question on fuzz face turret layout

[analog_bham]

Hi all! I just saw a photo of the Jam Fuzz Phrase LTD on turrets and wondered if someone would be willing to "check my work" on it before I get to plugging away. For some reason, the FF circuit gives me more trouble than anything else, but I can't seem to stop trying...

I have screengrabbed a photo of the Jam layout and was hoping someone might be willing to just peek at my connection labeling to make sure I haven't goofed it up.

Thanks!!

John

 

[andare]

My suggestion is to breadboard the circuit. It's the only way you will ever learn how these things work. Then you can make your own turret board layout, like I did.

What trouble is the FF giving you?

 

[analog_bham]

I’ve been breadboarding but am having issues with sputtering/gating despite biasing to 4.5v. Not sure what the issue is.

 

[andare]

Do you have the right transistors?
Get two units with leakage below 100uA, gain can be anywhere between 150-300 depending on the specific silicon transistors, both can have the same amount of gain (the JHF1 is around 260 iirc) or stick to the classic germanium gains, 80 for Q1 and 120 for Q2.

Of course double check the breadboard, it's easy to make a mistake.

 

[analog_bham]

Yeah. I have fiddled around again and got it going. But the fuzz pot either grounds out the signal or when moving wires around, doesn’t seem to do anything. Trying to figure that out right now…

 

[analog_bham]

Feels very much like one of those, “keep plugging away at it and there are lots of lessons to take away” kind of situations.

 

[andare]

There are some great breadboarding tutorials on this forum. Take a look at those for a good workflow

 

[owlexifry]

+1 breadboard the circuit.

tbh breadboarding is actually easier than building a pedal of the same circuit. there’s no solder involved, so it’s really really really easy to fix an error.

start with an LPB-1 and then go from there.

 

[analog_bham]

i have been watching a ton of breadboarding videos lately (and spending a LOT of time with JHS' Short Circuit series) and joined the Coppersound Mod Club as well which is basically a breadboarding monthly subscription with walkthrough videos and stuff. It should start March I think.

i've been doing pretty well with breadboarding stuff before the fuzz face. i figured out tonight that i was basically messing up with the way that i was grounding the cap on the fuzz pot. i was taking the ground from the 20uf cap and going to ground along with the ground from lug 1. i went from 20uf cap to lug of volume and then to ground from there and it works. i don't have an explanation for why that changes anything but i saw someone else's ff that connected those lugs and then to ground. would love to know why that is if someone could enlighten me.

i also ended up changing the values of the pots to actually have some meaningful change along the sweep. seems to be working pretty well now.

 

[andare]

Both the 20uF cap and lug 1 of the Fuzz pot have to go to ground, doesn't matter how. On a breadboard, I would connect them to the ground rail individually, each with its own jumper, for clarity. It's another benefit of breadboards, I can spread out the circuit and see where everything is going,

As for changing component values, I always use a C pot for Fuzz because it allows fine tuning at the high gain settings - it's easier to find the sweet spot where there's enough gain but it cleans up completely. This should be standard in every FF, IMHO.
Sometimes I use a 100k pot for Volume to get rid of some of the boominess - the smaller the volume pot, the less bass.
And of course I use a smaller input cap if the tone is too woofy. Analogman uses 1u, 470n is also a good starting point. They both keep the FF character intact but there is considerably less rumble.