# Design Challenge #1



## Chuck D. Bones (Oct 31, 2020)

We've read posts here where someone says "I've got this part and I want to figure out what to do with it.  How would I design this into a pedal?"  Usually the design process works the other way, but there's no reason not have a bit of fun and try to design something around specific parts.  It's the accidents and out-of-the-box thinking that spawn new and creative designs.

So here's the challenge.  Design a pedal using this part:

https://www.goldmine-elec-products.com/prodinfo.asp?number=G25209

It's a B20K 4-gang pot.  The only rules are that every gang must be used and they must all do something useful.


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## dlazzarini (Oct 31, 2020)

Chuck D. Bones said:


> We've read posts here where someone says "I've got this part and I want to figure out what to do with it.  How would I design this into a pedal?"  Usually the design process works the other way, but there's no reason not have a bit of fun and try to design something around specific parts.  It's the accidents and out-of-the-box thinking that spawn new and creative designs.
> 
> So here's the challenge.  Design a pedal using this part:
> 
> ...


I’ll have to come back to this after I read through some of the theory articles you promised to post. Looking forward to it.


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## Chas Grant (Oct 31, 2020)

This might actually work. Might have to breadboard it after figuring out actual values for resistors and caps. As is, all resistors and caps are arbitrary, starting points if you will. Nothing was calculated so... But the premises is as you increase the gain on Q2 and Q3 you also change the base bias voltage causing Q2 to shift up and hard clip the top of the signal and Q3 to shift down and hard clip the bottom of the signal. It may be kinda harsh though. Also I do not have a 4 gang pot symbol so I used a dual gang pot twice and gave it the same name. And R3 may need to be tied to +9Vdc, I was just having fun with VAA.


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## Chuck D. Bones (Oct 31, 2020)

Very clever!


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## Barry (Oct 31, 2020)

I don't think I'm quite there yet! Maybe next time


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## Chuck D. Bones (Nov 1, 2020)

I tried ganging together the tone controls in a TMB stack, but could not find an interesting combination.  

Here's an idea: stack four clipping stages, each with a gain control and gang all four gain controls together.  Make each stage different, some hard clipping, some soft clipping, some symmetric, some asymmetric, different bass & treble rolloff in each stage, etc.  As the gain is turned up, more and more of the clippers come into play.  Kinda like an M I Audio Tube Zone, but with four stages instead of two.


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## Markus Kersius (Nov 1, 2020)

Chuck D. Bones said:


> I tried ganging together the tone controls in a TMB stack, but could not find an interesting combination.
> 
> Here's an idea: stack four clipping stages, each with a gain control and gang all four gain controls together.  Make each stage different, some hard clipping, some soft clipping, some symmetric, some asymmetric, different bass & treble rolloff in each stage, etc.  As the gain is turned up, more and more of the clippers come into play.  Kinda like an M I Audio Tube Zone, but with four stages instead of two.


 This could work in a Big Muff circuit then.


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## music6000 (Nov 1, 2020)

Be aware,  the 4 gang potentiometer body measures just over 17mm in height, A standard 16mm with dust cover is around 10mm.
16mm PCB Long leg pots will have to be implemented if a PCB style board is used.


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## Chas Grant (Nov 1, 2020)

music6000 said:


> Be aware,  the 4 gang potentiometer body measures just over 17mm in height, A standard 16mm with dust cover is around 10mm.
> 16mm PCB Long leg pots will have to be implemented if a PCB style board is used.


Naw Man! Just horizontal mount this bad boy, have it sticking out the left side of the enclosure and put a 4 foot stick shift on it, Wah pedal to the right of the enclosure, and give a whole new meaning to the "drive" part of overdrive!


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## zgrav (Nov 1, 2020)

Might be interesting to design the pots so a rotation will increase gain on  one or two points while decreasing gain on the others.  Then it could be a see-saw adjustment rather than raising or lowering all of the gains at the same time.


