[cbg1]

found this one in the pedal box
original builder left the leads short so it was hard to get good pics
only info i have found so far is for a model 826 EKI 826 Fuzz Box - www.davidmorrin.com

this one seems to have the control reversed
no apparent boost in signal when engaged, fairly dark with a touch of fuzz going to brighter with a moderate amount of fuzz.
the owner of the site mentions 2TEF having the input and output signals being in phase as well lists some fuzzs based on this topology.

not sure if this one should be left as is or if it could be used as a start for modification.

any info would be appreciated

cheers

 

[Paul Running]

What's the number on the transistors?

 

[cbg1]

was surprised to snap this one...lol

 

[mhammer]

It's a buggered-up silicon Fuzz Face topology.

Interestingly, if one raises the resistance of the path between the emitter of Q2 and base of Q1, you start to move towards "zippery", then "velcro", and finally glitchy. I first came into contact with it in the ZVex Woolly Mammoth "Pinch" control, and experimented with it in other circuits, like the Jen fuzz and EHX Double Muff.

The 680k collector resistor on Q1 is wayyyyy higher than what one usually finds on silicon FFs, but then I don't know what transistors are used, and to be honest don't understand much about biasing.

That said the wiring of the pot is VERY unusual and it looks like there are errors. A "normal" FF would have the 1uf collector cap on Q2 going to a volume pot, or in this instance the 68k/10k pair as a fixed volume level divider. There would also be NO connection whatsoever from the 50k emitter pot to the output. What's shown as 1nf and 1uf would be the opposite values and the 1uf cap from the pot wiper would go to ground.

That would make it conform to a FF topology. But there are so many differences between this circuit and a "normal" silicon FF derivative, that it may be intended to sound and work differently, and efforts to bludgeon it into being a FF misguided. I guess we'd need sound samples to know.

 

[cbg1]

It's a buggered-up silicon Fuzz Face topology.

Interestingly, if one raises the resistance of the path between the emitter of Q2 and base of Q1, you start to move towards "zippery", then "velcro", and finally glitchy. I first came into contact with it in the ZVex Woolly Mammoth "Pinch" control, and experimented with it in other circuits, like the Jen fuzz and EHX Double Muff.

The 680k collector resistor on Q1 is wayyyyy higher than what one usually finds on silicon FFs, but then I don't know what transistors are used, and to be honest don't understand much about biasing.

That said the wiring of the pot is VERY unusual and it looks like there are errors. A "normal" FF would have the 1uf collector cap on Q2 going to a volume pot, or in this instance the 68k/10k pair as a fixed volume level divider. There would also be NO connection whatsoever from the 50k emitter pot to the output. What's shown as 1nf and 1uf would be the opposite values and the 1uf cap from the pot wiper would go to ground.

That would make it conform to a FF topology. But there are so many differences between this circuit and a "normal" silicon FF derivative, that it may be intended to sound and work differently, and efforts to bludgeon it into being a FF misguided. I guess we'd need sound samples to know.

not sure if you are referring to the website drawing model 826 or the circuit board photo.model 726...or perhaps they are the same circuit
the transistors being used are 2N 3904

 

[Paul Running]

2N 3904

A very common transistor...the workhorse of the industry.

 

[mhammer]

Morrin seems to be keenly aware of what a true FF circuit looks like, and has multiple drawing showing them. I looked for a 726 drawing but could not find one. Perhaps the 826 circuit he shows was originally misdrawn/mistraced, and he simply reposted it unquestioningly. It happens.

There are, in fact, plenty of silicon FFs using "garden variety" transistors, like the 2N3904. Will they "sound like" a classic Arbiter germanium unit? Likely not. Will they produce a musically useful fuzz tone? Certainly...once biased right.

As an aside, some time in the mid-'90s, Mike Fuller posted that the "ideal" germanium Fuzz Face used a transistor with an hfe of around 80-85 for Q1, and around 120 for Q2. The vast majority of 2N3904s will exceed that considerably, but then so will most silicon transistors. Which is why I point to biasing.

 

[cbg1]

Thanks for the replies and the information.

 

[mhammer]

Well, it seems the 826 circuit has a pedigree. I was looking in my hard drive for something entirely different and found this. It's a tiny bit different in the component values, but 95% the same.