Shaftsbury Duo Fuzz – A Hidden Treasure Revived.

Introduction & History

Back in the sixties Fuzz ruled the sonic landscape as far as guitars where concerned. Fuzz was first featured, in mainstream music in early recordings titles, by groups such as The Kinks and The Rolling Stones, these later in the decade evolved into the powerful riffs and solos concocted by Jimi Hendrix and his fuzz face.

This brings us to our review of the Shaftsbury Duo Fuzz, at the present day. This particular unit actually has quite a history. It used to belong to my father which together with my firemist gold Telecaster and a practice amp, was handed it down to me on my thirteenth birthday. This remember was in the late eighties, era of rock hair bands, pointy guitars and wild oversaturated distortion, so this pedal was soon relegated to storage when I bought my Boss HM-2.

I do however clearly remember using it to terrorize the school choir (I was the choir band lead guitarist at 12) when in my teens together with my 8 watt Badger practice amp!

Nowadays however most any piece of gear over 20-25 years of age seems to acquire a vintage status, so it seemed like a good time to unearth the Duo Fuzz.

The Duo Fuzz in reality is a re-badge Shin-ei FY-6 these were also badged as a Univox unit in the USA and under other brands in other countries.


The Repair Begins

As can be seen in the photos, an attempt in my teens to liven up my unit resulted in a pretty bad paint job. As far as I could remember, the unit had always worked so in theory should be easy to get going.

Well my assumption was wrong, upon opening the device I found several loose wires, a faulty battery snap, and all the connectors looked quite dull and rusty. Also a couple of the electronic components on the board seemed to have come loose.

The first step was to disassemble the unit, I cleaned up the input/sockets and re-soldered and replaced several wires which were intermittently faulty. (see Appendix A for solder tips)  

This however did not repair the unit. I then proceeded to research this unit on the internet, in the hope of finding some photos on the circuit and wiring. However, all the ones I did come across where of a different version of the circuit board that on my version of the pedal.

Then as luck would have it I stumbled on a posting on a forum, from the creator of a replica of my fuzz unit, the Wattson-FX company. This showed a photo of an original Shin-ei unit with a circuit board identical to mine. The photo helped tremendously and I also emailed a message to the manufacturer who happens to be a fuzz enthusiast and electronics expert.

He replied with specific instructions on the repair involving the input wiring which was incorrect. Many thanks to Jim "The Amp Surgeon" Sproul from Wattson Classic Electronics.

Wattson Super Fuzz Front
Wattson Super Rear
Original Duo Fuzz
Shin-ei Fuzz

We also hope to be reviewing the Wattson Fuzz units in the near future.

I plugged the unit in and … sound…..then a brief flicker of that chain saw fuzz came to life and fizzled out again.

Nearly there I thought.

I then checked all my wiring again for continuity and that was fine, but upon inspecting the circuit board I noticed two components where loose. One was a green polyester film capacitor that had simply come loose so I soldered that on, the second was an electrolytic capacitor that would fire up the circuit when touched. This component even upon re-soldering had the same problem, so it seemed the capacitor itself was faulty, possibly a loose connection on one of the legs.

I had a look through some old circuit boards and found a capacitor of the same specification on the circuit board from a discarded mouse. With this I replaced the intermittent component and finally let there be sound!


The fuzz unit sounds exactly how I remembered it, buzzy and chainsaw like further accented by my Telecasters ice-pick tone and single coil pickups. Tone 1 seems slightly scooped whilst with Tone 2 all hell breaks loose and your hands simply want to pick away the riffs to “Satisfaction” or “You Really Got Me”.

Have a listen to the mp3 examples below. These where recorded with a 1968 Telecaster and also for comparison with a Double Cut Les Paul with p-90 pickups.

1968 Telecaster Demo

P90 Les Paul Demo


An interesting and nostalgic project, the next step will be to either expose the original finish of the housing or repaint to original specifications. The Duo–Fuzz lives again!

By Ernest. H. Slade