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Someone on this forum suggested this might be a Fooltone '70 clone and as these sell for peanuts, i wanted to try one. Came in the mail today. Fooltone '70 - bullshit. It's a basic Si FF with rheostat in front of it. Sounds horrible. To call this abysmal would be a praise. Highly moddable, but still. Surely worth 20€ shipped, but still.

BOM (designations per original board):
Rx 100R (trace cut and added post design, most likely to cure possible oscillation)
R1 47K
R5 1M
R6 100K
R7 22K
R8 4K7
R9 4K7

C1 4µ7/50V
C3 220n/100V panasonic
C4 22µ/50V

D1 1N4001
Q2 2N3904
Q3 2N3904

Fuzz B2K
Tone B100K
Level A100K

Modded mine.

-Transistors to MP38A (hFE 78 and 91)
-R1 to 33K
-R7 to 10K (trimmed on breadboard to find good bias setting)
-R8 to 470R
-Shorted Rx
-Added 2k2 between fuzz pot pins 2&3
-C1 to 10n
-Cut trace between Tone pot's lug 1 and C1
-Shorted Tone Pot's lugs 2&3 with C1
-Added 2µ2 between Tone pot's lug 1 and C1

Basically swapped the transistors for a pair of nice old russian NPN germaniums, changed resistors per classic fuzz face values (setting the bias by ear) and tweaked the idiotic "Tone" pot to act as input cap blend. Pretty nice sounding pedal and quite usable now.

Hello, I purchased one of these the other day, and it sounded awlful! So, after checking this topic, I made some changes of my own:
https://cdn.discordapp.com/attachments/ ... 012332.jpg
https://cdn.discordapp.com/attachments/ ... nknown.png

Here's what it sounded before:
https://cdn.discordapp.com/attachments/ ... Before.mp3
and now after:
https://cdn.discordapp.com/attachments/ ... _After.mp3

I only forgot to put the 100pF capacitor between the Base and Collector of the first transistor in the schematic. It both cuts out the oscillation of the circuit at high gains, and smooths the treble a little. You might want to play with the value to reach the type of sound you're looking for, but I do recommend adding that capacitor for a more stable circuit!

After a little more fiddling, I ended up returning the 22k Collector resistor into place, and replacing the 4k7 resistor with a 560R one, which really make the circuit sound like a classic Fuzz. Everything is staying in place, but I'm arguing, with myself if I should change the blue LED with some other color.

blackcorvo wrote:After a little more fiddling, I ended up returning the 22k Collector resistor into place, and replacing the 4k7 resistor with a 560R one, which really make the circuit sound like a classic Fuzz. Everything is staying in place, but I'm arguing, with myself if I should change the blue LED with some other color.

Hey, thanks for posting those before & after clips. I got one of these on the way and always had a mod in mind, I'm going to start off with the changes you've made and go from there, will report back if I come across any interesting variations.

blackcorvo wrote:Hello, I purchased one of these the other day, and it sounded awlful! So, after checking this topic, I made some changes of my own:
https://cdn.discordapp.com/attachments/ ... 012332.jpg
https://cdn.discordapp.com/attachments/ ... nknown.png

Here's what it sounded before:
https://cdn.discordapp.com/attachments/ ... Before.mp3
and now after:
https://cdn.discordapp.com/attachments/ ... _After.mp3

I only forgot to put the 100pF capacitor between the Base and Collector of the first transistor in the schematic. It both cuts out the oscillation of the circuit at high gains, and smooths the treble a little. You might want to play with the value to reach the type of sound you're looking for, but I do recommend adding that capacitor for a more stable circuit!

Thanks for the schematic and mods. Bought a puffer to do my first mods on, so these will come in handy. One question though: What do the 100 uf and 10nf capacitors do?

I bought one of these and didn't bias up correctly, then I noticed the case says 9v-18v above the power jack, I made a quick adapter to hook up two batteries in series for 18v and it biases up correctly and sounds great that way. It works not only as a fuzz but as a pretty loud overdrive/boost. As you turn up the volume control it gets brighter as well. Cleans up well when the volume pot on the guitar is rolled down, I'll pull the transistors from mine and measure the hfe when I get an Atlas tester. The tone pot is there for humbuckers, and wah pedals, it's a common hack for that, similar to the "clean" trimmer inside the Analog Man fuzzes.

R5 is missing on the schematic. It's connected from the input of the tone pot to ground.

The transistors have around 230hfe in the 2 I bought now, they both seem to have issues with the circuit board too and the soldering on the input jack. I've had to fiddle with them both to get the noise down, bad connections.