Os Mutantes fuzz...

[LucifersTrip]

I was searching for some info on another fuzz and came across some info that burned me...
http://www.diystompboxes.com/smfforum/index.php?topic=34423.msg241392#msg241392

I've built the Os Mutantes fuzz in the past, but I never could get it to sound great. It always sounded boomy & muddy and nothing like what I expected. In the end, I wound up modding it to sound completely different than how it originally sounded.

Also, when doing research before building it, I read numerous other accounts of builders who were unsatisfied.

The problem is that the schematic floating around is heavily modded and totally different than the original.
Here's it is in Aron's gallery:
http://www.aronnelson.com/gallery/main.php/v/Schematics-etc/os+mutantes+fuzz.jpg.html

Here it is at Harmony Central:
http://acapella.harmony-central.com/showthread.php?1174781-rare-schematic-thread


Here are the differences:

1) input cap larger (.0047 instead of .003)
2) vol pot larger (100K instead of 15K)
3) 1.5K missing across vol pot
4) germanium diodes instead of silicon
5) different and much lower gain transistors (pn2222 ~100-200 instead of bc109c 400+)
6) .1 cap across B-C on Q2 missing
7) cap between Q1 and Q2 guessed at...unknown?

#1-5 will most likely make it much more boomy and muddy...burn!
#6 will tame it massively

I quickly breadboarded it, and as expected, completely different than what I had before...though, still not great.
I have no idea how you can make this thing spark with #6.

Anyway, here's the original:

[bluesdevil]

Mad Bean has it on his projects page as "Dead Pool", I think. Check it out, looks like he played around with the circuit and came up with some fixes to make it sound better, including recommended transistors and gains.
Can't recall the url offhand, but I know I wanted to give this one another shot real soon.

EDIT:
http://madbeanpedals.com/projects/Deadpool/docs/Deadpool.pdf

[LucifersTrip]

Mad Bean has it on his projects page as "Dead Pool", I think. Check it out, looks like he played around with the circuit and came up with some fixes to make it sound better, including recommended transistors and gains.
Can't recall the url offhand, but I know I wanted to give this one another shot real soon.

Madbean did keep the core of it, but also added/changed a good amount:
http://www.madbeanpedals.com/projects/Deadpool/docs/Deadpool.pdf

he kept differences noted above: #1, #2, #3, #5 (2N3565 hfe min 70 !?), but he actually left in #6 (but massively reduced it).
It might be cool, but I doubt he's getting close to the original tone either...

If you do try it, I'd love to read the results.


thanx for the reply

[bluesdevil]

I have a few of those 2n3565's on hand. A couple measure at 150-200 I'll try with it. Got a couple of things ahead of this, but I'll post back when I get to it.
About the original tone: It may very well sounded like shat anyway, but has got my curiosity as well.
Keep on Fuzzin'!!

[LucifersTrip]

I have a few of those 2n3565's on hand. A couple measure at 150-200 I'll try with it. Got a couple of things ahead of this, but I'll post back when I get to it.
About the original tone: It may very well sounded like shat anyway, but has got my curiosity as well.
Keep on Fuzzin'!!

sounds cool...but remember, according to the data sheet the original (bc109c) has hfe min 420
http://transistor-spravochnik.ru/description/bc109c/23582

hope it turns out evil!

[bluesdevil]

This made me want to get a jump on it so I cleared off my breadboard and jammed in a couple of 2n3565's (hfe 220 and 330) and was pleasantly surprised!! First off, the .1uf that's on the original schem (between collector/base of Q2) kills the sustain and without it is a noisy shrill fuzz..... the secret is replacing with the 470pf as noted on Mad Bean version. Without the .0047 input cap switch in it sounds like a Tonebender to my ears.... maybe a bit trashier and with a sputtery decay. Not that unique, honestly. BUT the real magic for me is with the .0047 (or .0033uf) input cap switched in. It sounds like nothing I've heard before... maybe similar to a Fuzz Rite on steroids. Really cool trashed out, nasally kazoo kinda thing. I like it!!
   Used the original silicon clippers, but went with a 100k volume pot. Tried a smaller output cap, that sounded okay, but the 10uf is fine and gives more character. I may put a trimmer on Q2's collector, though. Might smooth out the rough decay.
               Anyway, I'm glad this thread kicked me in the arse to revisit this obscure fuzz!!

[LucifersTrip]

This made me want to get a jump on it so I cleared off my breadboard and jammed in a couple of 2n3565's (hfe 220 and 330) and was pleasantly surprised!! First off, the .1uf that's on the original schem (between collector/base of Q2) kills the sustain and without it is a noisy shrill fuzz..... the secret is replacing with the 470pf as noted on Mad Bean version.

yes, exactly...I have no idea how you can get anything good with that .1uF. Usually a B-C cap is in the 50-200pf range, so even the 470pf seemed a little large.

Without the .0047 input cap switch in it sounds like a Tonebender to my ears.... maybe a bit trashier and with a sputtery decay. Not that unique, honestly. BUT the real magic for me is with the .0047 (or .0033uf) input cap switched in. It sounds like nothing I've heard before... maybe similar to a Fuzz Rite on steroids. Really cool trashed out, nasally kazoo kinda thing. I like it!!
   Used the original silicon clippers, but went with a 100k volume pot. Tried a smaller output cap, that sounded okay, but the 10uf is fine and gives more character. I may put a trimmer on Q2's collector, though. Might smooth out the rough decay.
               Anyway, I'm glad this thread kicked me in the arse to revisit this obscure fuzz!!

that sounds great!  what type of rough decay are you talking about?  you're easily getting unity, right?

