Forssell JFET transformerless preamp

[dsdesign]

Hi ,
This is my first attempt to build jfet transformerless preamp, one that I find on forssell site.
I build opamp with some matched 2SK170 , and beside that they sound really fine , my trouble start whit gain pot.
I am novice , and cannot figure out where actually +gain and -gain are on opamp .I try few places based on some other designs I found (blue and red doth) but without any success.So if anybody can help ?

 

[Dylan W]

I looked into this recently. That op amp is not the same as the JMP-1. I believe the JMP-1 is a Cohen-style preamp module using 3 of those opamps. Fred posts here sometimes, I think he has some old posts about the JMP-1.

 

[dsdesign]

I looked into this recently. That op amp is not the same as the JMP-1. I believe the JMP-1 is a Cohen-style preamp module using 3 of those opamps. Fred posts here sometimes, I think he has some old posts about the JMP-1.

Tnx ....mistery solved.....wrong opamp.