Convert Triangulum to Fortin Grind

[sshort86]

Hello all

I've built the Triangulum boost, and I like it ok, but it has a bit too much of a treble spike. My understanding is that the Fortin Grind is essentially the same as the 33, but with slightly less treble. Looking at the schematic for the Isosceles Boost, if I'm understanding correctly, switching to "crush" mode (grind) just adds in an additional 9.1k resistor in the treble boost section. If I wanted to convert the Triangulum to a grind (rather than build the Isosceles), could I just increase the value of r12 by ~9.1k? I read on another post that the Triangulum can be modified to allow more low end by decreasing r16 and increasing r12 so that the total remains 20k. Is there a reason that total needs to stay at 20k? It seems the total of those 2 in the grind mode of the Isosceles is closer to 30k. I am not a schematic wizard, so forgive me if I am way off base lol.

 

[phi1]

Yeah according the the isosceles doc the difference is just that one resistor. I made a version of this with a pot to pan between the settings, but a switch would honestly work just as well, I don’t think you really need the in between sounds since it’s not that bug me of a difference. But it did for sure tame the treble a bit in grind mode.

Triangulum (Fortin 33/Grind)

This is a gift build for a friend who helped me with a video project. He’s into playing metal and has mentioned interest in both the 33 and Grind pedals before. I don’t always post my builds but this one had a few finishing touches that I found interesting so I thought I’d share. Sorry, I forgot...

forum.pedalpcb.com

For the bass resistors, I would stay around 20k total (R16 and R2). I believe changing the total here will mess up the filter. (The TC side of the isosceles uses a 50k pot, but the
R going back to the op amp is different (8k2 vs 3k9).

A 20k trimmer there instead of the 2 resistors would work as an internal bass control.