Build report: Mutantes Fuzz

[Uma Floresta]

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!

Interesting - I'll have to try those - thanks!

This is only the second fuzz pedal type I've tried, really. I've owned a couple of Big Muffs, but was never really into fuzz until now, so I'm not a connoisseur.

[Gus]

Look for the Bee Baa schematic (a link is in schematics one of the links at the top of the page)
Note the distortion section, note the biasing used and compare to the biasing used for the Mutantes Fuzz

One reason the Mutantes fuzz might change sound with different transistors is the bias used.  When you change transistors in the Mutantes note the temp and the collector and battery voltages, then if you write notes compare the sound with the different transistors.  You might also want to measure the hfe

Two cascaded transistor gain distortion stages like the Bee Baa and the Mutantes are fun to work with.

[bluesdevil]

Look for the Bee Baa schematic (a link is in schematics one of the links at the top of the page)
Note the distortion section, note the biasing used and compare to the biasing used for the Mutantes Fuzz

One reason the Mutantes fuzz might change sound with different transistors is the bias used.  When you change transistors in the Mutantes note the temp and the collector and battery voltages, then if you write notes compare the sound with the different transistors.  You might also want to measure the hfe

Two cascaded transistor gain distortion stages like the Bee Baa and the Mutantes are fun to work with.

Yeah, it would be smart to to start taking measurements for the different results you like. This one sounds totally different with the combinations I've tried. Kind of hard to pinpoint what I like the best.
    I actually got more fuzz with just 2 metal can 2n2222 trannies with both at only 100 hfe. Maybe my recommendation for a relatively high hfe for both Q's is not the best..... kind of blatty.
    A very nice, big sounding overdrive sound is achieved (in my case) with a metal can 2n2222 in Q1 and a 200 hfe 2N2192A in Q2. I'd like to have a switch to chose between 2 different Q2 trannies for this build!!
     

[tiges_ tendres]

Has anyone tried the BC109 in this?  That is what was apparently used in the original.

[GFR]

I tried BC109C's. It was really heavy and "messy", in a good way. Perfect for single line psychodelic stuff. With more than one note at a time, even with power chords, it was like the end of the world.

[tiges_ tendres]

I tried BC109C's. It was really heavy and "messy", in a good way. Perfect for single line psychodelic stuff. With more than one note at a time, even with power chords, it was like the end of the world.

Thanks for the report.

[Uma Floresta]

This design is even more flexible than I thought. Try this: remove second transistor (bridging collector and base sockets with a piece of wire), and replace  the first 10uF cap with a .047uF cap. I got the idea to do this from reading up on the Electra Distortion, and the many boutique variants on that theme (Greer Ghetto Stomp, Lovepedal Woodrow, Cot50, Super6, etc etc), and noticed how similar they were to this circuit. Basically they all consist of one silicon NPN transistor going into two diodes to ground.

Anyway, this mod makes into into a very nice sounding overdrive - better than the other attempts I did before. The key difference is reducing that first 10uF input cap so it's not so bassy - should have thought to do that. I'd say this does a very nice "tweed amp in a box" impression.

I'm going to wire this mod up to a 3PDT switch, to simultaneously bypass Q2 and reduce the value of that 10uF cap, and then add a toggle switch for two Ge diodes, no diodes, or two LEDs as diodes. Dirty boost, overdrive and fuzz, all in the same box. Oh yes.  Maybe I'll add a gain pot at the front of the circuit too.  

[GREEN FUZ]

I`m trying to knock up a layout for this fuzz and was wondering what is the deal with C5 on the original schematic. I can`t make out the value and it has been omitted from Doug`s schematic. After doing the obligatory search I found a thread where he explains his reasons for various value changes but nothing about C5. Any thoughts?

[Uma Floresta]

I`m trying to knock up a layout for this fuzz and was wondering what is the deal with C5 on the original schematic. I can`t make out the value and it has been omitted from Doug`s schematic. After doing the obligatory search I found a thread where he explains his reasons for various value changes but nothing about C5. Any thoughts?

