# Swiss Army Fuzz: Universal Tone Bender MKII/Fuzz Face Board



## Big Monk

I've just finished putting together the design for a Universal Classic Fuzz board:











It's designed around the Pedal PCB 3 Knob predrilled enclosures from Tayda.

Some of the design parameters:

1.) Power Supply filtering on board, including electrolytic and ceramic caps and protection diode;
2.) Alpha 9mm PCB mount pots;
3.) 1/4W MF resistors, 5.08 mm box caps, 6.3 mm Electrolytics
4.) Can be used to make the Tonebender MK II, Supafuzz, Tonebender MK 1.5 and Fuzz Face
5.) Has optional Rb2 for doing Silicon Tonebenders;
6.) Optional trim pots for collector voltages on Q1, Q2 and Q3;
7.) Optional output trim pot (Rc3a and Rc3b network)
8.) On board ground pads for audio jacks, DC jack, shielded wire shields, and switch ground;
9.) Pads for optional base to collector caps on all three transistors;
10.) Pads are provided for using 3 Pole CUI Term blocks, transistor sockets or hardwired transistor connections.

Any thoughts?


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## Coda

No cup-holder?…


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## Big Monk

I jus


Coda said:


> No cup-holder?…



t wanted to be able to use one board with all the options I can't seem to find in currently produced boards.


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## Feral Feline

Wow!

Nice work! This must've taken a while to sort out all the wee details. Many thanks for sharing

Looks like it will fit 1590B if I do my own drilling.

Self etch or will boards be available for sale?


I think the only way to make the layout stop staring at me is to build it, poke out its eyes with the centre pot.


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## Big Monk

Feral Feline said:


> Wow!
> 
> Nice work! This must've taken a while to sort out all the wee details. Many thanks for sharing
> 
> Looks like it will fit 1590B if I do my own drilling.
> 
> Self etch or will boards be available for sale?
> 
> 
> I think the only way to make the layout stop staring at me is to build it, poke out its eyes with the centre pot.



I sent away for 5 boards from JLCPCB today. I need 3 and could definitely part with the other 2.


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## Feral Feline

I'm down for 1


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## Big Monk

Feral Feline said:


> I'm down for 1



One of the things I did was have the pads for external wire connections available on both sides. That way, when you get the pots soldered in, you can mount all the other components AND mount the board and solder all wires in from up top.


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## Feral Feline

You've given a LOT of thought to your creation! Kudos.


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## Big Monk

Feral Feline said:


> You've given a LOT of thought to your creation! Kudos.



Here’s hoping it works!


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## Feral Feline

🤞


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## finebyfine

Absolutely mindblowing. Looks awesome, and I want one.

Which pads are the grounds for jacks/dc/switches? I’m guessing its the larger ones the 4 on top and two in the middle. I personally would do all offboard connections as a row or two of 2.54mm pitch pads so people could have tidier offboard wiring with ribbon wire (or even use my trademark favorite: 2.54mm screw terminals 😉)

edit: oh those are for the 9mm pots arent they

you could also go even more overkill on the transistor options and add SOT-23 pads


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## Big Monk

finebyfine said:


> Which pads are the grounds for jacks/dc/switches? I’m guessing its the larger ones the 4 on top and two in the middle. I personally would do all offboard connections as a row or two of 2.54mm pitch pads so people could have tidier offboard wiring with ribbon wire (or even use my trademark favorite: 2.54mm screw terminals 😉)






My thought process behind laying out the I/O was that I personally like to be able to send the various grounds and I/O to the board as close to the components they are coming from as possible. To me that's neater. 

If you can visualize what this would look like in a PedalPCB, pre-drilled 125B with top jacks, the following would happen:

1.) Shielded wire from the input jack will go to the switch, hugging the side of the enclosure, and then another shielded run comes back from the switch, again hugging the side (these can be secured together with a zip tie mount low in the enclosure) and landing on the 2 pads provided in the top left corner;

2.) Jack and DC grounds land with a very short run at the top of the board;

3.) Your switch ground lands with a short run at the bottom of the board;

4.) Output shielded wire has the same journey as the input on the opposite side of the board.

This is a pretty good grounding setup ala R.G. Keen when you use an isolated output jack and avoid power switching on the input. In this case, since the Pedal PCB enclosure does not support a battery anyway, for PNP or Battery power, you can simply sub the DC Jack for an ON/OFF battery switch and always use a mono Input Jack and make sure it makes good contact with the enclosure for shielding.


