Technology of the Superfuzz?

[surgesg]

Hey, I'm building a univox superfuzz as my first fx build. I've got it all breadboarded, and checked it over multiple times and it's not working. In doing some searching on this forum I caught reference to a "Technology of the superfuzz" article. Does this in-fact exist and could someone please point me towards it?

Thanks,

Greg

[panasonic_youth]

are you sure you arent thinking of 'technology of the fuzz face' at geofex.com?

[R.G.]

It exists - but it's on my hard drive, not my web page.

It needs some polishing and some navigation aids pretty badly before it's ready for public consumption.

Do you have a specific question or two?

[surgesg]

thanks for the replys. actually got it working tonight, the transistor leads were mislabeled and therefore reversed. gah! but hey, it sounds pretty rad.

anyway, the thing i'd most be interested in is what the specific stages do, what each transistor does? also, is there a way to increase the amount of octave?

thanks again,

Greg

[R.G.]

OK.

Q1 and Q2 - input preamp; Q1 is the gain, Q2 is an emitter follower buffer that lets Q1 have high gain; the clot of stuff from Q2's emitter to Q1's base biases Q1 and sets the feedback gain of the stage, along with some rolloff of highs.

50k pot is a drive control.

Q3 is a phase splitter to derive mirror image signals for the input to the octave stage.

Q4 and Q5 are the octave generator. They're connected collector to collector and emitter to emitter, driven out of phase by Q3. Whichever Q's base is driven high by Q3 is active, the other is turned off because the emitter is held (relatively) stable by that BFC across the joint emitter resistor. The active Q amplifies that half-signal to the jointed collectors. When the signal changes polarity, the other transistor takes over, so the output signal at the collectors is always negative going, and full wave rectified compared to the input signal. The 100Ks and 22ks to ground bias this stage. We'll come back to that.

The two diodes clip the full wave rectified output.

The clot of stuff around the tone switch is an attenuator in one switch position, and a mid-range scoop in the other. The scoop position gives you lots of boom and sssshhhhissshh/tinkle, what I call "instant hockey-rink" tone. The attenuator just lowers the flat signal level to match the scoop filter's output.

Volume pot is a volume pot.

Last transistor restores some volume back after the signal loss in the tone networks.

Remember the biasing networks? The 100K/22K on each side sets the base of the two octave generating transistors at matching voltages of (22/122)*9V = 1.63V, of which 0.5something is used in the base emitter junctions, and 1.0something is used in the emitter resistor. For proper operation, this setup needs the transistors to be identical and biased identically.

When did you last have a pair of identical discrete transistors? Unlike JFETs, they do exist, but the're not common. Beyond that, the biasing networks are usually 5% resistors. That bias voltage will vary more than 5% up/down on each side, so the bias on one transistor could be 5%+5% higher on one of the octave transistors than the other. In the worst case, this completely unbalances the octave stage, and you get little octave.

One of the seven (at last count) incarnations of the superfuzz has an answer to this: a trim pot on the transistor bias. My layout of the superfuzz, which I thought was available through General Guitar Gadgets, but which a quick check doesn't show there, includes this trim pot. It's a 10K pot, wiper to ground, and the ends of which connect to the lower ends of the two 22K bias resistors. This lets you balance the two halves of the full wave rectifier to get them producing as much octave as possible. In fact, I believe Mark Hammer put his trimpot on the front panel of his Superfuzz as an "octave" control.

More questions?

[B Tremblay]

Volume pot is a volume pot.

What?!?  That's just plain crazy talk!   :wink:

[surgesg]

rock. that should do it, all that's left now is to play around and get it to sound the way i'd like. thanks a lot for your help.


peace,

Greg

[RDV]

Should sound a bit like this.
SuperfuzzNotch
SuperfuzzNormArppegio
SuperfuzzNorm&OctaveSolo

RDV

[petemoore]

I found Q4 and Q5 very influential to octave sound [no surprize now..]
 I just reswapped them for most pronounced Octave.
 Now I'll splice in a 10k Linear pot at the bottoms of the 22k's to see if that gets me even 'closer' to max octave obtainable from the SF.

[RDV]

I don't think I want more octave. I lucked out I guess, as I didn't match anything.

RDV

[jmusser]

Man, you picked a pretty involved circuit for a first build. I think I could screw up building a booster! I'm glad to finally hear the sample of this. I wasn't sure if it would be worth the effort, but they'll be one in my future I'm sure. I believe I have a five gallon bucket of 2N2222 around somewhere. Did you guys use germanium diodes? Did you also use 2N2222 transistors throughout? I've listened to the Pushme Pullyou sample again, and I think that one is next on the agenda. Have any of you built Tim's Octup Blender? That's a very nice circuit, and it does very good blending of the original and octave signals, or does exclusively one or the other. I built the Gusses Simple Octave Up the other day, and that is one of the better octave fuzzes I've ever heard. Very heavy fuzz on that one. Thanks for the samples RDV.

[RDV]

Mines all 2N2222A except for the last one(vol rec) which is a MPSA18 for a bit more pepper. My diodes are Ge I got from Aron.

RDV

[Frances Rhodes]

hey y'all

i recently got into building myself a superfuzz and i found 2 slightly different schematics for it.
one starts with a 10µ cap followed by a 22k resistor
https://3.bp.blogspot.com/-cBIzyse_wes/T0EHt4QmTvI/AAAAAAAAA88/Y1fbps_nMsQ/s1600/univox_superfuzz_schematic.gif

the second one shows the opposite, first a 22k resistor followed by a 10µ cap.
http://4tubes.com/SCHEMATICS/Music-amps/Univox/Super%20Fuzz.gif

is one of them wrong, or the order of that resistor and capacitor don't really matter?

cheers

[thermionix]

the order of that resistor and capacitor don't really matter

[BetterOffShred]

While we're on the topic here, has anyone got any good mods for this circuit they would care to share?  I've been planning to build one for a while but I figure throw the mods on a toggle or something

[Aph]

While we're on the topic here, has anyone got any good mods for this circuit they would care to share?  I've been planning to build one for a while but I figure throw the mods on a toggle or something

https://aionelectronics.com/project/rift-univox-superfuzz-clone/

[BetterOffShred]

Interesting.  Yeah I was thinking of putting a pot between the diodes and ground to bring them in and out, and I guess reading that I should look into the tone variations.  Thanks for sharing

[Frances Rhodes]

you can also bring the trimmer out to dial the octave effect in or out.
and, also, i've been working on adding a tone knob, à la lastgasp art laboratories... but i haven't settled on component values yet for the non-scooped tone position

[digi2t]

This is my absolute favorite version.



2SC828R's work well too, but they have to be kept in the 150 to 175 gain range, with the octave pair matched as close as possible.

I lift the diodes to around 8 or 9K, just a tad to open up the roar a touch. This, and respecting the aforementioned gains, yields a wonderfully open sound for chords anywhere on the neck, and righteous octave leads.

For the tone section, I ended up using a 0.1uF cap.

[BetterOffShred]

Ah dope, thanks for sharing Dino! I will try this out