Whats wrong with this Fuzz Circuit ?

[MartyMart]

http://aronnelson.com/gallery/Martys-layouts-and-photos/CONTROFZ

This looked like an interesting Fuzz/Dist+ type of layout, I've built it with
a TL072CP dual ic and get "Zero" output from it.
It looks good to me, here's how I'm wired up :

Input to pin 3 ( 1M to ground, 0.22 cap 100k from 9v&100k to ground )
grounded pin 4
270k across pins 1 & 2
100ohm/10uf from pin 2 to ground
Output pin 1 to the 10k/ .047 /diodes/ to gain potlug 3.
Pin 3 links to pin 5
Gainpot lug 2 returns to pin 6 via 100k and 0.33 cap
330k across 6&7
output to vol pot from pin 7 via 0.33 cap
power to pin 8

The "numbers" on the priginal dont make sense, so I'm wired up as a
normal "dual opamp" would be.
Can't make head nor tail of it !!

Any obvious "boobs" in that schem that I'm missing ??

Many thanks,
Marty.

[MartyMart]

OK solved it
I have "yet another" D.O.A brand new Alpha pot !!!! :x
When "squeezed" at the lugs it works .... !!!!

I'm getting my pots else where from now on ( was ESR ) ......

Marty.

BTW: Sounds good, just a bit too much "clean" signal through all the time
so I'd appreciate any thoughts on the pin 3 --> pin 5 link ??  Pot ?

[Ge_Whiz]

Hi Marty

I was going to say that the schematic worked okay for me, but the resulting sound is a bit weak. Nice idea, but...

Rumour has it that Gretsch invented it for its Country-and-Western customers who wanted something to zip up their predominantly 'clean' sound a bit. Well, the Controfuzz does have a mainly clean sound, with the fuzz coming through later - trouble is, C&W doesn't tend to be played with long sustained notes. I suspect it was one of the biggest pedal failures of all time - but might be worth a second look.

[MartyMart]

Yeah, its quite "weak" !
I cut the 3-->5 link and have almost no level ! I dont want to turn it into
a "Rat" - too many of those around
I'll have to re-think its use/ditch it ... could be a nice "clean" booster I
guess ..

Marty.

[Mark Hammer]

The Controfuzz is a very interesting idea which was overlooked.  Perhaps because of the gap between its properties and its intended market.

I've made one.  It works using conventional dual op-amps, and it has interestng possibilities.

Note that Gretsch originally configured it so that just about ANY signal would make the clipping stage clip.  This meant that the apparent sustain on the clipping channel would be much longer than the apparent sustain on the clean signal.  Of course, the builder has no obligation to have the gain set as high as it is ( [220k+100R]/100R = LOTS! ).  Turn the gain down by subbing a 2k2 resistor for 100R (and stick a 47p to 100p cap in the feedback loop), drop the 220k resistor in series with the 10k pot down to 22k or something like that, and you've got something like a Sparkle Drive, where the "duration" of each channel is approximately equal.

[MartyMart]

The Controfuzz is a very interesting idea which was overlooked.  Perhaps because of the gap between its properties and its intended market.

I've made one.  It works using conventional dual op-amps, and it has interestng possibilities.

Note that Gretsch originally configured it so that just about ANY signal would make the clipping stage clip.  This meant that the apparent sustain on the clipping channel would be much longer than the apparent sustain on the clean signal.  Of course, the builder has no obligation to have the gain set as high as it is ( [220k+100R]/100R = LOTS! ).  Turn the gain down by subbing a 2k2 resistor for 100R (and stick a 47p to 100p cap in the feedback loop), drop the 220k resistor in series with the 10k pot down to 22k or something like that, and you've got something like a Sparkle Drive, where the "duration" of each channel is approximately equal.

Fantastic Mark, Thanks a million as it now has a very "unique" sound:

Replaced 100r with a 2k7
Replaced 220k to gain pot with a 20k
Placed a 120pf cap across the feedback loop ( 1&2 )

I have a sound somewhat like a Univox "SuperFuzz" but without any octave.
At "zero" gain ( 99% clean ) its a nice clean booster
Points between are a much nicer gain/fuzz ontop of clean combo
FUll gain = Superfuzz tone  !!!   (within a few % it's bang on )
So can be used much better for chordal work, without the octave
Its just missing a touch of high end, so I may play with some caps here
and there ....

Excellent, Top marks to Mark
I also learned something here ..... AGAIN !

Marty.

[MartyMart]

MORE IMPROVEMENTS :

Make the input cap a 0.047
Make the cap before the diodes a 0.047
Change the two 0.47's at the back end to 0.22's

Losses the "Univox" tone a little, but us much less "Bass" heavy and has
some more "high end" clarity now.
Or make them switchable for some more "tones"

BTW : This is a "keeper" !!

Marty.

[Mark Hammer]

Well, if you are a Superfuzz fan, then consider replacing the 220k resistor before the fuzz pot with the traditional SF midscoop filter.  That ought to provide an attenuation similar to that achieved via the initially suggested fixed resistor change.

I'm not sure what the advantages of the cap replacements that you listed might be.  I'm not denying the possibility they deliver a more pleasing tone to YOU, but without being able to determine the actual low-end rolloff in the stock version, it is hard to know what possible effect those cap changes might have.  Certainly cutting the cap value in half will raise the rolloff by an octave, but if the original rolloff was 16hz, then clearly doubling that frequency won't be all that audible to many.

Still, diligent work on your part, and if it gets you the tone you want, or a tone you found to be previously unknown to you and pleasing to your ear and amp, then rules be damned!!

[MartyMart]

I didn't do the "math" just found it a bit "bass heavy" in particular pre
drive, so I guess the input cap change is most important !!
Definate tone change though, still has the "superfuzz" flavour ..

Marty.

[RLBJR65]

Marty, you must have it real bad! Just how many pedals have you built in the last month or 2?  

I re-drew the schem with the mods you and Mark suggested. (at least I think it's right)
http://aronnelson.com/gallery/Richard-Boop-RLBJR65/CONTROFZ_MOD

Rules be damned! Thats how I do things too, but thats mostly due to the fact that I don't no many yet.

[Geoff Hunter]

Finally got round to trying the mods....

I just changed the 100 ohm at the inverting input to 2k2, and the 220k before the fuzz pot to 22k as suggested.

WOW what a difference!  A strong and clear fuzz! cleans up well with the volume knob but a bit thin with the volume turned down too much, but still very nice sound.

Think i'll leave the fuzz level to max and take out the pot.  I like one knob pedals.

Thanks to Mark Hammer and MartyMart  for turning a rather dissapointing build into something very interesting!

[MartyMart]

Marty, you must have it real bad! Just how many pedals have you built in the last month or 2?  

I re-drew the schem with the mods you and Mark suggested. (at least I think it's right)
http://aronnelson.com/gallery/Richard-Boop-RLBJR65/CONTROFZ_MOD

Rules be damned! Thats how I do things too, but thats mostly due to the fact that I don't no many yet.

.... ahem, about 20 !! ( ':oops:' )
Thanks for the re-draw with all the mods, looks correct to me  
Nice to see someone else's build "rescued" - its a nice circuit now !

Marty.