UNIVOX Super Fuzz vs SHIN-EI FY-6

I'll have to admit that I always thought these two guitar effects were the same circuit - well they’re almost identical; it's amazing what a difference two resistors can make.  That being said - they will sound almost the same on most settings, but there will be subtle differences primarily due to the lower boost level.

The Shin-Ei FY-6 has a 100k resistor instead of the 22k resistor found on the input of the Univox Super Fuzz, which really affects the output of the boost stage.

There's a slightly larger resistor on the emitters of the transistors responsible for the fuzz and the octave effect - 2k instead of 1k8, reducing the potential fuzz a little.

The Shin-Ei has a 1n cap across the collector and emitter of one of the transistors in the boost section, which is also common to earlier Super Fuzzes (grey box).  Later Super fuzzes had 2n caps (the colourful 1970's boxes).

BOOST

SHIN-EI FY-6

This is sweeping the Expander pot (fuzz) - on lower settings, there's much less clipping than the Super Fuzz.  Signal has been taken from the unfiltered output, as it's easier to see the differences.

UNIVOX SUPER FUZZ

Same as above, but more heavily clipped.

BOTH - NOTCH FILTERS

UNIVOX: Common Super Fuzz Mods

While cleaning up some old posts, I thought I might turn back on one of my old favourites - the Univox Super Fuzz.

Here are some common mods on LTspice.

STOCK SUPER FUZZ SCHEMATIC

TONE POT MOD

It's a nice simple one and the most common mod.  The tone switch is replaced with a pot to sweep between the notch and unfiltered outputs.  I think, in the process, this actually reduces the depth of the notch.

SUPERFUZZ NOTCH POT MOD

Another common mod - this time, the pot dials in the notch.  There is no unfiltered output, just varying degrees of the notch.

SUPER FUZZ DIODE POT MOD

This one can be a bit more subtle tonally, as it doesn't specifically effect the frequency response - the pot dials in a bit of extra resistance before the diodes hit ground.  Given the signal is already heavily clipped before it hits the diodes, this one is often referred to as changing the 'body' of the fuzz and is a little rougher around the edges.

Fuzz Machine: Unbranded Ibanez Standard Fuzz

The Fuzz Machine is clearly an unbranded Ibanez No 59 Standard Fuzz.

I occasionally buy a few parts from a retired guy with a shed full of vintage electronics and components, mostly valves and radio gear.  A while back, he mentioned that there were a couple of pedals buried somewhere in the shed.  

I was picking up some transistors from him today, and he'd managed to track the pedals down.  He was kind enough to let me have a look at it, to test before he sells - he wanted to make sure it worked first and wasn't happy with a bench test. 

FUZZ MACHINE  (AKA IBANEZ STANDARD FUZZ)

I took the opportunity to open it up and record voltages and scope results for future use, as I have been meaning to make the Ibanez Standard Fuzz for a while but have not got around to it yet.  

Apart from a few small cobwebs, it's spotless inside, the battery compartment is in good shape, and the faders feel fine for their age. 

And it sounds pretty much as expected...   it does what it says on the box.   Reassuringly, it sounds a lot like the Super Fuzzes that I've made.  Always good to get a side-by-side comparison - I only wish mine looked half as cool as this.  

WHAT DOES THE FUZZ MACHINE LOOK LIKE ON THE SCOPE ?

Signal:  Sine wave, 440hz, approx 130mv

Fuzz & volume on 100%

Battery 8.95v

Notch filter on

Notch filter off

First Stage, SK30 JFET

Drain        6.0v

Source     0.88v

Second Stage, C828 splitter, collector and emitter

Collector    5.0v

Base          4.0v

Emitter       3.5v

Third stage, C828, long tail pair collectors

Collector    4.0v

Base          1.1v

Emitter       0.5v

Last stage, C828

Collector    6.4v

Base          0.88v

Emitter       0.28v

Diodes

1N60 Germanium

Forward voltage 0.37v

UNIVOX: Super Fuzz, Notch Filter Mod

This is a handy little mod for the Univox Super Fuzz - especially for those who always leave the tone switch on the notch setting.  

Instead of a tone switch, there's a pot from the 100n capacitor to ground in the bridged-t notch filter, so the amount of notch can be dialled in.  If you really want to, you can have almost no notch...  but why???    

I usually like to include an octave pot in my builds, but I decided to keep the knob count down on this one.  Easy enough to add; there's space for this if you want to add it.

UNIVOX SUPER FUZZ - NOTCH FILTER MOD - VERO LAYOUT

UNIVOX SUPER FUZZ - ON THE BENCH

I used a few old transistors for low gain and a Motorola dual transistor for the long-tailed pair.  The diodes are Soviet-era D9B, not that it makes much difference on a Super Fuzz (they don't really do much).

I intentionally made a few resistors standing to leave room around the many 10uf capacitors and the sizeable dual transistor.  2 x 47uf capacitors have been used instead of the usual 100uf on the power filter, as the 100uf was too cramped.  

ZVEX: Octane 2

There's always room for one more Super Fuzz - this time, it's the Zvex Octane 2, which is a Super Fuzz with a simplified boost stage, and the notch filter can also be adjusted - probably more of a filter depth control than a tone control as such, but that's just what Zvex called it.

A Super Fuzz usually has a 2k2 resistor to ground from the emitters of the long-tailed pair instead of the 1k as listed on this layout.  If you have issues with biasing, try a 2k2 in this position.

As always, here's a larger-than-necessary vero layout.  

