Fuzzdriver Design Question

[Epameinondask]

Hello everybody.

So, I've been doing some research lately on how to design a fuzzdriver. I tried some circuits on the breadboard but none of them seem to work the way I imagined. What's the idea?

Being inspired by pedals like the Proco Rat, J.Rockett WTF fuzz, Mxr Super Badass Variac fuzz and Red Llama, I want to design a fuzzdriver (as I like to call it, I don't know if the term is legit  ), that will feature a knob that can make the pedal turn from overdrive/distortion all the way to heavy and thick fuzz.

From what I've found as I did my research, the MXR Variac Fuzz and the J.Rockett WTF are the ones that do what I have in mind best. Although the WTF Fuzz can do what I have in mind, you need to work out some setting to achieve od and different settings to achieve fuzz sounds, using both the gain and wtf knob (which essentially is a starve knob). MXR's Variac Fuzz is allegedly a Band of Gypsys fuzz with a tone and a "starve" knob. With no schematic being available, I didn't have the ability to experiment with it.

The Rat and Red Llama need to have a fairly high gain setting to turn from overdrive to fuzz.

So my question is: Can this be done with a single knob? Or is it too much to ask?

Thanks in advance 

[Quackzed]

ive had good luck in that regard with an "input cap blend" pot setup, if youve got a big fat unruly fuzz, lowering the input cap by degrees will start to tame the unulyness and fuzzness to the point where its much more 'controlled' distortion than fuzz... i'd imagine if you adjust the fuzz pot or gain pot lower it'd go fuzz---dist---overdrive though it probably wouldn't be the tube screamer mid hump type overdrive... as a test you could replace the input cap you have with say a .01 or a .001 and see where it gets ya. works surprisingly well for such a simple add on...

[antonis]

My fellow Theban general/statesman..

IMHO, you firstly have to decide if you want a "pure" clipping stage (just amp heavy overdrive) or a "mixed" one (diodes, LEDs, fets/bjts wired as diodes, etc)..

[Epameinondask]

Thanks a lot for your input guys.

The input cap blend is a method that I had in mind but haven't tried yet. I remember experimenting with input caps and indeed fuzz circuits sounded more like a distortion. If I remember correctly, there was a Devi Ever pedal with this kind of input cap blend. I read somewhere that the fatness control on the X series pedals of Roger Mayer, is an input cap blend. Will definitely give this a try.

The thing that really makes me wonder is how to select the clipping method. What I am really trying to say is that the way the circuit is clipping is what makes it sound like a fuzz or od/distortion and also the frequencies that are being amplified play a huge(?) role in the final sound/product.

My gut feeling (I'm not that experienced) says that a circuit without diode clipping is a more suitable candidate to try and experiment on. Am I wrong to make this assumption?

Please enlighten me 

[Quackzed]

id sya diode clipping can be fine, i'd say you just need a circuit with enough gain to go to fuzz territory, that means alot of gain and usually alot of bass into the circuit... beyond that most distortions will sound more like an od at lower gains... most od's tend to have a mid hump type tone where alot of distortions have a mid scooped or flat tone, but if you plan on an input cap blend type thing you're already rolling off bass so some kind of trble cut tone control would allow you to dial in a mid humped tone at lower gains with the treble and bass (inp cap bl) rolled down... rolling down the treble is a good idea for dist and fuzz (sometimes) as well, so you might opt for a dedicated treble roll off rather than a tone pot... really a fuzz face might be a good candidate for this, plenty of gain, a somewhat rounder less edgy clipping character and asymmetrical clipping as well (good in overdrives) fuzzy at full bass sidee of cap blend with reduced bass its dist and at full bass cut cap blend would be really overdrivey if you tailor the gain just so and roll off a bit of treble after itll do all 3 with one knob...

[Epameinondask]

Quackzed, thanks a lot.

Well, a candidate that I had in mind for this kind of experiment is the Roger Mayer Mongoose, which can on its own sound like a Fuzz-Distortion hybrid. After some experimentation, decreasing the gain resistor (100k) of the Lm308 can lead to some very very good distortion sounds and I'm very satisfied with the overall tone and character of the pedal. I think it's very unique and exciting. Increasing it, makes the fuzz sound even fatter.

But the thing I'm now trying to sort out is the "clarity" of the sound when on a distortion setting. At full gain, it sounds very good. But when I'm lowering the gain, it goes muddy. How can this be solved? Maybe playing around with the caps before and in between the gain stages could solve this.

Here's the schematic:
http://schems.com/bmampscom/effects_misc/RogerMayer_Mongoose.gif

[Quackzed]

well higher gain gets fizzy and too bright harsh without treble taming, the same tone setup will be too muddy dark at low gain, just the nature of the beast really , c4 c6 c9 are all cutting treble you could lower/remove those to get it (at high gain fuzz setting) bright as you can take then see if its still too dark at low gain... c6 100p c4 remove c9 remove (remove just one side so its easy to undo) these all tame remove treble, but removal might be too bright so you'll need to experiment... a resistor in series with a cap to ground will be like a shelving filter, bigger resistor less treble cut.... 22k is a good starting point if removing em is too much, try one at a time and see... c3 is cutting dwcwnt treble as well..

[Quackzed]