Fuzz Makers' Roundtable

September 20, 2011

MORE THAN ANY OTHER DISTORTION EFFECT, fuzz pedals have been subjected to a seemingly unwarranted amount of microanalysis, especially for such a simple circuit. Consider just the subject of transistors, which many players consider to be a non-subject except when it comes to effects, and particularly fuzz. The sonic wonders of germanium and silicon transistors are routinely debated by guitarists who wouldn’t be caught dead plugging into in a solid-state amp, and fuzz pedals often take on mythical proportions as generators of tone when discussing the virtues of vintage units such as the Fuzz Face, Big Muff Pi, and Tone Bender.

In your opinion, what is the most iconic vintage fuzz pedal?

Michael Fuller: I choose the Fuzz Face, but not for the obvious reasons. A few people—Jimi, Duane Allman, and Stephen Stills—showed there are a thousand shades between the guitar’s volume knob being set wide open to off. A proper Fuzz Face circuit does some of the best clean tones I’ve ever heard. I discovered this early on in my playing, and it shaped what I go for when trying to build a great fuzz.

Roger Mayer: Considering the worldwide success of Keith Richards’ riff on “Satisfaction,” it would be a Gibson Maestro Fuzz-Tone. As far as a visual icon, however, it would be the flying saucer-shaped Fuzz Face.

Alan Otto: The fuzz pedal that started it all was the Maestro Fuzz- Tone. However, one of the most popular fuzz pedals ever made is the Electro-Harmonix Big Muff Pi, which was introduced in 1969. An early version was purchased by Jimi Hendrix, and the Big Muff Pi was also used by David Gilmour and Carlos Santana. Other users of the Big Muff Pi in the ’70s were Thin Lizzy, Kiss, and Ronnie Montrose. The Big Muff Pi became an integral part of the sound of many alternative rock bands through the 1980s and 1990s, being used extensively by Smashing Pumpkins, Dinosaur Jr., and Mudhoney. Jack White, Lee Ranaldo, and Thurston Moore have also made the Big Muff Pi a major part of their signature sound.

James Santiago: The original 1966 Arbiter England Fuzz Face. Those first units with NKT275 transistors can sound so thick for lead, while still giving you a punchy dirty rhythm sound, all by just moving your guitar’s volume control. Any of the tracks Hendrix cut in ’67, like “Foxy Lady” and “Spanish Castle Magic,” are great examples of this. Hendrix’ really took what could have been a gimmicky effect and turned it into a sound you could base a career on.

Zachary Vex: By definition, an icon is something visual, so the first fuzz that I’d expect most players to think of is the round, smiling Fuzz Face. But if you mean an audio icon, some sound that symbolizes fuzz in general, so many possibilities come to mind that I’m not sure where to start. Is it Keith Richards’ Maestro Fuzz-Tone on “Satisfaction”? Or is it the Mosrite Fuzzrite that was allegedly built into Norman Greenbaum’s Telecaster used for the amazing texture on “Spirit in the Sky”? I say “allegedly” because I’ve conversed with Norman at length about this, and he really has no idea what the circuit was. Or is it the smooth, buttery Garnet Herzog tube fuzz used by Randy Bachman on “American Woman”? For me, it will always be the Jordan Bosstone my brothers played through at my cousins’ house in St. Louis Park, Minnesota, when I was in elementary school. I’ll never forget that texture. It’s my personal ultimate iconic fuzz. I suppose we all have one.

Why do germanium and silicon transistors sound different in a fuzz circuit?

Michael Fuller To my ears, germanium transistors always have a rounder edge at the breaking point, while silicon transistors put a cool arc-welding kind of snarl on the notes.

Roger Mayer The electrical configuration used in germanium circuits usually is different from that of silicon designs, so you can’t make a comparison simply by swapping out parts from germanium to silicon. When a full circuit analysis is performed, here are the main factors that differentiate the two types of transistors: The diode-junction voltage parameters as the device begins to conduct are smoother for a germanium transistor, which means the transistor goes into distortion more musically. The overall current gain of germanium transistors is less than silicon, and also not as linear. In musical terms, this means the circuit changes as the level changes, so the circuit becomes more player friendly in terms of dynamic feel. Germanium transistors have less gain at high frequencies, and their performance is also greatly affected by temperature, which impacts stability. Germanium fuzz circuits generally have lower input impedance and tend to load down the pickups more, which makes them more sensitive to changes in guitar volume.