ZVEX OCTANE 2  - VERO LAYOUT

KAY: Fuzz Tone MODEL F-1

Commonly referred to as the poor man's Super Fuzz - the Kay Fuzz Tone Model F-1.   The Union Tube & Transistor Bumble Buzz is based on this (they're almost the same really).

Key differences are the lack of Fuzz control (the expander control), and it's missing a gain recovery stage at the end, so it's not going to be loud, so much so it doesn't even have a volume control.  The Bumble Buzz made up for this by using 4 x silicon diodes, instead of 2 x germanium.  

KAY MODEL F-1 FUZZ TONE - VERO LAYOUT

SCHEMATIC

ACE TONE: Fuzz Master FM-2

One more for the vintage Japanese Fuzz collection   The Ace Tone FM-2 Fuzz Master - a variation on the venerable Super Fuzz.

It's a little different as the "Expander" control is missing (bypassed), which is the same as running it full-tilt all the time.  It also uses silicon diodes instead of germanium and has a strange "Fuzz Adjustment" control, which is more of tone control.  Apart from a few little quirks, it's a member of the Super Fuzz family.

ACE TONE FM-2 FUZZ MASTER - VERO LAYOUT

UNIVOX: Super Fuzz

The Univox Super Fuzz is indeed super - possibly my most favourite octave fuzz ever...   that was until I discovered the Foxx Tone Machine.  It's now second on the list, although it's kind of special to me, largely due to Poison Ivy from the Cramps.

It's a legendary fuzz sold under many different names, with early beginnings in Japan as the Honey Psychedelic Machine.  

UNIVOX SUPER FUZZ - VERO LAYOUT

Note:  with the exception of the cap from Q4 & Q5 to ground, all 10u caps can be 1u without much effect on the frequency response.

Sixties version (grey box)

Seventies version with trimmer (super fuzz on stomp switch)

ORIGINAL UNIVOX SUPER FUZZ SCHEMATIC

There are two versions around - one is referred to as the sixties version, the other is the seventies.   

The sixties version has a 1n cap across the collector and base of Q2.  

The seventies version has a 2n cap in the same position mentioned above, and the 10k internal trimmer to adjust the octave

SUPER FUZZ LTSPICE ANALYSIS

Note:  all responses below use the first schematic, without the trimmer / 2n cap unless marked as such.

Reference voltages (approx, VCC ≈ 9.5V):

Use as a guide; results will vary.

Q1:   C 5.6V,   B 0.8V,   E 0.2V

Q2:   C 9.5V,   B 5.6V,   E 5.0V

Q3:   C 6.4V,   B 3.7V,   E 3.0V

Q4:   C 2.1V,   B 1.9V,   E 1.3V

Q5:   C 2.1V,   B 1.9V,   E 1.3V

Q6:   C 4.0V,   B 1.2V,   E 0.6V

Octave effect

The octave effect is probably clearer on the actual scope screen grabs at the end of the post, but here it is anyway.

Frequency response - pre-output stage

Output tone 1 and tone 2

Caps

Firstly, with the exception of the 10u cap on the emitter of Q4 & Q5, all 10u caps can be replaced with 1u caps with almost no impact on the frequency response.

As a reference, this is the output of the boost stage with a few different cap values.  At 40hz there's less than half a db difference between using 470n caps and 10u caps.  

1u is a safe bet, and you can easily avoid electrolytic caps with this value - why avoid electros?  Well at least try and avoid them on the input and output caps as electros leak, contributing to any potential switch pop.  The bigger the value, the higher the leakage.

If you do want to play with the frequency response, here are two caps that may not come to mind immediately.  The 10u from the emitter of Q4 and Q5 (C9) has a pretty large effect on the bass / low-end response.  The 1n cap on Q2 (C4) has a direct effect on high frequencies.

Trimmer

I'd never looked at the 10k trimmer properly until recently.  It's a common mod to adjust the amount of octave to account for using unmatched transistors for Q4 and Q5.   I'd built pedals using it, and could hear the differences, just never ran it on spice before.

As you can see, the trimmer affects the frequency response and output in certain positions.  No doubt a result of less octave being produced.

The trimmer does change the total resistance from the base of Q4 and Q5 from 22k to anywhere in the range of 22k - 32k depending on where you like to set it.

Alternatives to the stock trimmer set-up:

Reduce the 22k resistors to 18k - this way when the 10k trimmer is set to the middle position (5k), the total resistance is 23k, which is closer to the original value of 22k.

Another option is to only have the trimmer on the base of a single transistor, to adjust it to match the other.  Same values as above work just fine.   

SUPER FUZZ ON THE SCOPE - BENCH TEST

These are screen grabs from my oscilloscope. The input signal is a 440hz sine wave, approx 130mv RMS

This is the output of the first gain stage - which is just a boosted signal that has some clipping already.

The fuzz was sitting on around 50% for all below.  I didn't include the output of the long-tailed pair, as it just looks almost the same as the output without the notch filter (I may have even gotten these two images mixed up that are so similar).

This is a reasonably hot signal, I have other Super Fuzz builds where it's still a fairly clean sine wave at this stage.

This is the collector of Q3, which is where the signal is split and inverted from both the collector and emitter, which feeds into either side of the long-tailed pair.  

Now here's the emitter of Q3, which always seems a bit different to the collector

This is the output with the notch filter on

and again with the notch filter off - but who does that, right?

This is fuzz on zero, with the notch on - quite the strange looking wave