Archive for the ‘"Rab Fuzz"/ Kay Fuzztone Clone’ Category

Here is a Fuzztone F-1 clone (i.e. “Rab” Fuzz) I recently built and installed inside an Orange enclosure, as a tribute to the original Kay Fuzztone pedal. Personally, I think this looks better than black:




The original Kay was all orange (plastic), but I chose a black rubber foot pad here, because I figured an orange one would look start to look dirty rather quickly.

Here are some photos of the latest updated version of the “Rab Fuzz” (Kay Fuzztone Clone) Pedal:

DTS Rab Fuzz DTS Rab Fuzz

I’m very happy with this updated version…It uses military grade metal film resistors throughout the signal path, which help make it one of the quietest Kay fuzztones I’ve ever used.   Perhaps I will make an orange one next…

Some new circuit boards just arrived as part of an update/redesign of my “Rab Fuzz” which I’m excited about:

In this version I’ve moved the audio jacks off of the PCB. It requires a little more wiring, but this will allow the circuit board to interface with a wider variety of wah enclosures.  (Some older enclosures have sloping sides which don’t work well with the board-mounted Neutrik jacks.)

Here a Rab Fuzz pedal I built recently using a Vox wah case that came out rather nice (I thought):

Though the Vox wah gets props for having shiny chrome, the shell feels much heavier than a Crybaby case so I’d have the give the Dunlop the edge on it’s being more practical.

After installation of the conversion circuit board, it’s a Kay Fuzztone clone.   I’ve nicknamed it the “Trab Fuzz.”  🙂  Here’s what the finished pedal looks like – basically a stock Crybaby wah except for the blue LED and extra knob on the side.

It’s under the hood where things are clearly different from a stock wah:

Basing this project around a Dunlop Crybaby Wah enclosure, I designed a circuit board to be a direct drop-in replacement for the wah circuit board.  Unlike the wah, the Fuzztone needs true bypass, so I built the bypass onto the board using a relay, and this way the same switch from the old wah can be used.  All that’s required for assembly is to connect the circuit board as before and to disconnect two wires from the switch.  That’s it! Of course LEDs are not required, but are fun to add, too…

Here you can see the wah circuit board on the left, and the replacement board on the right.

(The two orange wires are part of a mod to the original circuit – they connect to a pot that acts as an extra tonal control over the fuzz distortion.)

Whenever I build I pedal I like to make a prototype version of the circuit on a breadboard.  This is a good way to test a schematic and to try different part values.  Here’s a quick look at the proto for the Rab/Kay Fuzz:

A note on the diodes:  I show 1N914 in the schematic. You can use these, but you will get a bit of a volume boost with the pedal.  That’s because these are silicon diodes and the originals were germanium diodes.  Silicon diodes clip at a higher voltage than germanium diodes.  If you want the circuit to be more like the original, then you can also use any of the germanium diodes out there commonly used in pedals.  I recommend trying a few to find what you like.

So getting together the parts for the Rab Fuzz pedal, or Kay Fuzztone clone we will need the following:

  1. Crybaby Wah, for the enclosure and potentiometer  (preferably with 100k pot still in good shape)
  2. Resistors, 1/4 Watt: 10k (x6), 100k (x5), 1.8k (x2), 22k (x2), 47k, 200k, plus one for LED (optional)
  3. Capacitors, Electrolytic (typical 16-50V rating is just fine): 1uF 50V (x2), 10uF 16V(x4)
  4. Capacitors, Film: 2200pF, 4700pF, 0.1uF (x2)
  5. Diodes:  Germanium (i.e. 1N34A), or Silicon (1N914 or other type of your preference) (x2), plus an LED (optional) NOTE: Schematic shows Si diodes but I really prefer and recommend Ge after testing many of these. Small Bear Electronics sells NOS Ge diodes which work great here.
  6. Transistors: 2N3904 (x2), 2N5088 (x2) or similar NPN
  7. Wire
  8. 3PDT Switch for true bypass with LED indication, or DPDT if LED not needed
  9. 1/4″ Jacks, at least one of which is stereo (nice for switching the power circuit)
  10. 2.1mm DC input jack, for powering the pedal with an adapter
  11. Circuit Board

Here’s something a little different from the other projects documented so far – a project designed for you to complete.  This thread will be devoted to building a “Rab Fuzz” or Kay Fuzztone clone from an old wah pedal enclosure.   The Rab Fuzz is used by  The Edge for the song “Elevation.”  You hear it mostly during the intro riff to that song.  It’s so named (designated as RABFUZ on Edge’s pedalboard) because as the story goes, one of U2’s technicians, “electronic wizard” Colm ‘Rab’ McCallister, took an old Kay Fuzztone pedal and rehoused the circuit in a sturdier enclosure for The Edge.  (Original Kay Fuzztones are made of rather flimsy orange plastic.)  The Kay Fuzztone was introduced to The Edge by Daniel Lanois during the recording sessions of All That You Can’t Leave Behind.  “Elevation” was the song U2 wrote around a riff played by The Edge using the effect.

This circuit replaces some hard-to-find components (transistors and diodes) with easier-to-find modern replacements, but the “Elevation” sound is all in there…

First, here’s a partial schematic of the circuit board (not yet showing complete wiring of the jacks and switch, etc.):



Changes to the original circuit include using 2N5088 transistors for Q1 and Q2 instead of 2SC644S, using 2N3904 transistors for Q3 and Q4 instead of 2SC828R, using 1N914 diodes for D1 and D2 instead of OA90, and changing the value of the potentiometer to 100k instead of 50k.

Edit:  I would like to add as and aside, that after testing several different diodes in this circuit, I personally think Germanium diodes are the way to go rather than the (Silicon) 1N914.  The 1N914s sounds good, but you get a bit of a volume boost since they clip at a higher threshold than the Ge diodes.  (This may or may not be to your liking.)