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## music6000 (Nov 1, 2020)

Chas Grant said:


> Naw Man! Just horizontal mount this bad boy, have it sticking out the left side of the enclosure and put a 4 foot stick shift on it, Wah pedal to the right of the enclosure, and give a whole new meaning to the "drive" part of overdrive!


Here's a stick shift on my Hot Wired Distortion with Blend knob Mod from 2017!
I built 3 -  Dual, Drive & Distortion versions :


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## Chas Grant (Nov 1, 2020)

music6000 said:


> Here's a stick shift on my Hot Wired Distortion with Blend knob Mod from 2017!
> I built 3 -  Dual, Drive & Distortion versions :
> View attachment 7478
> View attachment 7479



WOW!! That is really nice! The stick shift is like the cherry on top!


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## Chuck D. Bones (Nov 2, 2020)

music6000 said:


> Here's a stick shift on my Hot Wired Distortion with Blend knob Mod from 2017!
> I built 3 -  Dual, Drive & Distortion versions :
> 
> View attachment 7478
> View attachment 7479


I always have to see the inside of Music6000's pedals.
1. The rivet board construction is beautifully crafted.
2. His photoshop skills make me wonder whether the pedal is real or imagined.

*WARNING! * Duracell batteries are leakers and will puke electrolyte all over the inside of your precious pedals.


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## Chuck D. Bones (Nov 2, 2020)

music6000 said:


> Be aware,  the 4 gang potentiometer body measures just over 17mm in height, A standard 16mm with dust cover is around 10mm.
> 16mm PCB Long leg pots will have to be implemented if a PCB style board is used.


It was mainly a thought experiment, but the pot body is short enough to fit inside a 125B box.  The board, or at least part of it, could be perpendicular to the front panel.


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## music6000 (Nov 2, 2020)

Chuck D. Bones said:


> I always have to see the inside of Music6000's pedals.
> 1. The rivet board construction is beautifully crafted.
> 2. His photoshop skills make me wonder whether the pedal is real or imagined.
> 
> *WARNING! * Duracell batteries are leakers and will puke electrolyte all of the inside of your precious pedals.


Here you go Chuck, Here's the '' Hot Wire '' Dual Pedal I Built!


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## music6000 (Nov 2, 2020)

*WARNING! *Duracell batteries are leakers and will puke electrolyte all of the inside of your precious pedals.
I only use Batteries for demonstration purposes!!!
None of my pedals have Batteries, It's just an option for those that like to use them.


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## Chuck D. Bones (Nov 2, 2020)

music6000 said:


> Here you go Chuck, Here's the '' Hot Wire '' Dual Pedal I Built!


Can we see a schematic?  Pretty please?


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## Chas Grant (Nov 2, 2020)

And where do you get the boards from, they RULE!


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## Chuck D. Bones (Nov 2, 2020)

He makes 'em from scratch.


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## music6000 (Nov 2, 2020)

Chas Grant said:


> And where do you get the boards from, they RULE!


I purchased a 1 metre x 600mm (3 foot, 3 inches x 2 foot) offcut of 2mm FR-4 around 7 years ago & Design, cut, drill & 2.5mm Eyelet every one to suit the Build.
I have a 2mm thick aluminium drilling template that I use to drill up to 16 / 1.6mm holes for Op Amp sockets.
I twist 24 awg insulated pre tinned wire around a dress makers pin twice & slide it over Socket pin and solder in place to hold socket firmly in place and to edge of appropiate Eyelet.


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## music6000 (Nov 2, 2020)

Chuck D. Bones said:


> Can we see a schematic?  Pretty please?


