Hey Brian, (or anyone else), the engineer at my studio has asked me to build him a fuzz based on the one used by Os Mutantes way back in the day. There's a blurry scan of a schematic from a magazine article floating around out there, so I can build a stock one. There are also some mods in the article, but the text isn't clear enough to read, and it's not in English besides. There's an outfit from South America selling a version of this fuzz on eBay, but at $180, it's more than my buddy wanted to spend.
Does anyone have any more information on this fuzz, particularly the mods? (Brian, if this is in the wrong section, please move it to the correct one).
Do you have the scan available for posting? I'm curious.
Here's a link to the original article with a translation:
http://bestnetworx.com/uploader/files/48/mutantesfuzz.pdf (http://bestnetworx.com/uploader/files/48/mutantesfuzz.pdf)
There was some discussion at DIYstompboxes, but no one seemed to have precisely decoded the modifications. I couldn't find anything at FSB. TGP and TDPRI also had some discussions.
There's a simplified version on Aron Nelson's site too:
http://www.aronnelson.com/gallery/main.php/v/Schematics-etc/os+mutantes+fuzz.jpg.html?g2_imageViewsIndex=1 (http://www.aronnelson.com/gallery/main.php/v/Schematics-etc/os+mutantes+fuzz.jpg.html?g2_imageViewsIndex=1)
This one has some component changes so I'm not sure how true to the original it would sound.
Some suggestions were to place a pot under the second emitter as a gain control, or a pot in series with the diodes to vary the effect (I believe this is one of the documented mods). The "reissue" pedal has the "Attack" control, and I'd be interested in implementing this, but I can't make out from the document exactly how to do it. It seems it's varying the amount of feedback around the second stage with a pot, but I can't be sure. At this point, I'm leaning toward building it stock.
Yeah, I think you are pretty much right on with what the mods are doing. I'll see if I can re-draw this to make it more clear, with the mods.
Here's a first pass at a schem. I made a couple small alterations and some guesses. Don't know how well that "filter" control will work. Anyway, if anyone has the time or inclination to breadboard this and tell me what you think, we might be able to make something cool out of it. I'll try and do the same when time allows.
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Wow, thanks Brian, I can work from that! Your eyesight and interpretive skills trump mine by far. I've ordered and received a YY enclosure in fuzz blue from pedalenclosures.com and I suppose I'll just do a pad-per-hole type build. Time to place the small bear order....
Please post some pics of that enclosure! ;D They look cool, but seem a little pricey compared to the standard pedal parts painted enclosures.
They are a bit pricey, but for a one-off for my friend, I wanted something sort of unique. I'll post pics once I get moving on this project.