Friedman Twin Sister Circuit?

[psychepool]

If this question violates the forum rules, please let me know.

I became interested in build the Friedman Twin Sister.
I was able to find the Dirty Shirley schematic by searching here and other web pages, but I couldn't find the Twin Sister schematic.

https://ampgarage.com/forum/viewtopic.p ... ty+shirley

Twin Sister is guessed to be a configuration of two Dirty Shirley preamp that can be switched.

The gain switch probably has the same configuration as the Dirty Shirley, but the difference from the Dirty Shirley is that a bright switch has been added.

My guess was that this was the treble bleed cap on gain pot pins 2 and 3, but after checking with some gutshots, I can find no switching was applied to the gain pot.

Does anyone have any information about Twin Sister's Bright Cap? If it is not applied to the gain pot, I think it is likely to be a cap applied in parallel to the 470K stopper after the second stage. If anyone has accurate information, please share.

[Littlewyan]

I believe it's a cathode bypass cap on the last gain stage. I think Dave said so on one of the other forums.

[psychepool]

I believe it's a cathode bypass cap on the last gain stage. I think Dave said so on one of the other forums.

Thank you for answer.
Is that the bypass cap you mentioned, the red boxed spot in the image below?
If you don't mind, can you tell me where this forum is mentioned?

bypasscap.jpg

[Littlewyan]

No it's on the stage before the cathode follower and I can't honestly remember I'm afraid. Would have likely been gearpage.
What you're looking at is a capacitor used to shave off some high end.

[Tone Lover]

Try a 22u on that 820k resister and see what you think. If to much bass go lower