...and if you have a chance, please measure the voltage of the 2 collectors at the point where you think it sounds good.

thanx for reporting...

[bluesdevil]

Jammed on it a bit more today and I'm coming around to liking the "Thick" setting too. I f you don't want to wait around to get some 2n3565's, breadboard board it up with those bc109c trannies and throw in that 470pf Q2 cap.
I'm getting over unity gain with the 100k pot, but you can reduce the value of the 22k resistor near output (remove) to get it plenty loud. I think the sputter at the very end of the notes decay could be a misbias... will try to rustle up a pot to tack on to Q2's collector and see what happens. I'm okay with it though, where I stand.... adds to the glitchiness. I think Madbean was pretty much on the money with the improvements. Original or not.

[Mark Hammer]

Is this the "Bat Macumba" fuzz?

[LucifersTrip]

Is this the "Bat Macumba" fuzz?

The schematic was titled "Distorter VII", so I doubt it would be used on their first album....that'd be "Distorter I"

If you ever find/confirm what they did use on the first, please post...

[GFR]

Is this the "Bat Macumba" fuzz?

I don't know, but "Bat Macumba" also features a sewing machine ring modulator. A broken volume pot attached to a sewing machine motor. The sewing machine pedal used to control the rotating speed.

I have scanned and shared the original article with this fuzz (from brazilian magazine "Nova Eletronica") once, I remember someone was translating it to english.

The original article suggests several mods, like a smaller input cap for less intermodulation, tone controls and a pot in series with the diodes.

[Solidhex]

  He mentions in the original text that each string on his brother's guitar had its own pickup which each had its own individual fuzz circuit. Pretty cool. I imagine the double voltage divider on the output might have been a product of having six fuzzes running in parallel? Been thinking of doing a ghetto version of that by distorting the bass and treble range of the guitars separately with their own Mutantes circuit.
I consider that .1 cap on across the base collector junction an error. Anyone who's tried the circuit I'm sure will see that a .1 cap renders the fuzz pretty useless. I'm guessing they meant .001. You can see that "." seems added later. Probably hastily.
  The circuit is pretty picky with transistors in my opinion. I think the 2N2222's are a good place to start. Too high a gain and the oscillation and noise gets out of control. It does help to tweak Q2's collector a bit depending on the transistor.
  There can be a lot of output once the volume pot value is brought up a little. I would just pick what sounds best. 1N4001's are good. I also liked usual asymmetrical two 1N914's with a single 1N914.
  There's various places to cut down on the hiss. Cap to ground on the input, cap across the transistors' collector/base junction, also the 22K can be increased to smooth things out. Depending on the transistors you'll need some if not all of those. 

[GFR]

There was an errata later.

It was republished later too as 0.001uF.

[GFR]

BTW it was called "R VIII" and not VII. The "R X" was also published.

[LucifersTrip]

There was an errata later.

It was republished later too as 0.001uF.

the B-C cap, of course?

BTW it was called "R VIII" and not VII. The "R X" was also published.

yes, one extra "I"

[GFR]

Of course. The cap between gain stages is 0.1u. Input is 10u with a switchable 0.003 in series, Output (to diodes 10u).

[LucifersTrip]

The cap between gain stages is 0.1u.

thanx...that was the missing value on the schematic

[charmonder]

Is there any more literature floating around the Internet about the vintage or current  os mutantes  electronic circuits?  As I understand they had most of their gear home built because of something like the Brazilian government  at the time didn't allow imported musical instruments ( is this true?)  in that case I'd like to see a bit more like amplifiers!


Oh yes,  and I had the chance to see the reunited mutantes live last year with Ariel pink!   Sergio seems to have at least one fuzz pedal inside the guitar, not sure if he still has the 6 parallel string fuzz thing, but it did sound mesmerizing and atypical on the chords, so maybe! And it seems likely that he has a delay pedal built into his the guitar, because he was controlling the self oscillation noises with a knob by the bridge pickup. I was very confused, i may be mistaken but it seemed that  with just the knobs on his guitar the was able to tweak many parameters like tremolo, filter delay and fuzz, even vocal effects.

[PRR]

> they had most of their gear home built because of something like the Brazilian government at the time didn't allow imported musical instruments ( is this true?)

No.... but like many places, Brazil could remain a land of forests and farmers with no profitable manufacturing industry or jobs. To grow local industry, many countries apply large import taxes on products which "could" be made in the country. Brazil's import tax on transformers is apparently equal to the price of the transformer: $10 for the transformer, $10 more to the tax-man.

Same thing for US amplifiers in Canada and England. You "could" import Fenders but the import tax was brutal. Some guy in England named Jim made some Fender Bassman clones for some guys named "Who", Gar Gillies made more original Garnet amplifiers in the Winnipeg scene. Avoiding import tax was part of Jim's and Gar's success.

BTW: Back in the 1960s Brazil really was mostly farmers getting ripped-off by global market brokers. Brazil's transformer industry is now very strong, stronger than the US transformer industry (which is all moved to China).

[Hatredman]

For completeness' sake, here is the original text from the Brazilian Nova Eletronica magazine, in portuguese (and without the later erratas):

http://gamal.com.br/rviii.pdf

Although is in portuguese, the pictures are clearer.