This is a very unusual one - the Earth Sound Research Graphic Fuzz. Why is it so unusual - have a look at the schematic. It has no input or output caps, and the IC runs at +/- 4.5V. Practically half the parts on the board are for the split rail power supply.
Be careful with grounding connections as it's kind of unusual (see schematic), and it will behave weirdly on some settings, with oscillation etc., which is normal for this one.
Please note that this is a different circuit compared to the one on Guitar Effects Layouts - see the comparison down the bottom of this post. The one on Guitar FX layouts is based on a work-a-like, from what I gather, that someone posted in a forum to try and 'normalise' the design.
EARTH SOUND RESEARCH GRAPHIC FUZZ - VERO LAYOUT
SCHEMATIC
The schematic can be found in this thread on DIY Stompboxes. Look for the post from Goodrat, who was a former employee. Last post in March 2021 updated the schematic - nothing major, just added a 10k resistor at the output going to the volume control.
LTSPICE
There's little happening here - split rail power supply, opamp distortion, and some minimal filtering.
Comparing 50k to 1meg for the fuzz control (called filter on the pedal) - practically the same, leaving 950k of rotation on the pot wasted
This is from 1k to 50k - most of the action seems to happen in this range
I also tried the modded version on Guitar FX Layouts, and the traces look different - still a massive fuzz by the look of it, but even less range in the fuzz control.
This version is a far more regular-looking circuit, with coupling caps and a normal bias voltage.
