# Mutagen Fuzz…



## Coda (Mar 31, 2022)

This one showed up today, and was the only thing on hand that I could build without placing a parts order…or so I thought. A bit of background: I first discovered the Os Mutantes circuit last Summer sometime. Fast forward to a few weeks ago, and I was super excited to see the Basic Audio variant available here. I ordered it on Sunday (along with several other pcbs), and it arrived today. I wasn’t sure if I could built it, since there are no build docs, and was happy that, after looking over the PCB, it looked like I had all the parts I needed. 

Not many parts in this one. I placed the first component…I think it was a 4k7. Next component to place: 3M3. I grab my 3M3 drawer and pull out a component. I stopped…the bands didn’t look right. Popped it in my tester: they are 3k3, not 3M3. Ootz. Looking a bit closer, there were a few components I was short on. No BC549B (I do have C, however). I settled on 2n5088. Oh well. A few sockets later I was ready for substitutions. The 3M3 became two 1M5 resistors in series. 4n7 caps because 3n9s that measured almost 4n2. I socketed the diodes too cause hey, why not? 

I started this at 2pm this afternoon. At 4pm I plugged it in. It was a bit strange. Sounded kinda weird. I decided to replace the 5088’s with whatever else I had on hand that came close to BC549B. Settled on a trio of 2n2222 that all measured in the mid-200’s. 

This is a really cool circuit. It definitely is a vintage 1960’s feel, but with way more versatility than most 60’s fuzzes. You can dial in OD/Distortion tones, raw splatty fuzz, or buzzy goodness. I was pretty impressed, and I didn’t even really get to know it yet. 

Anywho, here’s a gutshot and a rough demo vid. No artwork yet because I’m working on that…


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## fig (Mar 31, 2022)

Tasty! Decided against the 3m3 on the last page?


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## Feral Feline (Mar 31, 2022)

I've already got an Os Mutantes type board, but still considering/wondering whether to get the PPCB version...


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## MobyOctopad (Apr 1, 2022)

Ooh, is that Fuzz Dog's Mutantes Fuzz, or is there _another _take on the Regulus VIII out there?


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## phi1 (Apr 1, 2022)

This build is pedalpcb mutagen, based on basic audio mutant fuzz. Probably similar but slightly different from what can be built with the mods on the Fuzzdog pcb.  I think clamp is the clipping diodes, saturation is probably blending in a larger input cap for more bass.  No build docs yet to see what’s going on exactly.


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## MobyOctopad (Apr 1, 2022)

Shit, sorry, should've replied directly to Feral Feline when asking about the other Mutantes board, but this is super helpful too!


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## Feral Feline (Apr 5, 2022)

MobyOctopad said:


> Shit, sorry, should've replied directly to Feral Feline when asking about the other Mutantes board, but this is super helpful too!


I've got the MadBean one,  maybe even have two of them, I can't remember — one for sure, "El Guapo", later renamed "LETFA".

Discontinued but you can still download the LETFA build doc and compare it to PPCB's, see if there's anything worth a mod.

Now back to Coda's regular scheduled Mutagen build report...


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## gila_crisis (Jun 2, 2022)

I've ordered the PCB, and looking forward to put this together, as already years ago I got interested into the Basic Audio original (David Torn was the pusher).
For transistors I'll try some BC183 and BC239, as I have a lot of these at home, which I used back then (with very pleasant results) in Big Muff clones.


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## gila_crisis (Jun 17, 2022)

Here it is my Mutagen fuzz!
Wonderful, super vintage and doom/sludge fuzz. Now I understand why David Torn likes this one a lot!

Report to my build: I used the transistors I had laying around in my workshop. 
I found this circuit to be very picky about transistor and hFe/gain, especially Q1/left and Q2/center: I first tried few BC183C, BC239C, BC550, or other high gain I usually use in BM and such, and I had a hard time making this circuit to work with these (with fuzz all the way up, I had no sound coming out of the pedal, like the transistor gain was too high and was choking the circuit). Then I found some old BC107A and BC107B and finally with those I got a wonderful sounding fuzz!
Q3/right on the other hand seams to be the easy spot: there also a MPSA18 was working very well. In then end there I put a BC109C.

It was a trial and error process, but I can't tell you the HFe of the transistor I used as I don't have a multimeter with a transistor socket.


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## andare (Jun 17, 2022)

The original has a switch for a small input cap. It's on my breadboarding list. I want to make a step by step tutorial for myself and publish it here. Can't find the time right now.


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