I used the Layout from here & added the  Split & Blend circuit to it :








						Wampler Hot Wired v.1
					

Collection of vero (stripboard) & tagboard layouts for 100s of popular guitar effects, with over 500 verified designs. DIY your own boutique effects!




					tagboardeffects.blogspot.com


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## Chas Grant (Nov 2, 2020)

music6000 said:


> I purchased a 1 metre x 600mm (3 foot, 3 inches x 2 foot) offcut of 2mm FR-4 around 7 years ago & Design, cut, drill & 2.5mm Eyelet every one to suit the Build.
> I have a 2mm thick aluminium drilling template that I use to drill up to 16 / 1.6mm holes for Op Amp sockets.
> I twist 24 awg insulated pre tinned wire around a dress makers pin twice & slide it over Socket pin and solder in place to hold socket firmly in place and to edge of appropiate Eyelet.


OH SNAP!! That's a lot of work, but the end result is absolutely ASTONISHING!


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## Chuck D. Bones (Nov 3, 2020)

A few other things to do with a 4-gang pot...

Make two separately tuned active filters.  One goes up, the other goes down when the pot is rotated clockwise.  Wire the filters in parallel with a blend knob. 

Make four separately tuned Cry-Baby type filters, two pairs in series and then the series pairs in parallel with a blend knob.

Make four LFOs, with the four-gang pot as the speed control.  Tune them all differently and mix their outputs for a chaotic control voltage for a filter or phaser.

Make four LFOs, with the four-gang pot as the speed control.  Tune them all differently and wire their outputs to separately control each stage in a four-stage phaser.

Wire the four-gang pot into a Honey Bee type overdrive as the ultimate NATURE control.  Lotta places to vary the tone!


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## benny_profane (Nov 3, 2020)

@Chuck D. Bones You've mentioned that many LFO circuit blocks are poorly designed. Would you mind adding some information about LFOs to the boneyard?


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## Chuck D. Bones (Nov 3, 2020)

Good idea... I could do that.


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## HamishR (Nov 6, 2020)

I'm not so sure about this. My mum always warned me off gangs.

BTW a lot of older handwired Menatone pedals are built very much like Music 6000's pedals - except Brian Mena used some kind of perforated board (no solder pads) that he hammered eyelets into. The eyelets are the same things that Fender tagboard circuitboards use. Places like Mojotone sell the eyelets and the little punch you need to mount them to the board. To me it's a wondrous thing to behold but looks like so much work!


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## jubal81 (Nov 7, 2020)

My first thought was to use it as a 'width' adjustment on a 4-stage phaser. 20K too low for that, though.

Another idea would be to pair it with a 2p4t switch to choose among 4 tone stacks.


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## jubal81 (Nov 28, 2020)

Got another gain machine for this.

I'm a certified JFET junkie, so I went with the MuAmps for a cranked-amp OD thing.
Pots 2&3: boosts gain on both clipping stages with source bypass caps
Pot 1: Cuts a bit of treble as gain goes up to tame harsh top end
Pot 4: Clean blend

The second opamp is the mixing stage with a volume strapped on there for boost or cut, and then I followed with a stupidly wonderful tone control. 

Drew this off the top of my head, so a lot of the values are just guesses.


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## Chuck D. Bones (Nov 28, 2020)

Interesting!  I should have something presentable in the next day or two.  I've found that when using a B-taper pot for a gain control, I need series a resistor that is at least 5% of the pot value.


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## Chuck D. Bones (Dec 1, 2020)

Ta-Da!  I ended up breadboarding two very similar versions of this circuit (see below).  It started out as 4 gain stages, with hard diode clippers and a volume recovery stage at the end.  Way too unruly.  Cut back to 3 gain stages, similar to what you see here, still had the hard diode clippers and a volume recovery stage.  Decided I didn't like the hard clipping, so I removed the diodes (they were in parallel with C9).  The signal was much larger without the diodes, so I ditched the volume recovery stage.  The first version had all Si BJTs.  Then I tried some Ge transistors for the 2nd & 3rd stages.  Didn't really hear a difference.  When back to Si and switched to JFETs for the input and gain recovery stages, mainly to reduce the parts count.  I finally settled on V2.3 below.  Tried Ge once more for the last stage, no real sonic diff, then a MOSFET.  The MOSFET does sound a little different, hard to describe.  Tried tuning the TONE control for mid hump, mid scoop and flat in the middle.  Ended up with flat.  Treble boost is fairly mild and starts in the midrange.  Treble cut smooths out the hair without getting too dark.  I also played around with the coupling capacitors (C3 & C6).  The ones in there now let some bass thru without getting too muddy.  If you want sludge or some deep bottom-end for playing bass thru it, then increasing C3, C4  & C6 will get you there.

