 seems to give the closest matching specs all round, but I'm not sure if heat dissipation is important given the factory package, which is surely better with TO-202 than sealed-back TO-126. Appreciate your thoughts as always. I've edited the posted schematics to reflect the mistakes noted so far, and added the suitable modern subs. I'll post them for everyone as soon as I'm sure they're actually correct. TR204 on regulator board is unidentified, from the schematic I'm guessing it's the complement to TR209 (2SA872A), so 2SC1775A?