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RE: Brook 12A bass response? 1953 update

Posted by Thermionic27609 on March 13, 2017 at 07:10:51:
Iain42,
Where is this updated Brook schematic available? I've found the 1950 SAMS schematic and thought that that was the only one -- with a few errors.
Are you saying that they increased the RC input to the 2A3s to 1uF/68k? Or 0.5uF/68k?
Edit: I found the Brook 22A schematic, which appears to be virtually the same circuit as the 12A implemented with 12AU7s and 6C4s instead of 6SN7s and 6J5s. It doesn't have the same high-pass points as the 12A. The input to the PI is DC coupled from the preceding 12AU7 plate, and the input capacitor has been increased 5x. The driver is coupled to the 2A3s with 0.5uF/100k, plus 1k grid stoppers.