Development tools I used were Duncan's Tone Stack Calculator, LTSpice, breadboard, USB scope, headphones and a Strat.  Oh, and a big pile of parts.

Here's how it all works:
The first three sections of the FUZZ control (VR1) varies the gain & bias on each stage.  The last section of the FUZZ control (VR1D) is a Presence control that cuts back the top end as the gain is turned up.  Because VR1 is all linear taper pots, I had to install series resistors smooth out the gain variation at the low end of the resistance range.  The FUZZ control is very smooth now and goes from clean at 7:00 to mild overdrive around 10:00 and gets progressively nastier from there.  Total gain adjustment range is 40dB.  The TONE control is similar to the Foxx Tone Machine, just tuned differently.  Basically a BMP tone control with one resistor removed.

1st stage is a simple JFET boost, with a variable drain resistance to adjust the gain and headroom.  Has a little over 30dB gain with FUZZ dimed.  C2 rolls off the top end a little at max FUZZ.  Most JFETs will work, you can compensate for different Vp by adjusting R5.

2nd and 3rd stages are very similar to the Quarantine Fuzz.  Their gains and bias points are adjusted via the pots in their emitter paths.  R9 & R14 limit the max gain; R13 limits the min gain.  Any high-gain, low noise NPN transistors will work.  Any N-channel MOSFET will work for Q3 in ver 2.4; tune the bias range with R11.

Is it a great pedal?  It's OK, it's no Mojito or Biggus Dickus.  I'll probably end up making a Vero and stuffing it in a Handy Box just for fun.  It's been a fun diversion during lockdown.


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## Chas Grant (Dec 1, 2020)

Golly Gee Wally, that is pretty nifty!   

Actually its really cool. Pulling something out of your head and getting it onto breadboard and working is a good feeling! I bet you can tweak some values to get it sounding real good.


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## Chuck D. Bones (Dec 1, 2020)

Chas Grant said:


> I bet you can tweak some values to get it sounding real good.



I've been tryin'.


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## jubal81 (Dec 1, 2020)

Looking cool. I'm surprised the Ge trannies didn't sound much different. That's pretty interesting.
Does the Mosfet give a more aggressive, tighter sound?


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## Chuck D. Bones (Dec 1, 2020)

I was surprised too.  It's hard to compare Ge, Si & MOSFET in this circuit because I can't rapidly switch between them.  All I can say for sure is there was nothing striking about any of them.  Maybe when I get it dialed in better...


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## music6000 (Dec 1, 2020)

It might need a FAT switch, Ha Ha!


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## Chuck D. Bones (Dec 1, 2020)

<(-.-)>
Funny you are, hmmm?


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## Ratimus (Dec 1, 2020)

Chuck D. Bones said:


