The Dirty Truth
By Daniel Brooks
Whether you like it sweet and sassy, hot and hairy or warm and fuzzy, chances are you’re using some kind of gain effect to push your sound into that sweet spot. As common and interchangeable as they seem to be, overdrive, distortion and fuzz are not necessarily the same thing, despite the blurry distinctions between them. To truly understand the difference between overdrive, distortion and fuzz, it is necessary to understand how each effect works with your guitar and your amp.
As you probably know, a guitar pickup works by inductance, the phenomenon of physics in which a change in a magnetic field creates changes in current in a conductor, and vice versa. It is the actual physical phenomenon by which we transmit and receive radio, television, radar, satellite communications, and wifi, to name a few. In our guitar’s pickups, a coil of fine copper wire is wound carefully around a magnet and placed so that the guitar’s metal strings pass through its magnetic field. Whenever any of these elements changes position, the magnetic field changes, instantaneously inducing a small voltage in the copper wire. Each time a string vibrates back and forth, it creates an alternating current whose frequency and amplitude correspond directly to that string’s frequency and mass. The signal will resemble a sine wave that has been reshaped by the complex array of frequencies from all of the vibrating strings, as well as the natural acoustic properties of the guitar’s wood, hardware and electronics to reinforce some frequencies and dampen some others, creating a tone and timbre that is unique to each guitar.
The guitar’s signal is input directly into the first preamp stage in your amp. In any tube, like the ones in your preamp, a white hot emitter radiates electrons into the vacuum where they are absorbed by the negatively charged anode, creating a substantial current. Between the emitter and the anode is a control grid, whose variable electrical charge allows more or less conductivity, allowing more or less current to flow through the tube. When a guitar signal is channeled through the control grid to serve as the variable electrical charge, the output of the tube will recreate the frequencies and amplitudes of the guitar signal, modeled in the actual, much larger current of the tube. This is the amplified signal that is sent to the next preamp stage or to the power amp and then to the speakers. Every tube has a maximum and a minimum amount of current it can conduct. If the peaks and valleys of the guitar’s signal require the tube to exceed its maximum or its minimum, the tube will flatten out at its limit, effectively clipping off the top and/or bottom of its amplified signal. This is the naturally overdriven signal we all love.
At a high enough volume, any tube-driven guitar amp will deliver that overdriven sound. When you crank up your amp to get that sound, the high enough volume is often far too high for the enjoyment and well-being of your audience, since both your preamp and power amp are processing a lot more voltage. An overdrive pedal will work with your tube amp by boosting your guitar signal beyond the limits the preamp is designed to process. It will clip the signal naturally, regardless of the level at which your power amp is working, and let you bring that sweet spot down to a much more audience-friendly volume level. Overdrive effects are typically little more than a boost or a preamp with some mild clipping circuits. Most have some self-generated distortion, especially at higher gain levels, but they tend to preserve, or even enhance the natural tone of the guitar and amp. Unfortunately, overdrive pedals often lose their sonic charm when played through a solid state amp. Fortunately, there is an alternative.
Distortion pedals simulate the clipped signal of an overdriven tube amp. They can work with solid state or tube amps, and the boost they offer can create some interesting sounds when used to push a tube preamp into overdrive, but they are designed to create a sound-in-a-box rather than a naturally enhanced tube sound. Because it is, essentially, a waveform-altering circuit, relatively free from the inherent design constraints imposed by the performance limits of a tube, there is a much broader range of “distortion” sounds available on the market, and they tend to create a much heavier sound, from a hard-clipped, raspy buzz to the high-gain, sonic apocalypse that is the signature sound of heavy metal.
Fuzz pedals were the original dirt boxes, one of the first effects of any kind (along with reverb and vibrato, of course). They were originally designed in the early 1960s to lend texture to an amplified guitar tone, like the reedy rasp of a saxophone. The earliest designs worked maybe a little too well, the excessive clipping of germanium diodes creating a warm, enveloping sound that practically obscured the guitar’s natural tone beyond recognition (Later designs used more reliable, more efficient silicon diodes for their clipping circuits to create a brighter, edgier fuzz effect). Guitarists loved it, of course, since it remained responsive to the feel and dynamics of the player and opened up what many saw as a whole new world of creative possibilities. It was, perhaps, not the sole inspiration for some of the most memorable music yet recorded, but it is difficult to imagine “Satisfaction,” “Purple Haze,” or pretty much any classic 1960s psychedelia without a generous coat of fuzz.
A word about pedal placement is in order (get it?). You are, of course, free to use your overdrive, distortion and fuzz pedals any way you like, but, you’ll probably find they sound better when placed as close to the beginning of your signal chain as possible, the output of the effect(s) going into the input of the amp. You’ll want to place lower gain pedals before those with higher gain, overdrive into distortion into fuzz. And while there is always room for experimentation when it comes to the relationship between overdrive and wah pedals, most people prefer placing their wah pedal before their fuzz pedal for the best effect. What do you think?