Allan Otto Silicon transistors typically have more gain and a higher frequency response than germanium transistors. This makes a silicon transistor-based fuzz circuit sound brighter and more compressed. Germanium-based fuzz circuits tend to roll off the high frequencies, which makes them sound warmer. The lower gain of germanium transistors also causes these circuits to be more touch sensitive.

James Santiago: As a player, I’ve come to appreciate the two simple differences I hear in circuits like the Fuzz Face, which are treble response and overall gain. While it’s not always the case, germanium tends to be a little warmer and more squishy, while silicon yields a more crisp top-end and higher gain. That said, I’d have to say that a good silicon transistor fuzz can still give you some amazingly warm tones just by finding the sweet spot on the fuzz gain knob. If you play quarter notes on the open A-string while slowly dialing the fuzz knob back on a silicon Fuzz Face, you’ll eventually cross a threshold where the high end comes down, and you get a smoother tone like a germanium fuzz. There’s a ton of usable tones just in that quarter-inch range of the knob. I used to be guilty in the past of just cranking up the fuzz or overdrive knob and judging a pedal on that tone. I broke that habit 25 years ago and I’m glad I did. I would have missed out on some amazing sounding pedals.

Zachary Vex The simple answer is that silicon and germanium are different materials, but I’ve never met anyone who could actually explain why they sound different. I can tell you that the fuzz texture coming from some germanium transistors I’ve used in the earliest Fuzz Factory pedals is very velvety, and, in general, I find silicon transistors to be harder or harsher sounding. It might be possible that the waveforms at the leading and trailing edges of the square waves have slightly different shapes—perhaps more rounded in germanium fuzzes. But from an engineering standpoint, not a lot of information has been published about the way audio transistors perform when they’re clipping. Most engineers didn’t care to study transistors outside their linear operating zone, which was what most audio circuits were designed around back in the day.

What factors determine why some fuzzes are more dynamic and touch sensitive than others?

Michael Fuller Input impedance, simplicity of the design—meaning fewer gain stages—and most importantly, the transistor type and gain choices. These factors have the most affect on dynamics in my experience.

Roger Mayer It is very easy to design an electronic circuit that makes a non-musical form of distortion and doesn’t respond well to player input. These circuits usually have massive amounts of electronic feedback, which results in a sound almost unaffected by what you are playing. Most players I deal with want a pedal that responds dynamically to their touch, while retaining the instrument’s tonal qualities. This is the principle behind “feed forward,” which involves using the input signal in various ways to modify the operation of the circuit to produce the desired sound and dynamics. Since this information is derived from the player, the circuit will feel more touch sensitive. A good circuit design will use feed-forward techniques to control parameters such as recovery time, equalization, dynamic distortion, and gating effects. It is by far the most creative technique too, as the possibilities are limitless.

Alan Otto Careful attention to the gain structure of a fuzz pedal will yield more dynamics and touch sensitivity. If the fuzz pedal has too much gain, the sound will be more compressed and less dynamic.

James Santiago: Nothing destroys the sound and dynamics of a great fuzz pedal like badly placed buffers and impedance mismatches. Many vintage fuzz circuits were designed to be driven by low output, highimpedance guitar pickups. As soon as you add a buffer between your guitar and fuzz—meaning pedals with silent, non-true-bypass switching— you’ve changed the impedance of your signal. Even when those effects are off, your fuzz still sees an active circuit, and your juicy tone will turn to hissy, compressed icicles. If at all possible, it’s best to place your buffered effects after the fuzz. Even then, you still may notice a little scooped midrange and added top end, but at least the sound is usable. Another solution is to use true-bypass loop switchers so you can completely remove those buffers from the chain when your non-true-bypass effects aren’t being used.