> Ta-Da!  I ended up breadboarding two very similar versions of this circuit (see below).  It started out as 4 gain stages, with hard diode clippers and a volume recovery stage at the end.  Way too unruly.  Cut back to 3 gain stages, similar to what you see here, still had the hard diode clippers and a volume recovery stage.  Decided I didn't like the hard clipping, so I removed the diodes (they were in parallel with C9).  The signal was much larger without the diodes, so I ditched the volume recovery stage.  The first version had all Si BJTs.  Then I tried some Ge transistors for the 2nd & 3rd stages.  Didn't really hear a difference.  When back to Si and switched to JFETs for the input and gain recovery stages, mainly to reduce the parts count.  I finally settled on V2.3 below.  Tried Ge once more for the last stage, no real sonic diff, then a MOSFET.  The MOSFET does sound a little different, hard to describe.  Tried tuning the TONE control for mid hump, mid scoop and flat in the middle.  Ended up with flat.  Treble boost is fairly mild and starts in the midrange.  Treble cut smooths out the hair without getting too dark.  I also played around with the coupling capacitors (C3 & C6).  The ones in there now let some bass thru without getting too muddy.  If you want sludge or some deep bottom-end for playing bass thru it, then increasing C3, C4  & C6 will get you there.
> 
> Development tools I used were Duncan's Tone Stack Calculator, LTSpice, breadboard, USB scope, headphones and a Strat.  Oh, and a big pile of parts.
> 
> ...



Now you got me thinking about four gain stages like you originally had, but with reverse beta transistors like in a Fuzz War...


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## BurntFingers (Dec 1, 2020)

I was just thinking a tl074 with each op amp wired to a gain pot. Have each stage amplify a certain frequency range, like 400-800hz, 600-1000hz, 720-1200hz, 1khz-2.2khz. Soft clipping all the way with green LEDs, then red LEDs, then 1n4001s, then 4148s all in pairs in the feedback loop of each stage respectively.

Vary the input resistors to reduce the gain as you go through the circuit and you might have something approaching usable at the end.

I made a circuit using a dual gang along similar lined and it works amazingly well, no reason why a quad gang can't make it betterer because more is more right?

Call it the Gang Bang. Job done.


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## Chuck D. Bones (Dec 1, 2020)

Can you sketch something up?


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## Chuck D. Bones (Dec 1, 2020)

Here's an update.  This sucker is sounding waaaaaay better.  The BJT 2nd stage was too harsh.  Changing to a JFET smoothed out the tone.  Went back to a Ge 3rd stage.  Q3's leakage is very low and the hFE is around 140.  I think it's very close to done.  Need to spend some more time playing thru it to see if the TONE control range is acceptable.


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## BurntFingers (Dec 1, 2020)

Chuck D. Bones said:


> Can you sketch something up?


Yeah probably if I can find an eagle library part for a 4 gang pot. But it'll be a while as I'm neck deep in trying to sort out this bi-color led thing that is sadly kicking my ass (see post in the modifications section).

One thing about stacking gain stages this way is you've gotta keep the gain levels low as I think they're exponential. So even a gain stage of 10, which is pretty mild, across every stage night be too much and feedback since it'll be 10x10x10x10 (I think so at least).


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## Chuck D. Bones (Dec 2, 2020)

Yup.  10x = 20dB.  Gains multiply, dBs add.  Comes to the same thing.  10x10x10x10 = 80dB.  
To put it in perspective, low-gain distortion pedals, like the Crystal Drive, are around 40 to 50dB.  BMPs are around 70 to 80dB.  Biggus Dickus is around 90dB.  Covert is around 100dB.  SoFTii is over 125dB in Stoner mode.  Thermionic and Revv G pedals are in similar territory.


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## BurntFingers (Dec 2, 2020)

10⁴ is 10,000. That's what I was wondering.


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## Chuck D. Bones (Dec 2, 2020)

For my schematic, I just drew four single pots and gave them the same ref des.  Since I'm not routing a board, I didn't need a symbol for a 4-gang pot.  

To your point, 10,000 is not too much gain for a dirt pedal.  I simulated the Fuzz War v1 and it runs about 20dB per stage.  For whatever reason, DBA likes running transistors in reverse-beta mode.  They still work, but the hFE is very low.


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## Chuck D. Bones (Dec 2, 2020)

This morning's update...

1.  Added a 2.2nF cap from LEVEL pin 3 to GND.  Shaves just a little off of the top end.

2.  Swapped Q3 out for a leaky, low hFE MP38A.  No difference in performance.  Conclusion: this circuit is not sensitive to transistor parameters and just about any NPN Ge will work.  Makes sense because the bias circuit is robust and Q2 can easily drive Q3 into cutoff and saturation.

