Has anyone else built one of these? I just finished testing a board I made, and it has an insane amount of gain in it with J201's in it. I think I'm going to replace them with 2n5457's or something, it gets pretty nuts.
(http://i163.photobucket.com/albums/t282/Gutstwohand/engchbot_zps15736964.jpg) (http://s163.photobucket.com/user/Gutstwohand/media/engchbot_zps15736964.jpg.html)
(http://i163.photobucket.com/albums/t282/Gutstwohand/engchtop_zpsc7d93a5b.jpg) (http://s163.photobucket.com/user/Gutstwohand/media/engchtop_zpsc7d93a5b.jpg.html)
(The board had issues -- the links you see are the tip of the iceberg...
I've breadboarded it. You are right, it's a crazy amount of gain. I've built the Supreaux Deux and I built one of these amp sims based of their ideas that's based on an old Ampeg Gemini amp I owned years ago. The Ampeg sim has just insane amounts of gain. The Supreaux is more tame. I've done the Eighteen on breadboard and built the Uno. Both of them have nuts levels of gain too.
When I had them on the breadboard, I tested all sorts of combinations of JFET's. The two that I remember being the best at bringing down the gain are the 2N5457 and the MPF102. But, sometimes they change the character too much. The Ampeg sim has so much drive that to get the character of the original I can't turn it above about 2. After that it goes into some kind of modern metal uber-gain thing. But, I stuck with the J201's in it because when it is turned down, it sounds better than with the lower gain JFET's.
It's worth messing about with the various different JFET's though. Definitely illuminating.