DNA Analogic - Smoky Fuzz  [schematic]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
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asbestosaurus
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Post by asbestosaurus »

Cool pedal. Felt like more of a distortion than a fuzz, and a trace reveals why. That sense control is super interesting too.
The only component I couldn't positively identify was D1, generic looking silicon power diode with the only visible markings being "L7".
It's only doing sacrificial shunt reverse protection so it has no impact on the tone anyhow.
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mauman
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Post by mauman »

That sense control IS interesting, it looks like the pot is performing a double duty.

With D2/D3, it's an AMZ warp control, moderating the clipping to ground. CCW gives a normal waveform with no clipping at all, with clipping increasing as you go CW. It works with any type of diodes.

With R7/C7, it makes a lowpass filter. Fully CCW gives a 720 Hz corner that continues to roll off @ 6 dB per octave above that. Fully CW gives a 1.4 kHz corner that levels out and remains flat @ -3 dB above that. In between, the pot shifts both the cutoff frequency and the roll-off floor, @ 50% it's 520 Hz and the roll-off flattens out around -5 dB above that.

The 5 kHz pot value works well with both functions, and the two functions seem to be nicely independent.

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mirosol
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Post by mirosol »

asbestosaurus wrote: 31 Oct 2022, 02:21 Cool pedal. Felt like more of a distortion than a fuzz, and a trace reveals why. That sense control is super interesting too.
The only component I couldn't positively identify was D1, generic looking silicon power diode with the only visible markings being "L7".
It's only doing sacrificial shunt reverse protection so it has no impact on the tone anyhow.
Sense control is really cool. Nice to see there can be something interesting added to this style of a circuit.

However. I built one with this schem and i find my circuit to be pretty mild when compared to demos online. I was wondering if the R6 as 4K7 is in fact correct? Seems like quite low gain / high ohm value for a "fuzz" in this position. Didn't try it with 470R yet, but might do that next. Tried 470R for R6 and the circuit sounds pretty close to youtube demos i've found.
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asbestosaurus
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Post by asbestosaurus »

mirosol wrote: 22 Nov 2022, 11:02 Tried 470R for R6 and the circuit sounds pretty close to youtube demos i've found.
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You're right!
R6 is 470R, what a fool I am.
Updated schem attached.
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mirosol
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Post by mirosol »

...and a stripboard layout...
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