I nicked my left index finger with an exacto knife 3 days ago and it's almost healed.  I'll be able to give this bitch a proper workout in a day or two...


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## music6000 (Dec 2, 2020)

Chuck, Do you mean something like this?


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## Chuck D. Bones (Dec 2, 2020)

It's like Deja Vu all over again!


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## Chuck D. Bones (Dec 4, 2020)

music6000 said:


> It might need a FAT switch, Ha Ha!


You might be right.  I've identified two places in the circuit where a FAT switch could be easily implemented.  Hmmm, more testing...


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## music6000 (Dec 4, 2020)

Chuck D. Bones said:


> You might be right.  I've identified two places in the circuit where a FAT switch could be easily implemented.  Hmmm, more testing...


*CH* lettering hiding behind Footswitch!


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## Chuck D. Bones (Dec 4, 2020)

Saw that!  Is part of the 2nd word obscured by the switch?


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## music6000 (Dec 4, 2020)

Chuck D. Bones said:


> Saw that!  Is part of the 2nd word obscured by the switch?


Could Be!


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## music6000 (Dec 4, 2020)

Chuck D. Bones said:


> This morning's update...
> I'll be able to give this bitch a proper workout in a day or two...


Reference!


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## Chuck D. Bones (Dec 6, 2020)

Pursuant to Music6000's recommendation, I have added a FAT switch and it works!  Huge bottom end sludge with FAT engaged.  Either way, this pedal sounds great. Definitely going to build a Vero.  I added C15 & S2, bumped up C7 a little bit.  The schematic shows 2N1308 for Q3, but I'm still running an MP38A there.  Makes a great AC/DC sound.


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## music6000 (Dec 6, 2020)

Chuck D. Bones said:


> Pursuant to Music6000's recommendation, I have added a FAT switch and it works!  Huge bottom end sludge with FAT engaged.  Either way, this pedal sounds great. Definitely going to build a Vero.  I added C15 & S2, bumped up C7 a little bit.  The schematic shows 2N1308 for Q3, but I'm still running an MP38A there.  Makes a great AC/DC sound.
> 
> There's no denying it, That is definately a *FAT* switch!!!


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## Chuck D. Bones (Dec 10, 2020)




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## music6000 (Dec 10, 2020)

Chuck D. Bones said:


> View attachment 8340
> 
> View attachment 8341


I love your use of multiple components for a change of colour that do the same job!


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## Chas Grant (Dec 10, 2020)

It's a rainbow of components!


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## Chuck D. Bones (Dec 10, 2020)

The Chef will use whatever is in the pantry.


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## Chas Grant (Dec 10, 2020)

As any great chef would


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## Chuck D. Bones (Dec 11, 2020)

Finished assembly, next comes the painting.  LEVEL & TONE on the bottom, FUZZ in the middle, FAT upper right.  I changed C11 to 10nF and C12 to 4.7nF in an effort to give to the TONE control a little more range and a slight mid scoop when TONE is above noon.


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## music6000 (Dec 11, 2020)

Chuck D. Bones said:


> Finished assembly, next comes the painting.  LEVEL & TONE on the bottom, FUZZ in the middle, FAT upper right.  I changed C11 to 10nF and C12 to 4.7nF in an effort to give to the TONE control a little more range and a slight mid scoop when TONE is above noon.
> 
> View attachment 8363
> 
> View attachment 8364


The Bolt is a bit off an overkill to hold the Board!


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## Chuck D. Bones (Dec 11, 2020)

music6000 said:


> The Bolt is a bit off an overkill to hold the Board!


After reading that, I had to check to make sure the bolt wasn't touching the board! ?


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## cooder (Dec 11, 2020)

That is some crazy good stuff there...


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## Chuck D. Bones (Dec 11, 2020)

Thanks, Man. Trying to come up with a name for it...


