NZGuitars.com

So I got one of these a while ago, sounds like absolute arse, with both controls maxed out it sounds ok, anything else its just garbage... so I was thinking of gutting it and putting in a new circuit.

Heres the schematic I found of the circuit, I dunno if its worth trying to mod it, has some weird 8.3v power supply... should be able to save the switch and pots and jacks etc, also hoping I can re-use the trannies, I love a used tranny as you can imagine.

I know Reg has mentioned a number of mods before, shall do some forum searching, any other thoughts?

It's just your basic fuzz face circuit with some heavy handed power filtering and voltage dropping in the power section.

Since it's surface mount it makes mods a lot less fun but it can be done.

What were you hoping to achieve with mods? I wouldn't bother trying to cannibalize any of the parts on the board. Those Q's are 30c each at Jaycar or 2c online. Doesn't seem worth the 10 minutes pissing around for 60c.

NippleWrestler wrote: ↑Wed Nov 09, 2022 6:06 pm It's just your basic fuzz face circuit with some heavy handed power filtering and voltage dropping in the power section.

Since it's surface mount it makes mods a lot less fun but it can be done.

What were you hoping to achieve with mods?

I just want it to not sound like arse I should give it another play but my first impressions were its beyond terrible.

Ah, just noticed something: the regular fuzz face uses a 500k pot, although some guys like it with a 100k. I've found it incredibly thin that way though. You can make a larger value pot smaller, but you can't go the other way so you're stuck with the 100k.

The way to run a ff is volume on full, fuzz where you want, and use the guitars volume to clean it up. But the more fuzz you dial in the more low end you'll get because of the cap coming off the wiper.

If you have a multimeter you can check the bias at the collector of q2 which should ideally be 4.5v. I'm not sure how much attention Caline pay to getting that right but they sound the least shit when around there.

It'd likely be quicker to just rebuild a new fuzz face, but maybe that was the plan you had all along.

Interesting! If I can butcher this one I'd be interested to try, looks like a common mod is a 1K reverse log pot for fuzz which makes it more useable, this thing doesn't sound that great unless the fuzz pot is in the top of its range

This is an interesting thread! https://www.reddit.com/r/diypedals/comm ... ter_issue/

So shopping list so far, switch out the 100k pot for a 500k, and create a 1k reverse log pot out of bits I can get at jaycar so I don't have to order bits in

Maybe I should change out that 220ohm resistor in the power supply for a 250k pot so I can tweak voltage too?

jeremyb wrote: ↑Wed Nov 09, 2022 6:35 pm So shopping list so far, switch out the 100k pot for a 500k, and create a 1k reverse log pot out of bits I can get at jaycar so I don't have to order bits in

Maybe I should change out that 220ohm resistor in the power supply for a 250k pot so I can tweak voltage too?

Bro, I got a stack of 1kc pots n stuff

Just hit me up with your shopping list

Looks like mine already has a 500k pot for the level control…

I actually prefer the 100k volume pot personally, it lets more highs through so the circuit doesn’t sound as muddy, I often add a switch to select between the standard 2.2uf input cap and a smaller 500nf-1uf cap to get even more definition and high end through. Eric Johnson uses a 100k in his signature fuzz face.
If you can take out the 8.2 resistor and replace it with a 10-25k pot as a bias knob that might help with 1. Biasing it correctly and 2. Heaps of other tones across the sweep.
You could try replace the BC549s with BC108s as well but may not make much of a difference.

I like 2k and 250k in FF builds, i'd add a boost on the back end (internally switchable perhaps) and as above some level of tweekability (or auditioning) to find your happy place with input and putput caps (C1 &C3) Transistors saveable, but not worth it with their little legs.

Thanks guys, I think I might grab 100k and 1k log pots at jaycar tomorrow and wire them in... if it works out I'll give you a shout Toany for a 1k reverse log jobbie so things work in the right direction

*edit* looking at the graph of a normal log pot vs reverse the sweep is entirely different... PM'd you Toany!!

jeremyb wrote: ↑Wed Nov 09, 2022 7:11 pm Thanks guys, I think I might grab 100k and 1k log pots at jaycar tomorrow and wire them in... if it works out I'll give you a shout Toany for a 1k reverse log jobbie so things work in the right direction

*edit* looking at the graph of a normal log pot vs reverse the sweep is entirely different... PM'd you Toany!!

Just clip some resistors across the outer lugs of the pot(s) to get different pot values. No point going to all the work if you're not into the results. Find a parallel resistor calculator and see what you need... or, wire another pot in parallel with the existing (hook one croc clip to lug 1, another to lugs 2 and 3, then clip the other ends to lugs 1 and 3 of the stock) and dial in the sound you like, then measure the resistance of the second pot, then wire in that value resistor in parallel. Suffice to say, it's more work more expense to change pots wholesale, and you might not like the results you get. At least this way you can roadtest various values before committing.

The 1kC pot is perfect for achieving an even sweep in terms of the increase of fuzz across the entire range of the pot, but if you basically dial both the fuzz and volume control all of the time when using the pedal and use your volume control on your guitar to change the texture of the fuzz than the linear pot is fine. So it depends on the applicant. I use a Fuzz Face that way but still would use a 1kC pot in a build.

As others have said, the bias point for Q2 is important, as close to half the supply voltage is recommended i.e. 4.5-volts, but use your ear. If it sounds good to you, then it sounds good.

As Reg suggested, you can take out the 8.2k resistor and tack a couple of wires on the solder pads and hook up a pot as a variable resistor much like the Sun Dial on the Analog Man Sun Face. You can use this to find the ideal bias point you like, measure the resistance on the pot, and then replace the pot with a fixed resistor value that is closest to what the pot measured. Or leave the pot in. Most use a 10k trimpot instead of the 8.2k resistor so they can dial in a bias they need/want.

If you are going to Jaycar, you might want to pick up some 2N3904s or some 2N2222s to try. The pin-out is different so you'd need to spin them 180 degrees compared to the currently installed transistors. These have a much lower hFe than the BC549. The hFe on the Dunlop Hendrix Fuzz Face, for example, that uses BC108s is in the 260s on the schematic I've seen. The BC549 is typically double that.

Jaycar probably has the worse range of pots in terms of anything useful for guitar pedals. It's mostly the package of the pots that's the problem. No solder lugs; all PCB mounted and really long shafts. Just Linear and Audio tapers too. No Reverse Audio.

The SMD side of things makes things a little difficult in terms of swapping out those components.

So much knowledge on this forum, so grateful to you all!