How do I wire a Stupidly Wonderful Tone Control in a Fuzz Factory clone?

[Nicofromfrance]

Hi all,

Here is a Fuzz Factory clone I purchased from Musikding and built recently:


I am pretty happy with it so far, as it is my first build. But as many users also do, I'd like to tame the excess of trebble that it can provide, with the help of a tone control. I came accross the Stupidly Wonderful Tone Control mod http://www.muzique.com/lab/swtc.htm, which seems to work very well with fuzz. I'd like to do the first one:


The problem is that I don't have lot of skills when it comes to read an electronic schematic as I'm still a beginner, I have difficulties to translate the schematic into a "physical" scheme, so as to know how to wire it to my Fuzz clone. So far I manage to make that (my scheme is adapted from another scheme I found there http://forum.dijonstock.com/viewtopic.php?f=1&t=10626):



Could you guys tell me if this is a good way to wire the SWTC mod to my Fuzz? I chose a default value of 100k for the tone pot, is there a better value in your opinion, considering the Volume pot of the Fuzz clone has a 5K value?

Thanks in advance!   

[Govmnt_Lacky]

According to the schematic you provided, this is how you would need to alter the drawing that you posted:

1) REMOVE the connection you have (Pink line) between the Tone pot and the Volume pot.

2) REMOVE the Ground connection from the Tone pot.

3) CONNECT the Tone pot (where the Ground used to be) to the Volume pot (where the Pink line used to be)

Of course, this would not be installed directly between the Input and Output jacks so you will need to trace the circuit to find out where it needs to be installed 

Good Luck 

[Nicofromfrance]

Hmm, not a good new^^
On this topic http://forum.dijonstock.com/viewtopic.php?f=1&t=10626 the guy did the mod directly between the input and ouput jacks in an extern enclosure, so I thought I could do the same but directly inside the enclosure of the pedal, and between its input and output... my poor skills tricked me  

Maybe the Musikding schematic http://diy.musikding.de/images/stories/factory/factoryschalt.pdf could help finding where to place the mod ?

[Govmnt_Lacky]

I believe that this mod would need to go between R6 and Lug 3 of the Volume pot.

At least... according to the layout that you linked to here:

Maybe the Musikding schematic http://diy.musikding.de/images/stories/factory/factoryschalt.pdf could help finding where to place the mod ?

EDIT: Looking at the layout... it looks like you could test this out very easily by simply disconnecting a few wires and installing the SWTC. Disconnect the wire between Point #7 and Lug 3 of the Volume pot and go from there.

[Nicofromfrance]

EDIT: Looking at the layout... it looks like you could test this out very easily by simply disconnecting a few wires and installing the SWTC. Disconnect the wire between Point #7 and Lug 3 of the Volume pot and go from there.

Now you say it it looks obvious for the beginner I am... Thanks a lot for answers! So I just need to wire point #7 to R1, R1 to lug 3 (left lug) of the added tone pot, wire the new added C1 to lug 2 of the tone pot, and then wire the lug 1 of tone pot (right lug) to the left lug of the volume pot, right? One more thing: concerning C1, I think I can ground it to whatever ground I want, or is there any appropriate ground to it?

I'll try this once I get the components!
Thanks !

[Govmnt_Lacky]

So I just need to wire point #7 to R1, R1 to lug 3 (left lug) of the added tone pot, wire the new added C1 to lug 2 of the tone pot, and then wire the lug 1 of tone pot (right lug) to the left lug of the volume pot, right? One more thing: concerning C1, I think I can ground it to whatever ground I want, or is there any appropriate ground to it?

I'll try this once I get the components!
Thanks !

Not exactly. If you notice, R6 (5K1 resistor) is actually YOUR R1. You don't need to add a resistor. 

Just remove the wire from Volume pot Lug 3 (left lug of pot when looking from the back of it) and connect it to Lug 3 of the Tone pot. Then, connect Lug 1 of the Tone pot to Lug 3 of the Volume pot.

The ground can be any ground in the circuit.

Good Luck 

[joegagan]

fuzzfactory freq response is severely limited by the .01 tant cap between Q1 and Q2. adding an input cap blend at this juncture broadly expands the capabilities of this great pedal. i use a 10 uf as the 'large' cap. i would suggest trying this before any other remedies are implemented.

[Nicofromfrance]

@ Govmnt_Lacky :

So basically I assume this scheme is right?

fuzzfactory freq response is severely limited by the .01 tant cap between Q1 and Q2. adding an input cap blend at this juncture broadly expands the capabilities of this great pedal. i use a 10 uf as the 'large' cap. i would suggest trying this before any other remedies are implemented.

You mean that I should replace the capacitor between Q1 and Q2 by a larger value cap (such as a 10µF) before adding the SWTC and see if it already tames the trebbles?

[Govmnt_Lacky]

Nico,

Yes... your diagram above is correct.

Also, I would highly suggest following Joe's suggestions. He is much more knowledgable about this circuit than I am. 

Good Luck 

[Nicofromfrance]

fuzzfactory freq response is severely limited by the .01 tant cap between Q1 and Q2. adding an input cap blend at this juncture broadly expands the capabilities of this great pedal. i use a 10 uf as the 'large' cap. i would suggest trying this before any other remedies are implemented.

I have a question Joegagan (or anyone else who can help me): I'd like to try your mod by replacing C2 with a tantalum 10µF cap, but I have difficulties to know in which direction to wire it on the PCB. There is a long and a short leg on the cap, I suppose the long one is the + and the short one is the -, but basically I don't know where is the + and the - where the cap goes 

Here is the scheme of the PCB: http://diy.musikding.de/images/stories/factory/factoryschalt.pdf and a picture of my PCB if this might help: The cap to replace is the one marked .1k63



Thanks for help! 