Zachary Vex: I think circuit simplicity is really the key to maintaining dynamics. One- and two-transistor fuzzes have lower gain than more complex ones, and that means less clipping as the wave amplitude dies off. Another thing that can make a fuzz more touch-sensitive is proper biasing, which makes the waveform more or less symmetrical and causes the output to sound more or less clean at lower input levels. I once played through a one-knob Fuzz Box by Colorsound, and Dick Denny had somehow biased the thing so it sounded so perfect as it decayed that I was completely astounded. As the fuzzy note died off, it suddenly went perfectly clean at the very end of the sustain, transitioning so smoothly from being fuzzy to silky-smooth clean that it seemed like magic. I didn’t have the money to buy the pedal at the time, so it was sold to someone else. Eventually I ordered one and was saddened to discover that mine sounded quite ordinary. It must have been just that one with the perfect decay. I wonder to this day if the pedal’s owner has ever realized what he has.

In what ways have modern players helped to evolve the sound of fuzz?

Michael Fuller I’m still listening to vinyl, so I don’t get to identify a lot of modern players or evolution that you speak of. I do like what Dan Auerbach of the Black Keys is doing, and I think he used our SoulBender and Tube Tape Echo on their last album. Doyle Bramhall II sure knows how to use a fuzz, and I hear fuzz sneaking back into music here and there—like in clothing stores and malls where they subscribe to some sort of satellite or cable music channels. I couldn’t tell you who most of these artists are, but hearing a fuzz in the context of this kind of pop music brings a smile to my face.

Roger Mayer The advent of tapping and shredding led me to design a circuit that responds very well in terms of sustain and tone, but also doesn’t introduce any nasty artifacts or noise between the notes. The absolute recovery and cleanliness between notes is very important, otherwise the player’s high-speed technique results in a blurring of the notes.

Alan Otto Certain styles such as heavy metal require a more in-your-face, harder type of fuzz sound. This has led to the development of fuzz pedals that are more compressed, with a brighter sound that cuts through the mix better. A variable midrange control has also become a key feature of these kinds of fuzzes.

James Santiago: There are lots of great young players that have taken the fuzz sound out of its classic rock ’60s and ’70s roots. Since our company also makes products that supply power and do true-bypass loop switching, we see pedalboards and racks every day. It’s great to see that nearly every rig has some type of transistor fuzz on it. For a long time, if you were a Hendrix guy, you had just a fuzz. For blues it was the Tube Screamer, for modern rock it was a Boss DS-1, and so on. Now we see players that want to create with all those colors and more in the same rig.

Zachary Vex I don’t know if it’s the players who have evolved the sound of fuzz. I think designers have been evolving the sound and the players pick up on the new fuzzes and adopt the sounds. Matt Bellamy certainly came up with a trademark way of putting my Fuzz Factory to good use on his first few albums, and having it mounted inside his guitars gave him the ability to adjust the knobs on the fly, which was definitely something new. Jack White’s use of the Woolly Mammoth on the intro to his James Bond theme song [“Another Way to Die” from the film Quantum of Solice] really hearkened back to the ’60s for me, which isn’t so much of an evolution as a kind of rediscovery of a lost tone. Dan Auerbach of the Black Keys has done that with a multitude of new fuzzes as well, including the Z.Vex Mastotron and Earth- Quaker Devices Hoof Fuzz.

What are some of the challenges in designing the next generation of fuzz pedals?

Michael Fuller: I had to discontinue most of my fuzzes a couple of years ago because the transistors that used to cost me 25 cents apiece in 1993 started costing over seven dollars each! And when you add that to all the other parts and a $15 enclosure—plus wages, taxes, rent, utilities, and workman’s comp insurance—it became impossible to do on a larger scale. I recently approached the manufacturer that made my favorite germanium transistors from 1993 to 1997, and struck a deal to buy tons of them, which got the price down a little and allowed me to resurrect my 69 and SoulBender. In bringing back my classic fuzz lineup–the ’69mkII, ’70-BC108C, OctaFuzz OF-2, and SoulBender SB—I redesigned them into smaller enclosures, and I filter the DC better in the power supply section for better sustain, or at least less atonal static-interruption of the notes. I also got rid of the loud true-bypass thump that happens when turning the pedal on and off by using a transistor in a new way to slowly ramp up the LED—eliminating the sudden powerspike that causes that noise. Fuzzes put me on the map back in 1995 when Guitar Player did a cool write up on my pedals and things took off in a big way. Here we are 16 years later, with 18 employees and 20 products or so. What a wild ride it has been!

