Design Challenge #1

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!
 
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!
 
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!
 
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.
 
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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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.
 
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.

Crazy Fuzz breadboard.jpg

Crazy Fuzz V2.3 sch.png

Crazy Fuzz V2.4 sch.png
 
Golly Gee Wally, that is pretty nifty! :ROFLMAO:

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

Crazy Fuzz V4.0 sch.png
 
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