My FET fx loop schem

[Morocotopo]

Hey guys, I want to show you this schem that I put together, maybe it will be of some use for someone. It all started here:

http://www.diystompboxes.com/smfforum/index.php?topic=94906.0

My original idea was to make an external fx loop for my tube amp, in a pedal format, so as to be able to put it in my pedalboard. The design morphed from an opamp based one to a JFET based one, and here´s the final schem:



The design is optimized to go between the amp´s Fender-like pre last triode (a gain stage, so output taken from the cathode via coupling cap) and the power section´s phase splitter. In order to have the most headroom possible I used the voltage upverter, to get around 31V for the power. It works well, the only quirk is that, when panning, in parallel mode, from the fx path -with the fx off (true bypass)- to the dry path, the volume drops a little.Not with the fx on. Close enough for me! And also, I believe the signal path is inverting. Since all the signal goes through, that´s no problem. In more complex setups it might have some consequence.

Hope someone finds it useful! Any questions welcome. Thanks to all that helped me!