Roger Mayer The advent of modern recording techniques and small studios with limited soundproofing has made the challenge of obtaining good recordings interesting. I am now offering Dual Band pedals that incorporate a studio approach to obtaining your tone at lower volume levels, while still having a very powerful effect. The popularity of mp3-type devices for listening to music cannot be ignored either, as the frequency response of this type of system creates a difficult task for the mixing engineer and for someone designing effects that will cut through the modern styles of music that are often listened to on these devices.

Alan Otto With the evolution of sound modeling and digital circuits, fuzz pedal designers will have a large palette of sound possibilities to work with. It is possible to design a digital fuzz pedal that emulates the sound of many different types of fuzz. Electro- Harmonix, however, feels that discrete circuits have much better tone than modeled fuzz sounds.

James Santiago: Consistency has always been an issue with these types of circuits. Because they are so simple and elegant in design, if any one part is slightly out of tolerance, you’ll get a huge variance in tone from one pedal to the next. Also, as we move forward into more pedals and rack processors being DSP-based, it’s going to become more challenging for players to fit these fuzz dinosaurs into their “smart car” world.

Zachary Vex Designers have to come up with new, original circuit ideas to get more interesting textures. They’re out there. I’ve got an interesting idea I’ve been toying with since last night, and I’d love to tell you about it, but I’d have to lock you in the basement until I release the pedal. There are definitely more design approaches that can be taken. It’s only a matter of imagination, really. Something about the human ear really loves fuzz. As a designer you always know when you’ve got a good one, because there’s that little tickle that makes you smile when you hear it. Challenges? Perhaps one is using modeling technology to come up with new ways of playing with waveforms that haven’t yet been heard. Not models of things that already exist, but new sounds that can’t be or haven’t been made with individual circuit components. I think the purest fuzz tones will always come from discrete components, however, and as long as they’re available, designers will keep screwing around with ways to hook them up wrong to get the right sound.

Germanium 101

Dunlop Manufacturing’s Senior Engineer Bob Cedro and Director of Electronics Sam McRae teamed up to give us this rundown on what makes a fuzz tick, and why germanium and silicon transistors bring different aspects to the tonal equation.

A classic fuzz circuit basically involves a guitar signal driving transistors to their maximum (saturation) and minimum (cutoff) conduction points. This action transforms smooth guitar signal waves into squared-off, fast rising and falling pulses. The specific shape of these pulses determines the tonal character and responsiveness of the fuzz, and a transistor’s unique characteristics will determine the overall shape of these pulses. Germanium transistors usually have a slower signal reaction time (which acts like a built-in high-frequency rolloff) and softer saturation characteristics when compared to silicon transistors. These differences make germanium transistors sound warmer and smoother than silicon transistors.

Because germanium transistors normally have four-to-ten times less signal gain than silicon transistors, they tend to clean up better at reduced guitar volume settings, although, high-gain silicon transistors can be better at sustaining notes or chords. Also, a germanium transistor doesn’t saturate as well as a silicon type. This means that a saturated silicon device will produce approximately 30 to 40 percent more output signal than a germanium device.

Lastly, changes in temperature greatly affect the performance of germanium devices. Rising temperatures drastically increase leakage current, reduce signal gain, and shift the critical DC operating point of a germanium transistor. Therefore, a change in temperature changes fuzz tone and character, and, in extreme heat, can even cause the germanium transistor to stop working. This poor temperature stability was one of the reasons why silicon transistors became the preferred solid-state device for designers. But in the fuzz world, limited transistor performance and germanium pitfalls may be the very ingredients that achieve the Holy Grail of fuzz tone.

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