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## music6000 (Dec 12, 2020)

Quadra Fuzz?
Quad Fuzz?


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## Chuck D. Bones (Dec 12, 2020)

How about 4Q?


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## jubal81 (Dec 12, 2020)

4 Loco

Keeps with the beverage theme, lol.


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## Chuck D. Bones (Dec 12, 2020)

jubal81 said:


> 4 Loco
> 
> Keeps with the beverage theme, lol.


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## Chuck D. Bones (Dec 30, 2020)

I have a name: *Angry Smurf*.  You can look up the recipe. 
I sold the first one to a friend of mine.  He wanted the box left bare for the industrial look. 
This afternoon I added a BIAS control on the breadboard.  It varies the bias on the 2nd stage to change the voicing and at the extreme end, produces a sputtering gated tone.  The next build will be in a 125B enclosure (blue of course).  Should have it done by the weekend.


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## music6000 (Dec 30, 2020)

Chuck D. Bones said:


> I have a name: *Angry Smurf*.


*Update:* Fat switch stragetically added :


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## Chuck D. Bones (Dec 30, 2020)

Almost Perfect!  Just needs the FAT switch, strategically located.


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## music6000 (Dec 30, 2020)

Chuck D. Bones said:


> Almost Perfect!  Just needs the FAT switch, strategically located.


Done!!!, I wasn't messin' with the *Angry Smurf!*


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## Chuck D. Bones (Jan 4, 2021)

And here it is, the Angry Smurf!

Top row: TONE, BIAS
Middle: FAT switch
Bottom row: LEVEL, FUZZ

I intended to put FUZZ on the upper right, but the 4-gang pot is too tall to clear the input jack.









The only change from the previous version was the addition of the BIAS pot.  With BIAS at zero, it behaves the same as the previous version.  Turning the BIAS up varies the harmonic structure.  It's most apparent at lower FUZZ settings.  With BIAS dimed, Q2 saturates and we get the gated, velcro fuzz sounds.

Final schematic:


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## BurntFingers (Jan 4, 2021)

With c13 going to ground there, that's forming a low pass filter with vr2 right?


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## Chuck D. Bones (Jan 4, 2021)

BurntFingers said:


> With c13 going to ground there, that's forming a low pass filter with vr2 right?



Correct.  C13 shaves a little more hair off of the high end.  When TONE is at zero, C13 takes off about 2dB above 2KHz.  With TONE at noon, it takes off 2dB at 3KHz and 6dB at 10KHz.  With TONE dimed, it takes off 2dB at 1.5KHz and 4dB at 10KHz.  C13's effect is audible, but not overly dark.  I actually located C13 on the LEVEL pot to simplify wiring a bit.

The one I built for my friend had C10 = 10nF and C11 = 4.7nF.  TONE had a little more range and a slight mid scoop in the middle.


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## BurntFingers (Jan 9, 2021)

Hey Chuck, with this pedal do you notice a filtering when you turn the volume knob down? I've got a pedal that ends in a big muff style tonestack then out through a volume pot, just like you have except I opted for a 4.7n to gnd a while ago. But when I roll the volume back the bass dries up and I'm having trouble finding out why.


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## Chuck D. Bones (Jan 9, 2021)

I have not noticed it, but I'll try having another listen.  Three things happen when you rotate the volume control on your pedal.  
1. The volume changes - this is the desired effect.
2. The output impedance of the pedal changes - this can affect the behavior of the next device in the chain.
3. The loading on the pedal's tone network can change, depending on the input impedance of the next device in the chain.

There are ways to deal with all of this, but we need a better understanding of the bigger picture.  Pedal circuits can be influenced by what comes before and after, so we have to think of it all as one big circuit.  Sometimes the solution is a buffer at the pedal's output.  You can try this experiment: connect a pedal that has buffered bypass to the output of your pedal and see if that changes the tone.

Can you provide a schematic?


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