[cthulhudarren]

fuzzfactory freq response is severely limited by the .01 tant cap between Q1 and Q2. adding an input cap blend at this juncture broadly expands the capabilities of this great pedal. i use a 10 uf as the 'large' cap. i would suggest trying this before any other remedies are implemented.

So to implement the blend you would parallel the .01uf with a 10uf in series with say a 500K audio taper pot?

[joegagan]

i like 100k. i was incorrect, the cap between Q1 and Q2 is .1, not .01. regardless, increasing this cap does wonders for the ffactory. keep in mind, anything you have in line between guitar and FFact wil limit low end unless you put Ff first.

[Nicofromfrance]

i like 100k. i was incorrect, the cap between Q1 and Q2 is .1, not .01. regardless, increasing this cap does wonders for the ffactory. keep in mind, anything you have in line between guitar and FFact wil limit low end unless you put Ff first.

I'd like to increase the value of this cap, but only if someone can tell me which direction the 10µF must be soldered    I can't find out in which hole goes the + and the - in the holes that host this cap. my poor knowledge in electronics don't give me any clue 

Thanks a lot!

[cthulhudarren]

i like 100k. i was incorrect, the cap between Q1 and Q2 is .1, not .01. regardless, increasing this cap does wonders for the ffactory. keep in mind, anything you have in line between guitar and FFact wil limit low end unless you put Ff first.

I'd like to increase the value of this cap, but only if someone can tell me which direction the 10µF must be soldered    I can't find out in which hole goes the + and the - in the holes that host this cap. my poor knowledge in electronics don't give me any clue 

Thanks a lot!

If in doubt, you could measure the voltage between the the stage prior and after, and determine polarity by the result.

[Nicofromfrance]

Thanks, I think I'm gonna buy a multimeter now!   

[cthulhudarren]

i like 100k. i was incorrect, the cap between Q1 and Q2 is .1, not .01. regardless, increasing this cap does wonders for the ffactory. keep in mind, anything you have in line between guitar and FFact wil limit low end unless you put Ff first.

Okay, so for your mod, in parallel with the .1u cap, you would wire, in series, a 10u and a 100k pot. Would this pot be audio taper?

Also, for your schematic with the gain mod with the 220k pot, is that also audio taper?

I do like your idea of having two trannies and incorporating a Ge/Si switch for Q1. Does this make the gain mod unnecessary, or would that still be a good mod with this Q1 switch?

So if my counting is accurate, I'm looking at a 7 knob Fuzzfactory with a Ge/Si switch!

[joegagan]

Okay, so for your mod, in parallel with the .1u cap, you would wire, in series, a 10u and a 100k pot. Would this pot be audio taper?

Also, for your schematic with the gain mod with the 220k pot, is that also audio taper?

I do like your idea of having two trannies and incorporating a Ge/Si switch for Q1. Does this make the gain mod unnecessary, or would that still be a good mod with this Q1 switch?

So if my counting is accurate, I'm looking at a 7 knob Fuzzfactory with a Ge/Si switch!

the ability to have a ge first trans does not negate the gain control. they each do their own thing, very nice.

i used lin pots. yes, i do the added 10 uf exactly like you said.

[cthulhudarren]

Okay, so for your mod, in parallel with the .1u cap, you would wire, in series, a 10u and a 100k pot. Would this pot be audio taper?

Also, for your schematic with the gain mod with the 220k pot, is that also audio taper?

I do like your idea of having two trannies and incorporating a Ge/Si switch for Q1. Does this make the gain mod unnecessary, or would that still be a good mod with this Q1 switch?

So if my counting is accurate, I'm looking at a 7 knob Fuzzfactory with a Ge/Si switch!

the ability to have a ge first trans does not negate the gain control. they each do their own thing, very nice.

i used lin pots. yes, i do the added 10 uf exactly like you said.

Joe, where would you recommend that I get the transistors in a similar gain structure as yours? I checked Small Bear (my fav shop) and they don't do gain selection and I wanted the first Q2 ~100 AND Q3 ~130+, low leakage of course, which is similar to your recommendation.

How about Aron's online store here, are they selected for low leakage?

[joegagan]

i am not very aware of small bear's stock of germaniums. the Q2 and Q3 of fuzzfactory pedals i have measured ( circa 2000-ish) were in the 120-130 hfe range, using RG's method. i believe part of the strength of the factory is having good gain on these trannies.

small bear lists an easy face Ge pnp at 130+, you would need two of these.     Transistor - The Easy Face PNP
Old-Stock U.S.-made PNP Germanium Transistor for the Easy Face or other Germanium/Silicon hybrids. Hfe 120-190.
PRICE: $6.00     Shipping Wt. 0.07 oz

for subbing a Ge at Q1, i use an NPN AC187, which is a little below 100 hfe. small bear has NPNs as well.

[cthulhudarren]

i am not very aware of small bear's stock of germaniums. the Q2 and Q3 of fuzzfactory pedals i have measured ( circa 2000-ish) were in the 120-130 hfe range, using RG's method. i believe part of the strength of the factory is having good gain on these trannies.

small bear lists an easy face Ge pnp at 130+, you would need two of these.     Transistor - The Easy Face PNP
Old-Stock U.S.-made PNP Germanium Transistor for the Easy Face or other Germanium/Silicon hybrids. Hfe 120-190.
PRICE: $6.00     Shipping Wt. 0.07 oz

for subbing a Ge at Q1, i use an NPN AC187, which is a little below 100 hfe. small bear has NPNs as well.

Thanks very much, Joe!