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## finebyfine

Makes sense! Really interesting to see the thought process


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## Big Monk

finebyfine said:


> Makes sense! Really interesting to see the thought process



At the end of the day, it was about having a single board, with all the options, so that I could build Tonebender MK II types and Fuzz Face types without multiple designs.


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## Big Monk

Boards are in!


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## Harry Klippton

Those look snazzy in flat black


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## Big Monk

Harry Klippton said:


> Those look snazzy in flat black



I wanted something with the aesthetic of the old fuzz boards but with the construction of a PCB.


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## Big Monk

Did some dry fitting this morning:









The only things I’ll change on the next revision are the following:

1.) Provide another pad for the collector to base caps. My measurements were for the small monolithic lead spacing and not the wider yellow ceramics from Tayda. Not a deal breaker as I was able to bend them to sit flush down on the board. 

2.) Provide more pads for the trim pots to accommodate the non-cermet types. You can see in the second picture I had to bend those legs in a little. 

3.) Move the ground pads for the input/output jack sleeves. The PCB pot has a support leg on the back that is deirectly over the pad. It has no connection to the pot itself so there is no shorting issue here, but a better location is just to the right and left of each.


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## caiofilipini

Looks super cool! Out of curiosity, how did you make those pads that are only plated on one side of the board?


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## Big Monk

caiofilipini said:


> Looks super cool! Out of curiosity, how did you make those pads that are only plated on one side of the board?



In DipTrace, you right click the pad and select "Hide Ring in Pad Layer"


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## caiofilipini

Looks like I'm gonna have to give DipTrace a shot. I googled how to do that in Eagle and couldn't really find anything useful or easy enough a dumb like me could understand.

Thanks!


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## Big Monk

caiofilipini said:


> Looks like I'm gonna have to give DipTrace a shot. I googled how to do that in Eagle and couldn't really find anything useful or easy enough a dumb like me could understand.
> 
> Thanks!



I tried the other e-cad softwares and they are way over my head. DipTrace let’s me do dunceski manual routing.


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## Big Monk

Here are the mockups of my Tonebender, Ge Fuzz Face and Si Fuzz Face using this board:







Inside is going to be very tight. If I had it to do again, I’d have used right angle alpha PCB pots ala Pedal PCB. I’ll still be fine but the jacks are sitting ready get on top of the board.


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## Big Monk

After doing a mock-up last night with the 9mm Alpha PCB pots on the board, I decided I’m going to put in another order to JLCPCB so that I can use normal 16mm Alpha PCB mounted pots al Pedal PCB. 

I was going to have clearance issues to the jacks and I’m not comfortable with how much stress the pots need to be subjected to to mount in the enclosure. I’m not sure if I was off just a touch with my pad placements but things are not lining up as easily as I would have like and the 16mm pots will give me more play.


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## Big Monk

Okay.

So I was able to get the prototype wire up today. I purposely used leftover parts and whatever else I had because I did not want to waste parts if the circuit did not work.

I also chose to use flying leads off the board and no mechanicals so I could just set it on top of my 1590DD breadboard environment and use the built in switching and mechanicals from that.

Fire it up and Viola! Worked first time. I’ll post some pictures shortly but this is good news for the 3 builds I have planned.

Only error I made in the layout (and that I missed on the latest iteration coming from JLCPCB with the 16mm RA PCB pot pads) is that I have all the power filtering upstream of the power input pad. Dummy move but a very small drill hole will allow me to tap upstream of the filter cap and tie it in there.


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## Big Monk

Pots are mount on top so the travel is backwards. I have all the trim pots installed but I’m not sure I will for full build outs. I also don’t think the term blocks will go in the finished builds but I haven’t decided yet. 

I didn’t install base to collector ceramics because I have a low inventory of the values I need for the next three builds but they can just get jumped into the term blocks for testing.


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## Big Monk

So, I think a final revision will be in order and I’m thinking of offering the base design to @PedalPCB 

I’ll use my incoming boards with the modification to the power supply input for my own circuits. Everything in the design functions perfectly. All three collector trims work great, the trim on the Rc3a and Rc3b string allows you to dial in output volume, etc. 

I’ll type up some notes and installation manual and maybe this board can hit the big time.


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## Big Monk

In the continuing saga of the Universal Fuzz Board: Got the new crop of 5 boards in today and they were Green! Dang. Seems like a silly thing to be upset about but these are better looking in Black.

So, I am going to correct a few errors that were outstanding, add collector voltage test pads, and add extra pads for caps that can be either electros or film.


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## Big Monk

Finalized boards are in!


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## Harry Klippton

Wow uh, white socks, huh. Board looks great!


