Modular Fuzz?

[bigjonny]

Hi all --

I am wondering if I can seek your input on a circuit design?  It is a variation on the Hornet, I suppose...

I have been looking at many modifications (mods) on the Fuzz Face (FF) circuit, in particular the mods (Fuller mods, Mayer mods) on GEO's "Technology of the Fuzz Face"  article, as well as Aron Nelson's "Hornet".  Everything seems to be the same basic circuit, with minor variations in resistor and capacitor values...

This got me to thinking... Why not build a modular FF of sorts?  Aron has already done this (mostly) with the Hornet.  66% of his resistors are trim pots.  So, why not take this thinking a few steps further?  Most the ideas are floating around on the Internet.  I'd like to "bring it all together" in one document with a few goals in mind:

Circuit should have many (useful) controls for ultimate tonal flexibility (I say 6 ought to do it: Drive, Volume, Bias, Contour, Bass, Treble & explained below)

Circuit should use PNP transistors, since many more good quality Germanium PNP transistors exist ("Fuzz calibrated" PNP sets are easily obtained from

Small Bear, too!)

Circuit should work w/ "industry standard" negative ground, as described at AMZ

Document should include parts list, circuit schematic and wiring layout (for perfboard), including true bypass w/ a 3PDT switch

Circuit board is a 16x16 perfboard pad, so we can fit 6 pots, a DC jack, LED, input/output 1/4" jacks, 3PDT switch, a battery, and the actual perfboard into a Hammond BB enclosure (I hope!).  Document should DEFINITELY show how to lay out all the parts on such a small area.
[/list:u]

ON TO THE MODS:

Aron has omitted the ~8.2k resistor off the collector of Q2 in his FF design (the Hornet).  Add a trim in there, a couple transistor sockets (as many suggest), and you can "tune" from classic FF to the more aggressive Hornet fairly easily.  One easy design -- lotsa tonal options

Why stop there?  Take Mike Fuller's mods, as documented at GEO:  slap in a controllable "Bias" pot before letting the signal into the circuit, and a  1k controllable "Contour" pot.

Two more controllable (knobs on the outside) mods -- bass and treble...

BASS:
Many say the input capacitor is "critical" to obtain the fuzz you like.  Why bother swapping caps until you find what you like?  That can change with venue.  Substitute a low value cap (~.0047uF) for the ultimate whiny input, and add a series 33uF cap + 100kA pot in parallel with the input cap.  You can then tune in your desired bass.  Disclaimer: I thought of this idea myself, but later found the same mod at Fuzz Central.  They had already figured out the component values, so I lifted the values from that circuit.

TREBLE:
GEO suggests a ~100pF cap across the base and collector of Q2 in FF circuit can "tame" the high end.  Sounds like a good idea to me, especially if Q2 is silicon, but in the interest of modularity, why not put the cap in series w/ a 500kA pot?  All the way clockwise would put 500kOhms resistance between the capacitor’s ability to connect Q2’s collector base.  Counterclockwise would introduce maximum treble cut.

I have collected most these ideas into a working PDF file.  Note that the red resitors (pots) are control knobs.  Any comments on the circuit would be most helpful!  For instance, I don’t have any 1M resistors to ground to drain the caps, to prevent "popping" when switching the effect on/off.  I am not sure where to put them.  Any more input is appreciated!

      -jOn-

[aron]

Good ideas. I did most of the mods you described in addition to sockets for nearly everything.

The variable input cap was (I believe) suggested by none other than Jack Orman and implement widely by NVN (Joe Gagan).

Wanna see incredible FF variation? please look at the NVN schematics.

All that being said, go for it!!!!

[Marcos - Munky]

Yeah, NVN effects are based in the Fuzz Face (at least some of their effects). They sounds cool and are very versatile. Now that you collected all this info, why not to try it by yourself and make your own variation?

[bigjonny]

Would love to peep the NVN schematics.  Forgive the ignorance, but do you have a handy link?

hope I made this clear before: this variation is based mainly on Aron's work (why mess with a good thing, right?) thowing in all the bits of "hot-rodding" I've seen around.  My desire is to have a DIY all-inclusive project document for perfboard, as one can obtain @ Tonepad/GeneralGuitarGadgets when purchasing PCBs.  That way, any ol' DIYer can come along and build a Fuzz any style they like w/ one design.

Any comments on the circuit I posted? http://users.sdsc.edu/~jon/fuzz.pdf

Where would I add the 1M resistor(s) to avoid "popping" when turning the thing on/off.  What about the value of what I have listed as C3?  I am not sure I understand what that does.

[petemoore]

I have quite a FF circtuits, 3 are in boxes.
 The open boards are for testing, and have alot of sockets trimpots, etc.
 Also something I like to do is start with a large resistor [say the 100k feedback resistor] and taper it's R value by adding parallel resistance to it. I just leave some extra lead on both ends of the body so I can slip one under for contact/testing or solder right to it.
 Juicing up the front end is something I like, like a Tonebender [Basically FF with an added transistor in front wired as buffer or booster].
 Gus's 3 transistor fuzz mods...etc.

[Marcos - Munky]

There are some schematics in this link:
http://www.diystompboxes.com/pedals/schematics.html
Search for Joe Gagan. The schematic of the fuzz looks fine. Did you tried it? And now you need to give a cool name to it.

[petemoore]

Tim Escebedo did alot of work with FF's..."Many Faces of Fuzz" page has a slew of modd FF schematics to it.
 I'm like always up for the 'new' FF sound.
 I like the Mosfet Q2 / 4401 Q1 combination in the Multi Face...EZ Face with Ge in Q2 is kool...basically there are seemingly endless permutations of that basic circuit.