What are the options for a tone shaping mod on a fuzz?

[kleydj13]

And what's your favorite?

Thus far I've breadboarded my fuzzes (mostly fuzz face clones) and swapped input and output caps to my ear.  Works great for that situation, but those boxes lack versatility and I have a few friends who would like me to build them a fuzz and want a tone control (they're used to OD's with plenty of tone shaping features).  So what tone shaping mods do you add to your fuzzes?  What works best? 

These are options I'm aware of:

Dropping a tone circuit into the fuzz circuit
Joe Gagan's blend control
switches that select different input caps

I've put switches in to select different input caps and have had some success.  I've not tried the other two options, and I'd appreciate any wisdom to adding some versatility to gnarly fuzz circuits.

[Mark Hammer]

The most useful tone-shaping control for just about any distortion-oriented pedal is one that will let you adjust how much treble content gets out, in a manner that will let you set your amp fro a nice crisp rhythm sound but not have to be punished for it when you turn the stompbox on.  In other words, a sort of treble-from-the-amp-compensation control.

That can take a few forms.  One is certainly a variable or fixed lowpass filter on the output.  Another way is to add more oomph to the bottom, perhaps on the input, such that you can lower the overall output level and the treble won't seem quite so bad.

Another mod that can work well in some contexts is panning between AC bypass caps of different values.  You will often see circuits where there is an electrolytic cap to ground from the emitter of a BJT transistor or the drain of a JFET.  Alternatively, that cap will be connected to the drain or emitter via a variable resistance.  The lower the resistance between cap, ground, and that emitter or drain, the greater the gain applied....within that portion of the spectrum dictated by the value of the cap.  You can kill two birds with one stone by tying the wiper of a pot to the relevant drain or emitter, and using it to pan between two different cap values (e.g., 22uf and 3.3uf), so that you get varying degrees of gain applied over the full spectrum or across the mids and highs only.

[Joe Hart]

Joe Gagan's blend control. Super simple to implement and super simple to use (unlike some tone controls that get too "interactive" -- I don't like that!). I use higher and lower values than he used, so I can get some extreme control from heavy bass to slicing highs. I love it.
-Joe Hart

[edvard]

Because of the highly subjective nature of "tone" regarding fuzz effects, I'm wondering if it would be more effective (see what I did there?) to simply run the output to an EQ pedal before the amp, which would go a long way towards re-tailoring the fuzz sound back to something resembling the straight tone so switching isn't so dramatic.
Every pedal is going to add it's own "flavor" to the tone, and the biggest complaint I have heard is folks dialing in a nice fat straight amp sound and then they kick on the fuzz and the bass either disappears or overwhelms.

Hmmm... based on that observation, perhaps a Bass cut/boost or shelving control would be most appropriate...

[Processaurus]

I strapped Mark's "Stupidly Wonderful Tone Control" on a fuzz factory clone, and it was wonderful as far as making it have a usable tone with different amps.  Originally it had a Big Muff type Hi pass/Lo pass panning tone control, which didn't cut it.

Marks (and the Rat's which was the inspiration behind it) works by sliding a gentle single pole lo pass filter up and down the frequency range. 

One of my favorite tone shaping controls is the Korg MS20's resonant filter (and other generic synth Lo-pass filters), because it is a similar type operation, but has resonance at the frequency where it starts cutting off, so YOU decide where the treble is, and how much.

[smallbearelec]

I used a tweaked DS-1 tone stack in my Fur Face:

http://www.smallbearelec.com/Projects/FurFace/FurFace.htm

and like it very much.

[Dragonfly]

Try the Shin-Ei FY-2 tone control section (or Marks modded version of it) - works well with many fuzzes.

Another option is to use a switch to go between two (or more) DIFFERENT tone controls. That way the user can choose what works best for their rig.

Oh - and some tone controls (like a BMP) may need an additional gain make up stage, as they can suck some volume from the overall output of the circuit, depending on the setting.

[Mark Hammer]

Again, tone controls for distortions move along two paths: EQ and re-voicing.  One is for getting the sound acceptable and not too jarring, given how the amp is set.  And the other is for getting different "characters" out of the pedal.  The BMP-style hi-lo panpot is more of a re-voicing type, and the SWTC is more of an EQ type.

