Argentum 1212 200k trimpot for Q2

[Kroars]

Built a couple of these and while Q1 and Q3 biased to 9v with room to spare, Q2 on the other hand would only go to 10.35v and 10.65v. MMBFJ201’s from Mouser all same batch. Wondered if anyone else experienced this and if the solution would be a different jfet for Q2 or perhaps a 150k-200k trimpot for that one?

It seems to sound/behave just like the original (watching YT demos anyway) despite Q2 not hitting 9v. Just wanted to make sure since I haven’t sat down with the original yet.

Edit: fortunately it was simple enough to replace the trimpot for Q2 with a 200k. Biased wonderfully to 9v and sounds great. Figured I’d leave this up in case someone else comes across this. Seemed odd since all the jfets were FSC from Mouser and Q1 & Q3 biased easily enough. Could be a fluke, also could be worth while just using a 200k for Q2’s trimpot (upper left hand corner of pcb).

Killer pedal.

 

[manfesto]

Wanted to add to this!

Built my second Argentum just now, the first one I had to go through a half-dozen J201s to find one for Q3 that hit 9V; for this one, I once again couldn’t bias Q3 originally, and *none* of my J201s got below 11V.

I didn’t have any 200K trimpots, unfortunately (that was plan A), so I changed R12 to a 4K7 and hit 9V easily. Sounds exactly the same as the last one I built, woop.

Anyone building one of these should just buy 200K trimpots out the gate, but if you’ve already built it and don’t have any handy, try upping R3/R9/R12!

 

[maertz13]

way late here, but I had the same issue. got 2 of them to 9v on the dot, last one wouldn't get below 10.something. fired it up anyway, and it sounds great. I'm sure it's a factor in the sound, but it still sounds good, so I left it alone. the way I see it, tolerances on those old amps were probably super loose, so no 2 sounded exactly the same. and my pedal reflects that

 

[Fuzzmax]

Since i put the argentum in the disappointment section
(Other thread), i remember after reading this thread here that i had the same incapacity to bias one of the transistor to 9V. Must be the same one you guys talk about. Can there be enough difference from 10.something Volts to 9V for one of the transistor to change the sound and make it sounds more like the OG pedal and thus, put it in the like section?