Friday, February 21, 2014

Fuzzway '67: Revisited

Well it has been a long time since I last revisited the Original 1966 Arbiter PNP Germanium based Fuzz Face. I posted here a while back about my experience with the Fulltone '69 using AC128 trannies which is an enhanced PNP version of the original:

It was a short post and I didn't really use this pedal a lot, mostly because it didn't sit well with my band and because our lead guitarist (although a Hendrix fanatic) could not cope with the over-the-top nature of the pedal. On top of that he plays humbuckers and that made things even worse.

Next I explored the Silicon path and got into building several versions before settling on a slightly revised version of the Fulltone '70. While with the Germanium PNP version I only had a bag of AC128 which I tested for hfe and leakage, tweaking the Silicon NPN with many trannies was a lot of fun and easier due to the vast amount of options at hand. 

If you wanna understand the differences in sound between the Silicon and the Germanium versions try to think about the differences in sound between the early Hendrix Experience era (Ge) and the Gilmour '70s sound (Si), although using different amps and different playing style. Other comparisons are the Hendrix sound of the Experience vs. Band of Gypsys, or Gilmour's sound of '68 vs. '73. It's the rough, bloomy, creamy and deep fuzz of the Germanium trannys vs. the sharper, smoother and edgier sound of the Silicon. Both classic, fantastic and work well with single coil pups, wah pedals and British style cabinets.

Lately I felt that I have neglected the PNP version Fuzz Face and after tinkering with it a bit I decided that it was time to revisit the circuit and see what else could be done to really get that elusive sound and to achieve this critical milestone on my fuzz quest.

So as you know or heard before, the fuzz effect was first accidentally obtained during recording a country song in 1960 by Marty Robbins. Check out this outstanding page for some cool country fuzz recordings including the legendary 1960 bass fuzz using a fried pre-amp channel: . In 1962 the first Maestro Fuzz Tone was sold to achieve all kinds of voicing effects for the guitar, but nobody really got the idea. Once the Rolling Stones released "Satisfaction", fuzz-mania hit the streets and everybody were buying fuzz pedals. Maestro Fuzz Tone (FZ-1, FZ-1A and FZ-1B), Mosrite Fuzzrite and Sam Ash Fuzz Box were the first commercial units on the west side of the atlantic while the Sola Sound (Gary Hurst) and Vox Tone Benders, The JHS Zonk Machine and the Baldwin Burns Buzzaround were the first to emerge on the British island. A year later, in 1966, Arbiter released the first Fuzz Face which was really a clone of the early 1966 Vox Tone Bender (MK1.5) and from all the units around, this was the simplest one. I think this was the first fuzz unit to use a double transistor feedback loop rather than multiple gain stages to achieve the saturated fuzz tone. The Fuzz Face's round shape was conceived by Arbiter while looking on the base of a microphone stand....ok....

Now, it's a simple circuit and because of that each element is critical. Every value makes a difference. 2 coupled transistors working in a voltage feedback biasing mode. Only 3 caps: in, out and the third on the feedback loop. 4 resistors: 2 for biasing the trannies, 1 for the feedback and 1 for the output and biasing together. The basic 2 pots controlling FUZZ and VOLUME are further enhanced by 2 more giving some extra functionality like BIAS which is a pre-gain control and a CONTOUR which controls the body of the output signal.
If you wanna read about the various Fuzz Face designs:
If you wanna read about the cicuitry of the Fuzz Face you should really check this link: 
More about the history of Fuzz pedals:
For the circuit I used and tweaked here's the best schematic out there:
A great verified and compact layout is given by mark and mirosol at:

My Psych '67 Fuzz Face clone
I played around with a lot of the values on this one and ended up using the basic Fulltone design as shown on the GGG website. I really enjoy the overwhelming possibilities given by the addition of the BIAS and CONTOUR controls. While the FUZZ pot sounds best at it's max, the true versatility of the sound comes from these extra controls. The BIAS is similar to rolling down your guitar volume which is the most elusive and sweetest spot of the Fuzz Face. It is what Hendrix sounds like when you think he's playing clean but it's so sparkly and biting that you know it ain't clean. The CONTOUR is like a tone or a body control which gives you more control over the spectral envelope of the sound. I like to keep it low so that the fuzz doesn't get too boomy.

What really got me going again with this pedal was changing trannies and re-biasing the 10k pot which had a huge impact on the sound. Low leakage trannies with Q1-70 hfe and Q2-110 hfe gave me the best results which in my opinion is a milder and smoother tone (far away as possible from a muff sound). The 10k pot was tweaked to get about 5.5V at Q2's collector-to-drain with the CONTOUR knob at halfway. 

Other options for tweaking were using a PNP 2N3906 Silicon tranny at Q1 which really gave me surprisingly good sound, lowering the VOLUME pot to 250k which sounded brighter, adding 33pF caps from collector to base on Q2 as suggested by R.G. Keen, and lowering the 100k feedback resistor to get milder effect. None of these options lasted on my build but they are good and are working. I would, however, add a STARVE pot for a dying battery emulation effect and a BRIGHT switch to change the input cap. Maybe later this year....  

Among the many myths around the Fuzz Face some are true, namely, single coil pickups do seem to work best with this circuit. Also, Marshalls, Vox and HiWatt amps sound better than Fenders as far as I can judge. I also found that the Fuzz Face stacks rather well with overdrive pedals behind it and, surprisingly, sounds even better and tighter when I used a treble booster in front of it, although driving it too hard will change the fuzz character. I always thought it was a no no thing, but, it really adds focus and crunch that the original pedal lacks. It made me think of the Keeley Fuzz Head which looks like a Fuzz Face with an added treble booster stage pumping it.

So that's that. Listen to it and build it if you still haven't. It's the real deal. The classic combination 
of Single coils-Fuzz Face-Marshall sounds even better when using a Marshall overdrive pedal like the Runoffgroove Thor. The cabinet emulation is a HiWatt 100W which is really the most transparent classic rock cabinet out there. I tried to cover all bases with the knobs at various positions and playing around with neck and bridge pickups and various volume levels on the guitar. You'll get the idea.

If you wanna turn your Fuzz Face '67 to an AnalogMan Sun Face just use the GGG Boutique '60s Fuzz Face schematic with the following 7 changes:
1. Replace 2u2 input cap with a 1uF one.
2. Replace the 100nF output cap with a 10nF one.
3. Replace 500kA VOLUME pot with a 250kA pot.
4. take the Q2 bias trimmer outside to an external knob for the Sun Dial. Use a 5k pot in series with a fixed 2k2 instead of the 1k fixed with the 10k trimmer.
5. You can leave the 50k input pot or use a trimmer internally like the one in the Sun Face.
6. You can leave the Contour pot or replace it with a fixed 470R instead of the 220R in series with the 1k pot.
7. Try to find the NKT275 germs instead of the AC128 which I normally use.

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