[fuzzo]

Why not a parametric EQ on mids and bass/treble like a schematic from Anderton ? I'm thinking about that but it makes a lot of knobs for a fuzz  and i'm not really sure it will stay "musical" with that kind of tone control

[kleydj13]

Thanks for the clarification Mark.  I definitely think I'm shooting for more of a EQ than a re-voicing.  I think I may be leaning towards trying Gagan's blend knob as I don't have a tone of output to spare. 

One thing that I am a little puzzled about: I've toyed with boatloads of values of input caps - from .001 to 10 uf.  The larger the value the more bassy the tone.  Lower values, like .022, produced a very biting tone with plenty of treble and the bass seems to be cleaned up quite a bit.  There definitely is some EQing going on. 

On the other hand many of the tone circuits I've been looking at (many in the schematics section of this forum) for pedals are inserted near the end of the circuit. 

What are the characteristics of the two different tone shaping sections?  i.e. how would Gagan's blend or a switch that selects different input caps differ in tone shaping ability than the stupidly wonderful tone control or even a full BMT amp style tone circuit?

[Mark Hammer]

The first rule of distortions is that they always give you harmonics of what you feed them, in proportion to the amplitude of any given spectral portion of the input. 

The second rule is that guitar signals are not uniform and most of the spectral energy usually lives in the basement or ground floor, with much less living upstairs.  So, if you trim the bass from the input signal, it pushes the circuit less and you shift the harmonics created from primarily harmonics of lower fundamentals that might obscure the middle-range notes, to proportionately more harmonics from the middle and upper-range notes.  Trimming the bass to achieve harmonic balance is precisely what the Tube Screamer does, and is the principal strategy underlying that design.

So, trimming the bass at the input will alter what harmonics are produced, and how easily, whereas post-clip tone-controls alter the relative balance of harmonics that have already been added by clipping.  Occasionally the two can mimic each other to a limited degree, but generally they tend to produce different effects.  If you look closely at a number of the distortions that DOD has produced over theyears, you'll see that many of them employ resonant boosting ahead of the clipping, to determine the overall character of the distortionproduced, and tone-shaping after for more custom-tailoring.

[tubelectron]

Hi,

If you want a "psychedelic mid scoop", you can try the T-filter used in the Companion FY-2 Fuzz or even in the Univox Superfuzz, but you will probably need a recovery gain stage after the filter - I tried the T-filter of the FY-2 and it works well...

A+!

[Dragonfly]

Again, tone controls for distortions move along two paths: EQ and re-voicing.  One is for getting the sound acceptable and not too jarring, given how the amp is set.  And the other is for getting different "characters" out of the pedal.  The BMP-style hi-lo panpot is more of a re-voicing type, and the SWTC is more of an EQ type.

Definitely agreed. To me, "EQ" is quite a bit different than "shaping or voicing".

To me, when the OP first says " want more versatility", that means the ability to "shape" the overall sound, which would indicate a stack like the BMP, FY-2, etc ...rather than a normal tone stack.

( In fact, with things like FF circuits (that the OP has mostly played with), simply using a pot to bias the collector of Q2 goes a long way in shaping the overall tonality of the circuit. )

So, when the OP learns the difference and later says "more of an EQ", I think he would be well served by the SWTC, or the 1 knob Marshall tone control, the Gagan blend, or a similar tone stack.

I think that's what causes a lot of confusion and frustration - people having different "definitions" of what something should be. It's definitely not the OP's fault at all .... it's just good that you (Mark) took the time to explain the difference between voicing and EQ'ing, so that the OP gets the best possible solution.

Kudos.

[Mark Hammer]

Hi,

If you want a "psychedelic mid scoop", you can try the T-filter used in the Companion FY-2 Fuzz or even in the Univox Superfuzz, but you will probably need a recovery gain stage after the filter - I tried the T-filter of the FY-2 and it works well...

A+!

Go to the madbean site and see what Z-vex used for the Octane III pedal.  It is a variant of the variable mid-scoop but with a gain recovery stage to compensate for the passive loss.  Works great.

[jrod]

Hey, Check out this fuzz circuit from a magazine article posted on the AMZ blog. It has a SWTC type circuit that can be added (Fig.4.). Thought this may be of interested to you.