This Week on the Breadboard: The JHF-3 "Band of Gypsies" Fuzz
- Thread starter Chuck D. Bones
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Chuck D. Bones
Circuit Wizard
I thought about that too (the JFET, not the bird calls). I haven't tried it yet, but a JFET or MOSFET might work for Q3. We'd need to fiddle the biasing somehow. I ran some sims and the gain is lower with either FET compared to a BJT. Not surprising.
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steviejr92
Authorized Vendor
Would fiddling with R11, R12, and C11 be a good place to start for changing Q3 bias?
Sorry for the questions Im trying to challenge myself here lol
Sorry for the questions Im trying to challenge myself here lol
Chuck D. Bones
Circuit Wizard
Asking questions is a good thing.
I recommend you leave those three parts as-is. C11 has a strong influence on the freq response, gain and dynamics. 22uF appears to be the sweet spot.
R2, R3 & R4 set the bias for the entire circuit. If you make R2 bigger (or R3 smaller), then Q3-C goes up.
Q1, Q2 & Q3 are DC-coupled. That means their bias points are linked to each other. R5 & R9 form a negative feedback loop around all three transistors. That feedback loop stabilizes the bias point and also controls the AC gain. Q3-C is about 1.1V higher than Q1-B. You can't measure Q1-B directly because the meter will disturb the circuit. If you want to experiment with the bias, I suggest that you breadboard it as drawn and play it a while. Then trade R2 & R3 and listen to it again. The harmonic content and the note decay will be different.
Most of the components interact, in ways that it took me a while to figure out. You change anything and the results might surprise you. That was my experience anyway.
I recommend you leave those three parts as-is. C11 has a strong influence on the freq response, gain and dynamics. 22uF appears to be the sweet spot.
R2, R3 & R4 set the bias for the entire circuit. If you make R2 bigger (or R3 smaller), then Q3-C goes up.
Q1, Q2 & Q3 are DC-coupled. That means their bias points are linked to each other. R5 & R9 form a negative feedback loop around all three transistors. That feedback loop stabilizes the bias point and also controls the AC gain. Q3-C is about 1.1V higher than Q1-B. You can't measure Q1-B directly because the meter will disturb the circuit. If you want to experiment with the bias, I suggest that you breadboard it as drawn and play it a while. Then trade R2 & R3 and listen to it again. The harmonic content and the note decay will be different.
Most of the components interact, in ways that it took me a while to figure out. You change anything and the results might surprise you. That was my experience anyway.
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steviejr92
Authorized Vendor
Ill do just that, breadboard it and play with it then see what changing the bias does.
Seems like every component plays an important role and the circuit is sensitive to change. Sounds like a fun one to experiment with!
Seems like every component plays an important role and the circuit is sensitive to change. Sounds like a fun one to experiment with!
KR Sound
Well-known member
Looks like ON/OFF/ON
Chuck D. Bones
Circuit Wizard
Just make sure you only change one component at a time and make small steps, otherwise it's easy to get lost.
Chuck D. Bones
Circuit Wizard
I'm working on a higher gain version, just to see if it has any merit.
fig
Village Idiot
Checking to see if there is anything to gain by it eh?
Chuck D. Bones
Circuit Wizard
Enclosure can be found here:
3 Knob 'Fuzz Case' Enclosure - Drilled with Rubber Beard, Back Plate, Feet & Screws. - Fuzzcases
3 Knob 'Fuzz Case' pedal enclosure.Handmade in England by ‘Fuzz Cases’ in sand casted aluminium.Get your 'Treble & Bass' face on or add that external bias knob you've always dreamed about.First edition mid 60’s rounded nose, thick-walled style enclosure.The unit comes with the footswitch hole...
fuzzcases.com
RetiredUnit1
Well-known member
for 40 bucks more you can just get a fuzz face from sweetwater......
mybud
Well-known member
Indeed it does, and many thanks for this gem, @Chuck D. Bones.
I subbed a 558 for Q1 (not having any 560s at hand) and a 2N1304 for Q3. Lots of gain and girth (with 'fat' switch engaged) on tap. Lovely stuff.
Feral Feline
Well-known member
Great idea.
Rip out the guts, house them in a smaller enclosure and flip it on eBay/Reverb/Kajiji/Etc.
"Reduce wasted space on your pedalboard — REHOUSED FUZZ FACE for sale..."
Then you've got yourself a big round enclosure that... wait a minute...
RetiredUnit1
Well-known member
Yeah I just meant that $130 for an enclosure is far from a competitive price when you don't even have to source parts for $169.... Square is definitely a much more affordable form factor!!!!! Plus the whole round peg in a square hole on the pedalboard......
Feral Feline
Well-known member
Dude, I heerd yah the foist tahm! I was just being my usual mischievous frivolous clowning self.
or if you prefer
Never take my posts too seriously. However...
Honestly, seriously, I want to get one or two of the Mini Fuzz Faces plus a big one and do exactly what I described — transfer the guts and sell the rehoused circuits to recoup some of the dosh 'cause those big FF-enclonesures are expawnsseeff — and I don't think I could even find the Mini-FF enclosures in the DIY market — so I gotta buy and use the emptied FF enclosures for my own nefarious purposes. Seriously, I've been keeping an eye out especially for the Mini on the used-market but thems that haves them think they're made out of SoLiD gOLd...
"If space is a factor..."
...then the enclosure can be a LOT larger.
Larger than this pic. Something so large that James Webb would be proud.
Chuck D. Bones
Circuit Wizard
The solution is simple: get a round pedalboard.
Chuck D. Bones
Circuit Wizard
BTW, I'm calling the schematic in post #6 "final." I tried several different things but none of them sounded as good at that config.
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