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## Big Monk

Starting populating the components I’m sure about, i.e. resistors, trimmers, power supply filtering and B-C caps:


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## Big Monk

Did some prep work tonight, including wiring the DC jack, LED and part of the switch. 

Mocked it up:


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## Chris420

Big Monk said:


> Did some prep work tonight, including wiring the DC jack, LED and part of the switch.
> 
> Mocked it up:
> 
> View attachment 15630View attachment 15631


Nice!!


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## Big Monk

Full volume testing occured today and the cap choices are finalized!:

Cin = 6.8 uf
Cout = 0.01 uf
Ctb = 0.0027 uf
Cbc1 = 470 pf
Cbc2 = 200 pf
Cbc3 = 200 pf

Going to wire them in tonight and prep my 4 shielded wire runs.


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## Big Monk

First Universal Fuzz board build is in the books! This one is a Tonebender MK II:








She’s a screamer. I have enough travel on the trim pots to go from about 7.7-8.2 vDC on Q1 and Q3.

I may tweak Rc2 to try and get a touch more range on the lower end (7.5 ish) for Q3.


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## Big Monk

So, after a few days of messing around with this, I realized that the B-C caps on all three transistors did NOT reduce the high end as much as I perceived at low volume. Cranking it up the past few days has shown it to be a touch ragged and brittle in the high end. Furthermore, reducing Ctb (treble bleed cap on the input) down as low as i did has also promoted the pedal slipping into feedback a bit to easy, and if I'm being honest, shrilly for my tastes.

Tonight some time I think I'll go in and make a few changes:

1.) Change out the fixed side of the Rc2 resistor/trimmer string with 47k and expand the range of the control.
2.) Swap Ctb back to 0.01 uf
3.) Change Ce back to 4.7 uf 

After a few more days of testing, i should have a better idea if that's good enough. Worst case scenario, if the pedal needs some more "ass", I'll swap in a 10 uf for Cin.

In related news, Silicon Fuzz Face breadboarding is underway. I was having some issues with oscillation and while I'm not 100% satisfied yet, a 2200 pF capacitor across the feedback resistor squashed it without affecting the high end too much. It's a work in progress, as I am trying to balance my Strat with humbuckers (humbuckers a bit lower than my LP and guitar a bit snappier) with my Les Paul (humbuckers at "normal" heights, fuller sounding) and the Fuzz Face can be notoriously wooly.


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## Big Monk

Changed out a few caps and fixed my Q2 collector resistor:






Disclaimer: I am not responsible for any damage and/or injury cause by my bad playing.


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## Feral Feline

Didn't realise you were a _Titanius Giganticus_

Great-sounding FuZz.


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## Big Monk

Feral Feline said:


> Didn't realise you were a _Titanius Giganticus_
> 
> Great-sounding FuZz.



Thank you!

I spend a great deal of time tuning these before boxing them up. Plus, I’ve been testing and tweaking Mk II circuits on the breadboard for a few years now.


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## Big Monk

Round 2! The silicon Fuzz Face is in the books!:


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## Feral Feline

I haven't got any experience with Ge, really, 'cause when I hear silicon on bass, it triggers me in the right way.


Looking forward to hearing this next build!


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## fig

It sounds fantastic!


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## Big Monk

Another one in the books Gang!

This time. Germanium Fuzz Face using the same GE 2N169 units. Here is a shot showing how I prep the LED, switch and power jack connections:







Here is the external shot and the finished interior:


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## Big Monk

I had to tweak the Tonebender MK II today. At full volume, it was getting a little farty and I wanted this to be a Rhythm cruncher as well as lead tone. 

I dropped the emitter cap from 4.7 uf to 2.2 uf and the treble bleed cap on the input from 0.01 uf to 0.0082 uf. 

Then shit got screwy because I also needed to give myself more range on the Q1c trimpot and when I removed the fixed resistor for R1c, I lifted the pad connecting it to the trimpot! I was able to jump the lead over to the trim but I think I better call this one good for now!


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## Big Monk

Big Monk said:


> Round 2! The silicon Fuzz Face is in the books!:
> 
> View attachment 15887View attachment 15888



This baby is going in for surgery next week! Some frequency related tweaks. Input cap and emitter cap are going down a bit.


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## Big Monk

Opened this baby up today and surprisingly did not have to change much.   

I had originally thought I went with a 1 uf/10 uf input cap/emitter cap combo. 

Turns out it was 1 uf/22 uf. 

Since I was just trying to round off a touch more woof, I went with a 0.82 uf input cap. 

Plugged it in today and it did the trick! Not a huge difference but noticeably less woof at full Fuzz and Pre-gain settings.


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