I didn't even see that - looks like .1 uF to me

[GREEN FUZ]

Think you might be right. Marco`s translation describes an "ATTACK" mod whereby you replace C5 with a couple of resistors. Again I`m having difficulty making out the values. Probably a good case for bread-boarding.

[doug deeper]

if you put  .1 UF cap in there it kills the fuzz, id guess something around 500pf would be right, and that the coupling cap next to it is the .1uf.
the schematic i posted was just what i did to get it close to how i though it should sound.

[Uma Floresta]

if you put  .1 UF cap in there it kills the fuzz, id guess something around 500pf would be right, and that the coupling cap next to it is the .1uf.
the schematic i posted was just what i did to get it close to how i though it should sound.

Cool - I'll try adding that cap, see if it brings anything useful to the equation - also, check out my last post in the HM thread, just FYI.

[GREEN FUZ]

Cool - I'll try adding that cap, see if it brings anything useful to the equation ...

You might want to try adding the 1.5k resistor to ground also.

[Uma Floresta]

Cool - I'll try adding that cap, see if it brings anything useful to the equation ...

You might want to try adding the 1.5k resistor to ground also.

Good catch. I have the original transistors in the mail, as well, so I'll see what this sounds like originally designed.

I'm going to try a big muff style gain control after Q1 as well, see how that works out. It's really Q2 that is providing most of the fuzz, Q1 is mostly clean volume boost, so being able to simply reduce the volume from Q1 might be a more intelligent way to get it to sound like an overdrive than switching out Q2.

[Uma Floresta]

Okay, report on the two missing components. The extra cap (I used something like 500p) tames the nasal character a little on single notes. Makes it sound a bit more conventional, actually. The extra resistor just limits the maximum volume, but limits it too much in the 1 transistor overdrive mode, so I took it off. It does help tame things if you're not using any clipping diodes, so perhaps worth using it in that case. Maybe a larger resistor would work if you've got some kind of diode switching scheme, for more moderate volume limiting.

I tried a gain control after Q1 - the result was unsatisfying, as it sounded mushy with lower gain. I tried one at the circuit input and it sounded much better. Also, I tried some diodes parallel to the 500p cap between the collector and base, and that actually yielded a very Muff-like sound, especially with the diodes to ground switched out.

Now I think I'll just add a simple tone control, and call it good.

[Harry]

Alright so you guys got me interested in this now.

I'm trying to make out the mods section on the pdf:
Attack: looks like replace C5 for a 4.1k? resistor and a 100k log pot w/spst switch so the feedback is eliminated at minimum. I figure the last pot leg is disconnected.
Filter: looks like a tone control before the volume with two .003uF caps in parallel controlled with a 470k linear pot? I would think that a .006uF capacitor would be easier to find than a 470k pot.
Limiter: Can't make much of this out, but the AMZ saturation control would work here.
Does this sound right? Can anyone read it any better?

[tiges_ tendres]

Alright so you guys got me interested in this now.

I'm trying to make out the mods section on the pdf:
Attack: looks like replace C5 for a 4.1k? resistor and a 100k log pot w/spst switch so the feedback is eliminated at minimum. I figure the last pot leg is disconnected.
Filter: looks like a tone control before the volume with two .003uF caps in parallel controlled with a 470k linear pot? I would think that a .006uF capacitor would be easier to find than a 470k pot.
Limiter: Can't make much of this out, but the AMZ saturation control would work here.
Does this sound right? Can anyone read it any better?

I think that the limiter is just mixing how much of the signal is fed into the diodes.  I think the AMZ Saturation or Warp control would work as a mod here.

[GREEN FUZ]

Even squinting I can barely make out the values of the mods.

... 100k log pot...

Hang on, I can just make that one out .

[Harry]

Oh I was thinking ya'll could see it better my laptop has a monitor about 8". 

[puretube]

Oh I was thinking ya'll could see it better my laptop has a monitor about 8". 

EeePC?