Build report: Mutantes Fuzz

[Uma Floresta]

For a while now I've been meaning to build this fuzz. This particular schematic was drawn by Doug Deeper of Mid-Fi electronics - he posted it in a thread a couple of years back, and I held onto it.

I finally got to it this weekend. I built it in an evening and got it working by the next evening. Very few parts, super simple and very 60's sounding. Apparently Doug was in a band called The Mules, and they used the Mutantes Fuzz on this song, which I've had on my iPod for a while. My build sounds just like the fuzz in the song.

http://thephoenix.com/BLOGS/onthedownload/archive/2006/03/27/Mp3-exclusive-The-Mules.aspx



You can get a fuller sound by increasing the size of the two 10uF caps. I have no pics or clips of my own, but The Mules clip really shows what it sounds like. It's a simple one-knob fuzz, not a lot of versatility stock, but it sounds great.

Other mods worth trying: Remove the second transistor and bridge the area where the collector and base were, and it's more like a distortion than a fuzz. Then remove the diodes, and it's a mild overdrive/dirty boost. Sagging the voltage doesn't really do much. In stock form, it sounds especially good in front of a dirty amp or overdrive pedal.

[Gus]

What is the power supply voltage?  9VDC 3VDC etc.

[Uma Floresta]

What is the power supply voltage?  9VDC 3VDC etc.

Standard 9vDC

[Gus]

I did not know there was a standard voltage.  9VDC is more common
 
  Some older effects worked at 3VDC.  IIRC a RM one has a voltage regulator to drop the voltage from 9 to a lower voltage for a section of the effect.  The black Ice has no power supply except the signal.

I posted the above for two reasons one working at lower voltage can change the max gain from a single stage and maybe DIY people might want to try lower voltages other DIYers have tried higher than 9VDC.

I am not a fan of that type of bias try different transistors and note the collector voltage also heat and cool the effect.  For something like that I like the BeeBaa distortion setup.

[Uma Floresta]

I did not know there was a standard voltage.  9VDC is more common
 

My standards are quite common. 

[Gus]

To be clear my posts were meant in a good way.
  What happen with the sound of that circuit or other circuits at different voltages? 

[Uma Floresta]

To be clear my posts were meant in a good way.
  What happen with the sound of that circuit or other circuits at different voltages? 

Yup, that's what I had assumed.

I tried it at 5v, 3.5v, and 1.5v. It got a bit murkier sounding, but didn't create any interesting effects or improve the sound, in my opinion.

[tiges_ tendres]

I have a copy of the original document that appeared in a Brazilian electronics magazine.  The article was written by Claudio Cesar Dias Baptista from Os Mutantes. It was translated by Munky, who I dont think posts over here any more.

Anyway, not all of the details were visible on the schematic, and there was also a page of mods suggested by Mr. Baptista.

The mods basically consist of a pot connected to the diodes, a limiter, as it is called in the documentation.  But there is also a Filter (Simple tone control that can be tacked on to the end of the circuit).

The other control is for attack.  On the schematic from the article there is a .1 uf Capactior that connects the Base of Q2 to a spot between 5k resistor on the collector of Q2 and the 10 uf output cap.  This is missing from the schematic listed in this thread.  Also, the mod for how to implement the attack feature isnt clear but it looks like some kind of pot and maybe a switch.

Marcos Munky's site is still up and you can find the .pdf there.

[svstee]

Drew up a vero layout. Not sure about it, especial the polarity of the electrolytic caps. Can anyone confirm?

[rousejeremy]

I think you need to move the trace cut after Q1's emmiter to the base, add a trace cut before the emmiter of the Q1 (between it and C2) and add a trace cut after the base of Q2.

[svstee]

I had my transistor flipped as well

Better I hope.
Thanks!

[svstee]

Can anyone verify the second layout?

[rousejeremy]

It looks right to me. You may want to make R3 a little more transparent so the trace cut underneath is a little more visible.

[SpencerPedals]

Link to the aforementioned info:

www.geocities.com/munkydiy/mutantesfuzz.pdf

[tiges_ tendres]

Link to the aforementioned info:

www.geocities.com/munkydiy/mutantesfuzz.pdf

Thanks Steve!

[bluesdevil]

Thanks for bringing this back up. Gonna put it on the breadboard tonight!!

[rnfr]

there is also an os mutantes octave fuzz that munky translated.  i've been meaning to give that one a try as well.

[biggy boy]

I was thinking about the above circuit and thought about the switch for the caps.
what about a SPDT ON OFF ON switch in this configuration?








Glen

[bluesdevil]

Got it breadboarded up. Used the PN2222's as per Doug's layout. Sound best with a .1uf input cap to my ears. Plenty of volume despite the germanium clippers. Decent fuzz, but nothing unique sounding as far as I can tell.... maybe I've already built too many and I'm a bit jaded. I'll try some higher gain tranny's next.

[bluesdevil]

Better retract here! Tried some little metal can 2n2484 transistors with gains around 300 hfe and got a more distinct sixties garage fuzz sound. Also a lot less noise than the PN2222's. I definitely recommend trying trannies around the 250-300 hfe range. Thanks!